Forwards Matls Used in Long-Term Seismic Program Meetings in San Francisco,CA During Apr & May 1990

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REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS) ACCESSION NBR:9007250057 DOC.DATE: 90/07/17 NOTARIZED: NO DOCKET FACIL:50-275 Diablo Canyon Nuclear Power Plant, Unit 1, Pacific Ga 05000275 50-323 Diablo Canyon Nuclear Power Plant, Unit 2, Pacific Ga 05000323 AUTH.NAME AUTHOR AFFILIATION SHIFFER,J.D. Pacific Gas 6 Electric Co. RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk) SUBJECT: Forwards matls used in long term seismic program meetings in San Francisco,CA during Apr & May 1990. DISTRIBUTION CODE: AOOID COPIES RECEIVED:LTR J ENCL SIZE: TITLE: OR Submittal: General Distribution l NOTES:P~W5' / RECIPIENT COPIES RECIPIENT COPIES A ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA g PD5 PD 1 1 D ROOD,H D INTERNAL: ACRS tu NRR/DET/ECMB 9H 1 1 ( NRR/DOEA/OTSB11 NRR/DST 8E2 1 1 S NRR/DST/SELB 8D 1 1 NRR/DST/SICB 7E 1 1 NRR/DST/SRXB 8E 1 1 NUDOCS-ABSTRACT l. 1 OC/~FMB 1 0 OGC/HDS2 1 0 EG F E 01 1 1 RES/DSIR/EIB 1 1

EXTERNAL: LPDR 1 1 NRC PDR 1 1 NSIC 1 1

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f U ~ g E Paciftc Gas and Electric Company 77 Beate Street James D. Shiffer San Francisco, CA 94106 Senior Vice President and 415/973-4684 General Manager TWX 910-372-6587 Nuclear Power Generation

July 17, 1990

PGKE Letter No. DCL-90-185 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Hashington, D.C. 20555

Re: Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Long Term Seismic Program Meetings Gentlemen:

As requested by the NRC Staff, PG&E is providing a copy of the presentation materials used in the Long Term Seismic Program meetings in San Francisco, California during April and May 1990.

Enclosure 1 — Seismic Source Characterization Meeting, April 17-20, 1990.

Enclosure 2 — Earthquake Ground Motion Meeting, April 30 — May 1, 1990. Kindly acknowledge receipt of this material on the enclosed copy of this letter and return it in the enclosed addressed envelope. ncerely,

. D. Shif

cc w/enc.: H. Rood

cc w/o enc: A. P. Hodgdon J. B. Martin P. P. Narbut S. A. Richards CPUC Diablo Distribution Enclosure

3220S/0084K/DNO/1587

90072500;7, 9007t7 O 5/I PDR ADOCK 05000275 P PDC Pgd/ l I c" PGhE Letter No. DCL-90-185

ENCLOSURE 1

VIEHGRAPHS FROM SEISMIC SOURCE CHARACTERIZATION HEETING LONG TERM SEISHIC PROGRAM

SAN FRANCISCO, CA APRIL 17-20, 1990

90072500g7 3220S/0084K h

I NRC/PGKE MEETING ON SEISMIC SOURCE CHARACTERIZATION DIABLO CANYON LONG TERM SEISMIC PROGRAM ONE CALIFORNIA STREET, ROOM 271 SAN FRANCISCO, CALIFORNIA APRIL 17 - 20 1990 1

AGENDA

TUESDAY APRIL 17 '990

8:30 a.m. Introduction

8:45 a.m. Hosgri Fault Zone -- Style of Faulting

guestions GSG 1, 2, 3, 4, 12, 13

guestions SSC 2, 4

12:00 noon Lunch

1:00 p.m. Hosgri Fault Zone -- Style of Faulting (Continued)

4:00 p.m. Lorna Prieta Earthquake Issues

Field Trip Discussion -- USGS (Dave Schwartz) 5:00 p.m. Adjourn

WEDNESDAY APRIL 18 1990

7:00 a.m. Field Trip: Lorna Prieta Earthquake, Santa Cruz 7:00 p.m. Adjourn

LSC/WUS:sjm - 4/9/90 FILE: NRCAPR90.SSC

The southerly part of the San Simeon fault trace extends southeast from a saddle south of the area where Arroyo de la Cruz turns inland into the mountain front. This part of the trace follows the base of the prominent east-facing escarpment forming the west side of the valley of Arroyo Laguna and then crosses a marine terrace lowland fringing San Simeon Bay. In addition to field mapping by ESA (19?4), and Hall (1976), this part of the fault was investigated by Envicom, (1977) Qater reported on by Asquith, 1978), which used ground magnetometer traverses to identify fault strands and backhoe trenches to expose them. This part of the fault zone consists of a pair of strands separated by a down-faulted slice which underlies the floor of Arroyo Laguna Valley and extends to the head of San Simeon Bay. Two of the Envicom trenches (trenches' 5 and 6) exposed a waw Q west&ipping reverse fault along the trend of the west slope of Arroyo Laguna. In both trenches Franciscan melange bedrock was faulted eastward against and over a. folded se uence of sand silt and gravel interpreted by Enyicom as old marine h of San Simeon Bay. There, contacts between rock units are concealed by older dune sand deposits, but the units exposed along the shoreline are, from west to east, Monterey Formation, marine fossiliferous pebbly sandstone (in a single I

, ~>Jc

J. SAN SIMEON FAULT

Airport Creek Trench 0

N66E Zone of Fractured Peds

Topsoil (A) (A) Qt O g+E (E~) ~ 2 X SlltY ClaY (Bt) ~ (Bt~ Q3 I ) I I Q3 I I i ~'- Sandy C)ay Y, QS Sandy Silty Clay Jl +I I Ab (Btb) Z QS Silty Clay ~ . ij Buried A mb) O Silty Clay Sandy Clay (Bds) 06

Buried A (Ab)

Fault Gouge 9 Silty Clay

' N40W Sack Clay <'0 Slickensides plunge 6-7'E

s s ~ ~ ~ ~ ~ a ~ I 1 Sandy Clay 4 C-14 AGE 10670 %260 B.P.

X = Modern Soil 0 2 FEET Y, Z = Buried Paleosols

SW TRENCH T-4

SAN SIMEON FAULT ~ Airport Creek (MAJOR TRACE)

TRENCH NE T-3 TRENCH 8,950 s260 T-1 SW ~ SW ~~ ~ nys t NE 1 ...... " ~ „.s'~ i t " EXPLANATION ~l-.~r o' . t a" S a S,;",. ".:. 1%" 9,760+180 QUATERNARYUNITS 0 S r r Q Topsoil (A, AB and E horizons) Main shear N40W, Af~ 10.690 <130 grooves plunge (Holocene) 6. g SF 11,150 at15 irSr'.>.". Younger Alluvium (Holocene) sw TRENCH Older Alluvium (late Pleistocene) Ig T-5 NE SHEAR ZONE UNITS

I'ain Deformed Older Alluvium (Tertiary?) shear Afy N4'IW, mullions ~ > p Fault gouge plunge9- tte SE 10.670 '260 D MESOZOIC UNITS

t Franciscan Assemblage and related rr a rocks (Jurassic and Cretaceous) l 13,790 e260 TRENCH T-2 NE

Fault; dashed where approximate; A away, T towards Main shear N25 ~ 40W, 0'ooves plunge Contact; dashed where approximate 35160 0560 Radiocarbon age in years B.P.

Figure 8. Simplified logs of Airport Creek trenches showing a major strand of the San Simeon fault (View to NW). I f Q

S',I GEOLOGIC LOG OF THE SAN SIMEOA FAULT EXPOSED IN AIRPORT GREEK TRENCH T-1

lf0$ 0 -M VltWkIT SI1 0010 Or10 OI00 OI40 OI$0 Or$0 0.10 OI$0

$K dINOId Iorlllog Ol rhlKIt«0

20rN 01 ««hah f orohge hearts vrNN Ito of sar«NI . ad«Id flrNera dared cloy IIIrhgI«NI S«N sehdg llhl, oracy IvNvNI eoKK ethd grKIKNOIICtrlIKN co«IKI INcorNO Ihrgldhcl 14 «Nh 0vel. Crsadehll lNIIof IOCO, rdddyeohto Aooro SOON Kael Closer echo. Ahodsr «rovhdtd ~IOIKsdoh INcvrKahd madel cger soSN oh INds. Klhestd dhe Ktrd ArcvtK lrKorhN rrNrlt cshls.l or ION Srh40gl dedeeedeh INCVra sl dre trey ~4y: sharded vrfeca adeN hht fgaly Kggcvrv ~tlgs KNKafoot,'ahCaro I ggrdd lier. CatK caerde 10 aei: dred llhrcvrKIII aec«he< aarcrde ICC 0 ho«had red. «a ol IMNsl rey chere OPSOS1$ ~ 011 0 OOOONI 04 Kthwty Srh. COKI 011 0, gNOCCK 0

I [TQFi Tres 'Ih 1 A

I ~ ~ I

~ / "r p Q ~ -0. 0 Ml Inl 0 0 Ne red c rani ««44th llroh asldr. llhahKI4 ffhtdrdrhd ~ r ~thdKI ~ kaohthd Io ' I Ssht arorerfr slhssv ~NOONre4, Origo dr ad«Id ~horVl sehsahrrN. OOKO. aorvdhd CrdK heed« KOIONON,red shell MOOWrhha rrvrhrh 4lrhe4 Ilorh9 lll ScohtN4 Vah Orrd ~ Aaarasi«ONKO rv rated«N ehd hKKr los vre, sf Co«VCIKSIW seer«ed I«N ortrer Mor «0 ca«cthvte4rN 04 osl4ked INshK loca Otds rh vvevhgt4 IINrlOhd TIAO Kre« Othsls 14C 10 ~orNON coorso ore«N4 wd vied OKor«oteod Icawo ~OWSIN tlNN dldffl$ «NINO II.fSO gII0 er ~ S. Cared cfog Kehr vvy Ivrohdhed seed«shel yr OA Shod KSSW COOSKI IlKvNO. IOKIKvtvhg Co«roasrN chohool wroV roK TshrrcdKor«00N4 cfeley Is«4:afvlgrlleyl I I dhrKON tgd«K gorge $0«gr sill.OllorrhH. ffrN dr deed. hlehly ollldcl C 1. 10l$00ISOyrht. aldd y OINerto Arh:em: gsa dohd vorsorea

sheer; Klow,eho 0 cora cohrKII (g Oodof ChrdNdraa r40lltavhdlhl dsrdel«N grthor Oar Ireo.w. Odrt arsy aohdfhg cohvolad ar l4c sr ~ hc ~ 44«tl rrrreri afsdr ~feeds;rtrr Iddlrhtvll ar««K $ - I'401:retel ~ I Oat«el helhrld lao fred«e«O. Os«4; ~ roeear I ~ lrrvhehdrlhdr vhrvssrrho Vds4sh IOVIVltIs sfell dNK IarN vrlKIMgl1 1 arrest«girl shd a ~rholnvds oerdrl

N15 E

0 ~ 60'0' '+ 10'0'0'0'0SOIL: brn. to dk. brn. " r. pebb. with scatt. boulders TERRACE SAND: tan, fr. gr.

~ Sl TERRACE GRAVEL: Can to buff to rd-brn., ang. to md. pebb. and cobb. clayey sand natrix ~ 1h in

~ BEDROCK: shale (nelange) weathered 10 to nassive clay, blue-gy. to buff with sone shale nasses.

/::. ~ . ~~:.. - . ~ , I ~ ~....r.% .'-..% i. '. cs TREIICH 5 q ~ Faulted 10'S'0'49E

15'ault "w+u ~ N40E, 80N TERRACE SANDS, SILTS, AND GRAVELS; in anticlinal fold with dips up to 35 deg. ~,+,4 b

v ~ r . i ~ r v r 10'0'0'0'0r ~ ~ ~ ~ g ~ 0 r ~ ~ 0 / 0 o o ' / r ~ e '5''0'LD ~ 4 0 O r o ~ ' ~ ~ ~ s 5 r

BEDROCK: shale as above ALLIIVIW:silty clay. brn. to brn-tan, occ. pebb., and 10'igurc O N35N, i~O ~ clayey silt snd silty sand, 12 90~ pebbly. tan bec. brn. at TRENCH 6 top; cobb. and 18" boulder GEOLOGIC LOGS TERRACE: as above east cnd trench. at of TRE!ICHES 5 a 6 f II

, ~

l MAP OF TRENCH LOCATIONS AT AIRPORT CREEK LOCALITY SAN SIMEON FAULTZONE

Spring

Env. 4 Deflected Channel

T-3

Major strand of San Simeon fault T-5 T-2

Env, 6

Env. 5 j'~.7

~ ~ X 76.7

Airport Creek

Trough of probable p Ep tectonic origin

~ ~ ~ ~ ~ ~ ~ ~ 0 ~ ~ 'o ~ ~ ~ ~

50 in

30"-wide backhoe trench

Env. 1 Backhoe trench excavated by Envicom

EP-1 O 30"-wide backhoe exploratory pit 'I C

jl,

<1 U g

~ I/

4 QUESTION GSG 1

?he logic tree used to characterize the Hosgrl fault zone seems to capture the suite ofdi+crcnccs of opinion about the style offaulting. ?herc arc, however, opinions other than PGckE's wkly mpwt lo thc weighting ofthc varktus paratnctcrs.'n ccnain areas along the fault zone thc intcrprctations based on the geological information and the interpretations based on some geophysical (seismic reflectio) interpretations appear to dier. 1hz dip ofthe Hosgrl ls a case lipolttt. PGkE s interpretation ofits geophysical data is that is shows the Hosgri as a mainly stccply dippingfault. ?his along with the geologic information is interpreted as being indicative ofpredominant strike slipfaulting. J. Crouch presented seismic riflection data which he interprets as showing thc Hosgri to bc a low angle thrust. Ham you looked at this information? 8%at is your intetpretation? Do you agree with Crouch's dipping fault? How do you rcconct'ic this with the hypothesis ofstrike slipfaulting7 Could thc differences in the geophysical data bc duc'o thc'ata processing methods? Also, many ofPGcfcE's interpretations of senical faults appear to bc based on shallow high resolution data and there may not bc strong evidence to cstcnd than in depth as vertical. Provttle yoiirbasis Jbr tktcnttliilng the dowa dip gcotnctty and the djgbcnccs'ith those tncntloncd above,

APPROACH

~ Evaluate data and interpretations of others

Crouch, Bachman, Shay

McCulloch, Lewis

perform structural analyses

~ Provide basis for PGBcE interpretation

prepare series of montages to illustrate interpretation of geophysical data

describe data base, data processing, velocity model

describe interpretation procedures, constraints, limitations

incorporate results of structural analyses

~ Compare PG8tE interpretations with interpretations of others 0

r g< Cr,g "g. "ye

' I, ~

y" Fault-Bend Fold PURISIMA HOSGRI STRUCTURE FAULTZONE

Axial Surfaces " vu QrI 'cu

I r

\ rc~ ur 'l ~. 8'".l."

Cll tu ICu IV Ll I O CL ~r u 4I t uCr ' 41 2.0 lu4 l

~ ruI'lluu 'luc ul,, r ~« u V' rr I~~uuuv 'uu r I ~,u I 'r

,'"," West-Tilted cw'L Domain I~ PGSE-3 „„, East-Tilted, ':~000 3 0 Domain

(T - T'n Point Sal Reach Montage)

Fault-Propagation Fold

SttOTPONTS 1500 1 150 t250 1255 1t5I 1 l55 1050 0.0 West-Tilted Domain

1.0

s tt AxialSurfaces CL 2.0

3.0

J106 'I:48,000

(J106 on Piedras Blancas Montage) ~ ' PURISIMA HOSGRI STRUCTURE FAULTZONE Ocean Floor 500 l50

Mid.Pliocene 1.0

Top Miocene 2.4 m Top Basement t I 0 t I I t I \ I I 2.0 ~ I I t I I ~O 4.0 Q

PG&E-3

Symmetrical gently dipping limbs = fault bend fold

SttOtPOItt tl 1SOO 1 l50 1l00 1050 1500 1250 1200 11SO 1100 1050 Ocean Roor

1 CS m a Top Bas men 2

O 0 2 t0 l EO J106

Asymmetric fold with steep short forelimb = fault propagation fold t 'N . PURISIMA HOSGRI STRUCTURE FAULTZONE

acean ROOI 500 450

'5.0 Mid-Pliocene

Top Miocene Basement a Top t l :-:.:.:.:.:::: ::; :; :::::: :: \:::;:.:.. .:: :::t:: .. l g I // 2O 0( O '0m3 :::::::::::::::::::::::::.:::::::::t'::::::::::::;:::::\:::::::::::..:.:.....'. ~ :::.'...'.'.:.:: 'Possible R'ange.::4:::.::: ..'.:.'.:.':.'.:.'.:.':::: . 40 g -':.:.::.:::.::.::::::.::.:::.;:.of:Faults:Positions',,:::::.:::..;::

PG8(E-3

Fault position can be anywhere within broad range

Olpoklta (500 SI50 ((50

5 lV nl Q ciht5 Top Bas men 2

O TL 3 3 Possible Range of (0 Fault 4 J106 Positions

Fault position is tightly constrained I

l'g

~U ~g Fault-Bend Fold PURISIMA HOSGRI STRUCTURE FAULTZONE SHOTPOEH1S

0.0

II 'l I » ~ ,n~ I"II'

~ww» 1.0 I w WEEI' Q~ wT.

~, '< I''" Ell

~» n O aO ~r. ~»

l@%lE 2llllla

.gI» * 2.0 '4'

nl'll +EE IIIWI Ir u, 'IE»». I» l ~T III+I I Possible II. 1 '- Rangeof ~»lI» ~ Positions I »I

PG BEE-3 '4S 000 3.0

(T- T'n Point Sal Reach Montage)

Fault-Propagation Fold

SHOTPOEHTS 1500 1550 1500 1350 1%0 1250 1200 1150 1100 1050

~ » 0.0

n O EL

C'ossible 2.0 Range of Positions

J106 1:48,000

(J106 on Pledras Blancas Montage)

ONan RN) PURtSIMA KOSGRI ONan ~ PURISIMA HOSQRI STRUCTURE FAULTZONE STRUCTURE FAULTZONE

Mid.plocene Mid-Pliocene I Top Mhcene Top Mhcene I I I I Top Basement I 8 8 Top Basement I I 8 8 I I I I I I I I I 1 I I 1 I I I I I ) I I I 4 I ~4 00

PGS E-3

PURISIMA HOSQRI PURISIMA HOSQRI STRUCTURE FAULTZONE STRUCTURE FAULTZONE

Mid.pihcene I I Top Mhcene Top Miocene I I I Top Basement 8 8 Top Basement I 8 8 I I I I I I I I I I I I I I I I I

POCK PQCE-3 l

~ v

IIII

4kt $

!4' P CJ Fault-Bend Fold

t p -sin(~) [sin(2y)-sin 0) cos(y-0) [sin(2y-0)- sin 0)- sin y

Fault-Propagation Fold

sin(y-y+) sin(y+-P) sin(y-P) m0 sin y sin y+ sin y sin(2y~-p) sin y sin 0

yt'etachment

or Lift-OffFolds ~f I GROWTH FAULT-BENDFOLD:

Model:

I ~ ~ ~ M O O Ov ~

Example: PURISIMA HOSGRI STRUCTURE FAULTZONE

Growth Interval

I I VV'I'IV I ~ I 'I'.0

'IVV

ene ' ~i V

Mioc VV»

i i 'VV

2.0 'III gll

To 8 ement 'VI

V I

v\ V II iV

PGSIEv3 1:08,000 >4

I .I v% P - T'n Point Sal Reach Montage) l+ A, < l,' Ocean Floor PURISIMA HOSGRI STRUCTURE FAULTZONE

500 450

Mid.Pliocene 1.0

Miocene Top t ~ I ao m Top Basement t a I t t I t 0.0 > \ 0 \ 3

$.0 I

PGKE-3

6.0

PURISIMA HOSGRI STRUCTURE FAULTZONE

Ocean Flcof 450

Mid.Pliocene 1.0

Top Miocene 0-0 m Top Basement I 0 'I I t I K t I 0.0 K I O 2

CV 4.0 ~ 10

5.0

PGSE-3

Horizontal scale {kilometers) 0 2 3 4 0 0

2000 m CD E 4000 O

2 K 6000 n

8000

10,000 0 0 0 I I 1 t! j j ~ I ) j il ! I 2000 ! 1 I I CO 4000 I CD j E I I ~j 6000 I I I ] 2 n y I 8000

10,000 Line SM-4 {Nekton 233) f~p

Cg~' SW NE Horizontal scale (kilometers)

4 . 3 0 0 0

2000 —— N ~

C g 4000 g 6000 2

8000

10,000

0 0

1 '~. 2000 I 1. ~ 4000 I ~ I 6000 / I 2

8000 /

10,000

Line SM-1 (Nekton 202) ll 1 A4 SW NE Shotpolnta 1100 0

2000 <

4000

-2 ~

10,000 < -3K

W,OOO! I 18,000 ~ t "5

18.000

0 0 'i I I 2000» I 1 >O~l 1 I .Ii II \ I . ii \ II jl 6000 1 I II

'L \ S 8000- \ I 1 I \ 1 1 g 1 i 10.000'2.COO) i I 1 I \ I I / ~ I I 1 ~ I I 1i,000 I i I j 16,000 I

18,000 LINE GSI.100

SW NE Shotpointe 1000 1100 0 I I 0

eooo 2 ~g 8000 a 10,000 3

12,000

14,000

0 0 II iii %J 2000 I I II Li( I 1 I( jl $ I i xl 4000 \ lly ! I I j eooo I j j I I I I I ! I I ii/' I 22 8000 I I I I j I I I 10,000 l l I I 12,000 I I 14,000

LINE GSI-103

/ J g' ~ ~ ~ ~ ~ ) of'ygne~"

Pno~4 Sl nc &we'4ferwik~ (IHistnual ia kata~ Ter 4ty volcan i'c.g ~RIP IJad48 lfplhy b4gt hldtl f) ( QUESTION GSG 1

Zhe logic tree used to characterize thc'osgri fault zone seems to capture the suite'f digcrences of opinion about thc style offaulting. Ihere are, however, opinions other than PGc%E's with respect to the weighting ofthc varfous parameters, In certain areas along the fault zone thc fnterpretatfons based on the geological Information and thc interpretations based on some'eophysical (seismic reflectio) Intetpretatfons appear to dl+n; 1he dip ofthc Hosgrf ls a case in point. PGdcE's fntetpretatfon ofits geophysical data fs that Is shows the Hosgrf as a mainly stccply dippingfauft. 1hfs along with information fs fntetpreted as being Indicative ofpredominant strike sNp faultfng. J. Couchthc'eologic presented seismic reflectio data which hc interprets as showing thc Hosgri to be a low angle thrust. Have you looked at this fnformatfon7 f Do you agree wtth Crouch 's dipping fash p Hnrn do~u rnsnntttnrhts rthh rhs lggtnthrnr's sfsrtrhn slipfnnhtngp ghttgd tbn„ dtfbnrrttn ll~ lht gnnphtlllnd dnnl hn dnn sn drn ign~orrttnmtng Nsthndrg; rtlrn, nrnnp nfPGdrE s interpretations ofverticalfaults appear to be basetf on shanow high resolution data and there tnay not be strong evidence to extend them ln depth as mrtfcaL ~~tfihjjr%e iowa . i6'p geontett$ and the digcrences with those mentioned above.

CONCLUSIONS

~ Interpretation of steeply dipping fault is based on an integrated analysis of variety of geophysical, geological and seismological data sets

CDP seismic refiection data

ratio of lateral to vertical slip

Point Sal seismicity

Point Buchon seismicity

retrodeformable structural analysis

linearity of fault trace

tectonic and kinematic data

San Simeon/Hosgri pull-apart

regional alignment with San Simeon fault zone

worldwide analogs

~ Down-dip geometry is not based on shallow high-resolution seismic data

~ PG8cE's interpretation of CDP and high resolution geophysical data is provided on the montages {January, 1990) and described in Attachment A.

Hosgri is steeply dipping in upper 1 to 3 kilometers I j),~

lk„gg, QUESTION GSG 1

Zhe logic tree used to charrtctetize thc Hosgrifault zone seems to capture thc suite ofdlgnences of opinion about thc'tyle offaulting. 7hae are, tunvevcr, opinions other than PGkE's with respect to thc'eighting ofthc various panrmcters. In certain anm along thc fault zone the interpretations based on thc geologlaxl information and thc interpretations bared on some gcophyricxxl (seismic rrfhctlon) interpretations appear to diane; Zhe dip ofthc Hosgrl is a axse ln point. PGc%E s interpretation ofits geophysical data Lr that Lr shows thc Hosgrl as a mainly steeply dippingfault. This tdong with the geologic lnfornuttlon Lr interpreted ar being indicative ofpredominant strih. sNpfatdtlng. J. Ctxhud'x I Baw yoa huthul ta thh hhhrm attaat What Is your Iototyrsttulouy Do yaa ahtaa lohh 6tthth'ol F Pox'do recotrdk Could tho dgivcnccs in thc geopthysical data be duc'o the data processing methods'ho, many ofPGc%E's interpretations ofverticalfaults appear to be bared on shallow high resotutlotr data and there may not be strong evidence to extend them in depth as vertlcaL Prrrvkleyour basis for dctcrtrrining thc down dip geonretry and the di+crences with those mentioned above.

~ We have evaluated specific data sets and interpretations of Crouch and others (1984) and McCulloch

~ We do not agree with the interpretation that the Hosgri is listric thrust fault near Point Sal

differences in interpretation are not due to data processing

differences probably due to different interpretational procedures, approach and integration of data.

listric refiector vertically separated by high-angle Hosgri fault zone

~ Listric thrust fault interpretations of Crouch and others (1984) and McCulloch are not consistent with observed deformation and seismicity

faults and folds cannot be restored

contrasting orientation of crustal shortening

Point Sal and Point Buchon seismicity

linearity and lateral continuity of fault trace

ratio of lateral to vertical slip

reverals in vertical separation

San Simeon/Hosgri pull-apart basin

absence of geomorphic relief A4

4 \

t jE

5'~

P ~ & O

as o P~ 0/'y c9 e 0 +~ 0 20 km Og Santa Ynez g

~ Diablo Canyon Power Plant

Faults of south-central coastal California E h Sense Of Slip Definitions

A Normal-slip 90

0 0 .Q. 'p4,, Q. CO 0 ~r g

~cd <+ %Q odor/y 'P~ CO j3 +CO

90 Reverse-slip B From Bonila and Buchanon, 1970

Rake angle g, SS/DS Fault Type degrees (colan g) HN (dip 90') HN (dip 60') Strike-slip <30'1.732 )1.732 )2 Reverse Oblique <60'o 304 >0.577 to 1.732 >0.577 to 1.732 )0.67 to 2 Reverse 90'o 60' to 0.577 0 to 0.577 0 to 0.67

g Rake of striae; inclination from the horizontal measured in the plane of the fault

For a 90'dipping fault plane: For a 60 Nipping fault plane vrith rake of 30': SS 1.732 30'ake V ~ vertical separation os v» 'I sin 604 V/DS os»1 0.866 V/1 H/V ~ ~ cotan ) strike-slip (SS)/dip-slip(DS) 1.732/0.866 2

SENSE OF SLIP DEFINITIONS

Strike-slip Oblique Reverse 21 l:2 Horizontal: Vertical '0 QUESTION GSG 2

D.B. Slemmons proposed that the Hosgrl may be experiencing oblique fault neo&a N set~gask'epths and that this ls being partMoncd into strN» slip and dip sNp on the near sarfaea je4a, As stated by George 7hompson, this region may be responding similarly to the San Andreas region with thc horizontal strike slip component ofstrain being accommodated on thc Hosgri systetn and the eompressional component being anommodated on the sub-parallel reverse faults and folds. AeeMt a dhcussiott ofthere tnodeis their. appnrprktteness and any leppllcatlons ofthese ceaatuts N 4c NIP,

APPROACH

~ Develop concept of strain partitioning

observations

regional versus local

coseismic versus independent

Theoretical crustal model

~ Assess implications for seismic hazard evaluation

~ Apply concept to characterization of Hosgri fault zone

EXPLANATION

Historical earthquakes along the San ~o. Andreas fault zone and bordering thrust 1983 faults showing approximate length of buned fault rupture Co slings surface or

198S Kettleman Hills Axis of Quaternary anticline r ~~ Thrust fault, sawteeth on upthrown block

196S Parkflaid srrara-srrp raulh arrows show sansa or slip

SOUTH Bakersfield

Sen Luis 0' 0

CENTRAL 1952 Kem County + 0/.(

Pt. r Pt Conception .. CALIFORNIA

~ ~ ~ 'La 19Tl San Fernando

s, 1987 O C~ Nhlttler

30 mi

Burma

0 99'

99'5'+ C

15'."

O.. O '. Z".

Andaman 10o+ Sea

+10'0+

'' 50 91' Sumatra ~ .

From Harding and others, 1985 e a Unnamed northeast-dipping tQ thnjst fault subparaliel to 0 Frijoles strand Pacific Ocean

Holocene fluvial deposits deformed and faulted against Purlslma Formation ~ '+Q

~ '. 0 go Fault dip vertical Fault dip N37'E PolntAfloNuev .. ~ Eg

First marine terrace displaced about 6 meters. Evidence for recurrent activity during past 3000 feet 200,000 years

1000 meters (Modified from Weber and Lajole, 1979a) I

g'4

IPt

4 g w~,P( - g) wo:t Eaat L:2 LT ''L." 'I: '...l.."'.I."L 1'~"i ; L'.. ll-'Ptl.t..'I..I':...3 t., I ~ ~ ~ A

~ .. ~ ~ 4 . ~ a

~ ' ~ ' . ~ . ' ~ I ~ I' ~:.~~; h ~

' PUOCBlEgNSTOCBlK

g f c.. I l. (I 3I

Hoitzontal acala 2ml 3 km

~~V~ rA ~ ep v, ~ $J ~ e See Figure SSC Q4-4 for location of profile (From Harding and others, 1985)

EXPLANATION

T Displacement toward viewer A Displacement away from viewer F

1p r I, . «.'h IL

P )

Q. l SW 0

1 ~ ~ ~ ~ J

.BRAwcHtvop. 'f E FAULTS 2

Cg r P 6 ~' I-' 'H (g~ ~ f

4 CENTRhL 'T A STRhND

(From Harding and others, 1983)

EXP LANATlON M Mississippian T Displacement toward viewer 0 Ordovician A Displacement away from viewer E 1t EXPLANATION San Simeon Diablo Canyon Power Plant Point Cy~ ~ ~ 0 Fault, dotted where inferred

Axialtrend of anticline or o syncline Piedras Point Blancas Estefo Antiform

P.~ Buchon Point San Luis South Basin Compressional Domain

(P~ Point Sal 0

Point Arguelto

20 mi

30 km 0

~ 'QC C'P~~> p f

Ey gl

L Regional Local h3 to 8km @3 to Bkm

6 km 3 0

Tertiary Region of lee basinal strain partillonIng. moment release Partitioned structures are not 'ocal during earthquakes. separate seismic sources and must be characterized together to assess Basement source zone characteristics at depth. %?w ,gQ~,; Transition zone.

Regional fuIcruotof'otrofn portftfonlno. Portitonod otrucOtooo Region of large Ro ooporslo oolsllllcootwcoo %0) moment release hdepondent oolco zcoo during earthquakes. choroctorfstfcs.

,,'ega~~~, Base of seismogenic zone or change In rheoiogicat property $ SS SSS Ductile S of crust. 'S'S S Deformation SSS $ $ S Oblique strain in lithosphere $ $ $

$ $ $ $ Q't > Is 'i'iO+ $ $ f $ 5

EXPLANATION g Dispiaoement toward viewer Dispiaoemera away tram viewer

0 5ml

0 8 km A yooei +-. Y.

'I~

Projection of San Simeon Fault Zone

EXPLANATION p+ r Fault, relative sense of motion shown, dashed Hosgrl where location not well constraIned, dotted FaultZone where fault does not deform late Pliocene strata

Thrust fault, sawleeth on hangIng waN, dashed where location not well constrained, dotted where fault does not deform late Pliocene strata

Anticlinal and synclinal fold axis, dashed where location not well constraIned, dotted where structure does not deform late Pliocene strata l Regional strain partitioning

Local strain partitioning

SW Purisima structure 0 Sea floor Mkf-Pliocene Unconfotmlt Mid-Pliocene O O+ Top of Miocene Unconformity Miocene Zone of low moment release during earthquakes Basement

. ~iS Transition n 5 A.

Zone of farye

10 10 6 4 2 0 Distance from fault (km)

EXPLANATION 8 Displacement toward viewer

e Displacement away from viewer 'v EXPIANATION

Historical earthquakes along the San ~o Andreas fault z'one and bordering thrust 1983 faults showing approximate length of . Coallnga surface or butted fault rupture

1985 Kettieman Hills Axis of Quaternary anticline ~~ Thrust fault, sawteeth on upthrown block

1968 Parkflaid Srrike.slip fault, arrows show sense or sip itiform Pt. Estero o> ~o '.. SOUTH

eSen Lub outh Basin Obbpo 1857 Farl TeJon Bakers iield ompresslonal ~ ~ +, orna In

0 CENTRAL Purlslma 1952 Kem County 'w Structure ~~o.

~ Pt. Hgueio ~ e ' ~ ~ ~ ~ e ~ ~ Pt. Conceplan .. r CALIFORNIA 1927 ~ ~ e, ~ l Lompoc Earthquake 1971 San Fernando ' /~ oc

0 30 mi

0 50 km +f,

a. A; 0 QUESTION GSG 2

D.B. Skmmons proposed that the Hosgri nuty be eqmfeneing obliqueJttttlt ntotiow u acksaj~e, m~ml ~gp Rii ~Mo~slip~~slip~S ~~r ~'~ stated by George Zhompson, this region may be respond)ng similarly to the San ~m region wish the horizontal strike slip component ofstrain being anommodated on the Hosgri systctn and the eompressional component being anommodated on thc sub-parallel mme faults and fit. ProviCe a discussion ofthese models their appropriateness and any implications ofthese concepts to thc LZZP.

CONCLUSIONS

~ Strain partitioning is a useful concept for evaluating deformation in south-central coastal California

~ Both regional and local strain partitioning appears to be occurring

regional: Piedras Blancas antiform, South Basin Compressional Domain

local: intra-fault zone upward diverging splays

~ Recognition of strain partitioning is important for characterizing fault behavior and seismic hazard

~ We have incorporated the concept of strain partitioning in our assessment of sense of slip and slip rate on the Hosgri fault zone

contribution of Piedras Blancas antiform

\ contribution of Purisima structure

contribution of intra-fault zone deformation t

jPi (J'

P I

i&~

i1'

0P%gq~K P'

* QUESTION GSG 3

PmAdc the new bformatlon presented at the tneetlng on the upDP rates acnes the HaegrfJfaah sear,'ased on relative displacement ofthe basement, top ofMiocene, thc mid-Plloocne discontinuity and the post-Wisconsin Iow stand, including the uncertainties in thc analysis. Also darify the ~~ ~ct regan&g thc'levation ofthe 18 thouiand year, late Shconsin, kni stand. 7his is given as -120 meters, in Table 3 and Pktte 5 ofrhc Response to Question 491, but as -140 and -160 tneters i» thc discussion, at the meeting ofJune 14, ofthe north Estero Bay slope break, Ifthe lower value is correct, provide the published source or other supporting data for this departurefrotn globally established values. Ifevidence supports both the lower value to thc west ofthc s~oee seatp ofthc Hosgri, and thc mapped -120 meter level near rhc Hosgri scarp, discuss thc rate ofverticalfaub slip thereby implied.

APPROACH

~ Compile vertical separation and rate data

Top of basement unconformity

Top of Miocene unconformity

Mid-Pliocene unconformity

~ Include maximum deformation across entire fault zone, not only individual high-angle strands

include coastal uplift rates

include structural relief on Purisima structure and other areas of strain partitioning

~ Evaluate spatial and temporal variation in rates of vertical separation

~ Evaluate use of late Wisconsinan low sea level strandline to assess deformation on Hosgri fault zone ~ $

4~;

ji<

Cj ~

EI Selsm'l 80-100

S.P. 450 S.P.500 SW Typical shor e Slrarrgraphrc Coturnn Sanla Mar ahr ca IIIIIIIIIIIIIII!llllllllllllllll|l'ell P44NN3 Wel P 0406 Nl T.D. T.O. 5755'n~ 4 5755'esisevlry 0 ~ 4, 0 6a Garnrna Ray 'o o Non o: I.t ad II Marino o..." 'l 5 8 5 ) o, o

Foxen and younger Paocene

Upper Slsquoc P>ocene Upper hence no Sisquoc » Ss Lower Slsquoc Lower Slsquoc

de ~ $ 5000 94 »»»»»l ,»» '» JC I ~ IP C 6000

~»» ISO ~ ~ rde '

~ ~ I I ~ ~ Ix.e ra I aa oo

Ir r ",O 8000 r ~ 0 c)

(From Cla rka nd others, In pres s) 1* VERTICALSLIP RATES BASED ON VERTICALSEPARATION OF UNCONFORMITKS ACROSS THE HOSGRI FAULT ZONE

TOTALVERTICALSEPARATION (m) VERTICALSLIP RATE (mm/yr) SEISMIC LINE Post Mid-P Top-B (-17 to 5.3 Top-M Mid-P Coastal Uplift Post Top-M Maximum'2.8 Maximum'ate'5.3 (-17 Ma) Ma) (%)'5.3 Ma) (-2.8 Ma) Post Top-M Ma) Post Mid-P Ma) (mm/yr) (mm/yr) (mm/yr) (mm/yr) (mm/yr)

nrthern Reac CM-51 428 119 - 309 «0 0.08 0.08 0.04 - 0.11 0.11

W-76A «1922 («1335) 642 404 «0 0.12 0.12 0.14 0.14 («69%)

I-113 «2113 s1541 666 s285 «0 0.12 0.12 0.10 0.10 (s72%)

San u's i o eac PGE-I 857 261 s0.23 0.16 s0.31 0.09 0.32

W-14 710 330 s0.23 0.14 s0.37 0.12 0.35

GSI-85 476 - 619 285 - 404 0.20 - 0.22 0.09 - 0.12 0.34 0.10 - 0.14 0.36

GSI-86 690 380 0.20 0.13 0.33 0.14 0.34

GSI-87 880 571 0.20 0.19 0.39 0.20 ~ 0.40 (0.26') preferred value based on elevation of exposed basal Squire Member onshore

I:5'.GSG-Q-3. T-I March 28, 1990 Page I P

~ I'+

gt'

>c,-

%I+ t

~ Qk~ Table GS 1 (continued)

TOTALVERTICAI.SEPARATION (m) VERTICALSLIP RATE (mm/yr) SEISMIC LINE Top-8 («17 to 5.3 Top-M Mid-P Coastal Uplift Post Top-M Maximum'ost Mid-P Maximum'«2.8 17 Ma) Ma) (%)i (5.3 Ma) Rates (5.3 Ma) Post Top-M (2.8 Ma) Post Mid-P Ma) (mm/yr) (mm/yr) (mm/yr) (mm/yr) (mm/yr)

San uie 0 i» CM-119 881 595 «p 0.17 0.17 0.21 0,21

J-126 1095 571 «0 0.20 0.20 0.20 0.20

GSI-97 1048 598 «p 0.20 0.20 0.21 0.21

GSl-1pp Hosgri 1119 «0 0.21 0.21 0.19 0.19

[Hosgri + Purisima] I [1238] [712] «p [0.23] [0 23) [0 25] [0.25)

1976 953 (48%) 1023 «0 0.19 0.19 0.18 0.18

[Hosgri + Purisima] [1834) [1238] [691] «p [0.23] [0.23] [0 25) [0.25]

Point Sal Reach GSI-1 pl Hosgri 1715 «811 (47%) '04 0.14 - 0.17 0.17 0.34 0 0

13'0 357'547] 13'0.19') [Hosgri + Purisima] [1477) [1167] [0.14 - 0.17] [0.22] [0.39] 19<] ~204 Hosgri 857 571 0.14 - 0.17 0.16 0.33 0.20 0.37

GSI-106 Hosgri 428 - 2095 -215s - 1452 643 476 0.14 - 0.17 0.12 0.29 0.17 0.34 ((0 - 69%) [1143] [571] [0.14 - 0.17] [0.22] [0.39] [0.20] [0.37] [Hosgri + Purisima] [2000]

I:hPr-RGSG-Q-3. T-1 March 28, 1990 Page 2 I

+A,

,F ~ 4 Cg Table G -1 (cotttltltlet))

TOTAL VERTICALSEPARATION (m) VERTICALSI.IP RATE (mm/yr) SEISMIC LINE Top-B (-17 to 5.3 Top-M Mid-P Coastal Uplift Post Top-M Maximum'ost Mid-P

Maximum'ate'5.3 (-17 Ma) Ma) (%)'5 3 Ma) (-2.8 Ma) Post Top-M (2.8 Ma) Post Mid-P Ma) (rltN/yr) (tttm/yr) (mm/yr) (mm/yr) (mm/yr)

S utheru eac G~S1-I 2C Hosgri -732" -0.14

lHosgri + Purisima) f756] f1122J f536J f »O. I4] f0.21J f0.3SJ f0.19) f0.33J

GSI-I 15 Hosgri -524' -0. l4

Hnsgri + Purisimal f 1501) fl024) f524) f -O. l4) f0.19] f0.33] f0.19J f0.33)

I I -O. l4

-357'Hnsgri + Purisimal f976] f 1000] f570J f -0.14) f0.19] f0.33J f0.20] f0.34J

GSI-123 Hosgri 1142 786 -0.14 0.15 0.29

Hosgri I + Purisima] f1261] f905] f476] f-0.14] f0.17] f0.31J f0.17] f0.31J

Note@ I - Indeterminate

'Percentage of vertical deformation of the top of basement unconformity that occurred prior to development of the top of Miocene unconformity. zLate Pleistocene uplift rate based on the elevation of the 120,000-year-old marine terrace. Maximum value calculated by adding a maximum coastal uplift rate east of the fault zone to the vertical slip rate based on the elevation of the unconformity west of the fault zone.

4The presence of the unconformity on both sides of the fault zone allows for a direct measurement of the total vertical separation. 5Down on the east

I:tPGFtGSG-Q-3. T-I March 28, 1990 Page 3 k"

k>$ fty EXP LANATlON ~ Diablo Canyon Power Plant = Boundary between reaches of the Hosgri Fault Zone 0~ ~ Estero i Point p8 Purislma structure gg Maximum post-middle Pliocene vertical slip rate (mnvyr) across ~g~ based on direct -- ESterO 0.26 Preferred value 0qa measurement ol vertical separation using y0 onshore exposure of basal Squire member ~Maximum post-middle Pliocene vertical

e<" 0 QO q,eac~ p~ N POint ——Fault; dashed where inferred Bu vis G

00~ t

cd t0% s».gggS q,eac~ >.~o< o (Ph

<06

0'ZG GSK Punsima Point

Scf 9,eaace

10 mi

15 km gk

1' EXPLANATlON

~r 'fh Diablo Canyon Power Plant \ QS i l Boundary between reaches of the Hosgri Fault Point Estero Zone PS Purisima structure Ester 529 Maximum post-top h4ocene (Top-M) vertical slip rate (mmtyr) across Bay ~Qggyjg ~ Maximum post-top h4ocene (Top-M) vertical

et" ~Q,3 0 —Faell; dashed where inferred peac~ gt ~ ~ Axial trend of antidine or syndine Point Buchon ~A QgL ou,

~g.s +5 Q Point San Luis g,6 9 si.s Q 3I ~pl pa~ q,eeac" GSh + C~ G ,2'

O ~Qadi 70 gy-of r g~S 0+$59 ~eacc>

~ q,eacc> ,si'urisima Point =, AS l~ 10 mi

15 km

Profiles of the coastal zone (0 to -200 m) of south central California showing post-late Wlsconsinan sediments and the San Simeon and Hosgri fault zones

0 Af \

n rn

0 F n HOSGRI 0 r A IT u uo

HeettII 00tuII 0 tt SIMEON

Uo 0

EXPLANATION I F. DCPP Post-late Wlsconslnsn sedlrnent 0 U W. Hoeyrl u 0 Fault: U = up, D = down, A = A 'T e v away, T= towards

A T E. HOSGRI >I -100 oou 00 0 5 kilometers Vertical exaggeration - 25X I. t4o. Pttrtaeeee PL

A T

J. Surf I

W. HOSGRI c'y'K~"~ 'P"

ry EXAMPLES OF FAULT-RELATEDVERTICALUPLIFI'ATES AND ASSOCIATED RELIEF ON ADJACENT MOUNTAINBLOCK

Vertical UpliR Observed Relief F ul m nn mm r Transverse Ran es

Pleito 0.4 - 0.7

Sierra Madre 1.2 - 3.0 1,000

II San Cayetano 0.6 - 1.5 1,000

Owens Valle Independence -0.1 2,100

Lon Valle Hilton Creek 1.0 - 2.0 1,150

Mono Valle Lundy Canyon 2.0 - 2.5 1,650

Others Wasatch, Utah 1.0 - 2.0 2,000

Alpine Fault, NZ 2.5 3,000 10.0 - 20.0 3,000 kgb Observed versus expected range front elevations, past 850,000 years

1000

850 m 800

~ ~

600

ELEYATlON J t> (meters) ~ Expected:.- 400 (1 mm/yr) .

247 m 200

Observed, ', {0.24 mm/yr) 0 0

j! PUBLISHED VALUES OF LATE WISCONSINAN LOW SEA LEVELSTAND

-80 meters Badyukov and Kaplan (1979) Pirazzoli (1987)

-90 to -100 meters Milliman and Emery (1970) West Atlantic Cunay (1965) Texas Gulf coast

-120 meters Curray (1965) Gulf of Mexico Nardin and others (1981) Santa Monica shelf, CA Shackleton (1989) Global compilation

-100 to -150 meters Ota and Machida (1987) Japan Bloom (1977) Global compilation

-135 meters Chappell (1987) North Australian shelf

-150 meters Chappell (1987) North Australian shelf

-165 meters Chappell (1987) North Australian shelf

-150 to -160 meters Ota (1987) East China coast

Maximum submergence in the offshore south~tral California coastal region may be slightly in excess of the eustatic rise in sea level; thus, elevation of submerged low stand strandline would be lower than global average (Clark and others, 1978). li

f'r QUESTION GSG 3 xiii'5 6 i based on rekrtive~~displacement ofthe basement, top of'Miocene, thc mid-Pliocene dlscontiruuty and thc post-SVsoonsin low stand, fnehtding thc uncertainties In thc analysis. Ahe kt m~ K 6~~8 B i i i meters, in Table 9 and Plate 5 ofthc Rerponse to Question 49I, but as -M7 and -INmeters in the discussion, at the meering ofJunc 14, ofthc north Estero Bay slope break. Ifthe lower vrdue Is correct, provide thc'ubDshed source or othe supporting data for this ckpartrrre from globally established values. Ifevkknce supports both thc lower value to thc west ofthc srrrfaee scarp ofthc Hosgng and thc'apped -120 meter level near thc Hosgri scrrrp, discuss thc mte oj>ettleal fault slip thereby implied.

CONCLUSIONS

~ Maximum vertical rates of separation

0.11 to 0.40 mm/yr post mid-Pliocene

0.08 tv 0.39 mm/yr post top-Miocene

rates include coastal uplift and deformation of Purisima structure

~ Up to 72 percent of basement serration occurred during pre-Top Miocene deformation

~ Late Wisconsinan low sea level stand cannot be used to assess vertical separation

does not cross Hosgri fault zone

uncertainty in published sea level elevations that range from -80 to -160 meters

uncertainty in map location and lateral continuity

~ Shelf break in Estero Bay appears to be composite scarp formed by wave erosion and deposition during multiple low sea level stands f

ggl

c 4.

If~ Q

i .QUESTION GSG 4

Prole lhe analysis ofthe:ttpllP rtttes across the'Hosgrf ~ the Ltteral Act df46splaeetttent, and thc mart'ations along the iength ofthc Hosgri as discussed at thc meeting. Include thc basis for their mcasurcmcnt, thc uncertainties, and a discussion ofthe geometry ofthe fault and its effects upon the cwluation ofthc cortical and horizontal displaeements, Also sununarize thc evidence for strike-slip and dip-slip along thc 15 kilometer reach ofthc Hosgrt'ault that estendsPom the westernmost scarp at 59- meter ridge northward across thc north Eerie Bay sloptt break and expiain how the geometry ofthc 30-meter high, scarp-like, part ofthc'orth Estero Bay slope'reak can bc'erived by right iaterai striWslip.

APPROACH

~ Compile rates of vertical and lateral separation

geophysical data across Hosgri fault zone

coastal uplift rates

San Simeon fault zone

San Simeon/Hosgri fault zone

~ Calculate ratios of lateral to vertical components of slip

spatial variation along fault zone

.consider regional tectonics

~ Given slip rate ratios, evaluate fault rake and sense of slip

~ Evaluate origin of North Estero Bay slope break

clarify location and elevation

Northern San Luis/Pismo San Luis Obispo Point Sal Southern Reach Reach Bay Reach Reach Reach

San Simeon- Southwestern Hosgri Los Osos Boundary Casmalia Lion's Head Southern stepover fault zone faults fault zone fault zone Terminatio, l l

~O Preferred t Hosgri and Purisima 0 H:V H:V ':V H:V t H:V ) > 5 10:1 to 30:1 l 2:1 to 11:1 l 2.4:1 to 14:1 l >1:1 to 18:1l >1:1 to >7:1

~rz~~atta Post-middle Pliocene (2.8 Ma) horizontal slip rate Maximum post-middle Pliocene (2.8 Ma) vertical slip rate across the Hosgri Fault Zone Maximum post-middle Pliocene (2.8 Ma) combined vertical slip rate across the Hosgri fault zone and Purisima structure

Hosgri Fault Zone southward decay of lateral slip

+o 1Q SOUTHERN Stepover 1-3

COAST

L OS RANGES j o~ DCPP +Op r

C~ 0 C~ 0/g~ ~ Lions Fwtt

+up X5 2'pe R e 20 mi ++ga

20 km WESTERN TRANSVERSE RANGES 'I ~

[J HQRNAFIUs: TEGTQNIc RoTATIQN oF TIIE SANTA YNE7. RANGE

4fjX

Late Miocene Present

Fig. 12. Development of the present-day fault geometry and fold pattern within thc Santa Maria basin, as a conse- quence of post-Miocene clockwisc rotation of thc Santa Yncz Range about an castcrn contact point (dot). Termination of Plio-Pleistocene strike-slip displacement on the Hosgri fault was accomplished by N-S compresslonal deformation with;n the Santa Maria basin, to the east ol'hc fault.

San Simeon'oint

0 5mi

0 10 km

'I +g > 4 + i '.:. Point '.:,.~F a,i ~ ' Estero

PA C IF I C

OCEAN

~no Bay

EXPLANATION

Fault; dashed where inferred; sawteeth on upper plate of a thrust fault

Regional break in slope between middle and . Point Buchon outer zones of continental shelf Diablo Canyon Northern Estero Bay slope break (Niemi and Power Plant others, 1987)

Pont San Luis U The shell break in this region is a two stepped profile. The base ol the North Estero Bay Slope Break marks the bottom ol the steeper, more prominent upper part.

59 ridge

( ~~(0 The shelf break is a broad, poorly defined feature in the region southwest ol the elevated 59 Meter Ridge area.

%% 'Ltt, s l f If

8 Sooloor hhecion LINE CM-35 150lo 150m 124 m 75 70 65 60 55 50 45 0.0 -0.0

0.1 -0.1

0.2 0,2

0.3- -0.3

I- 1 >. 04 -04 3 0 0 0.5 -05 g

0.6- -0.6

0.7- -0.7 l

J:,( 2, ~

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' Macfsh rt. Cnw«41 ~ 4th 'v ' 144 411 44'a «41'r e 4 m I 1'cl'&,tr'eel. ~ I '111 vh,vaav hl " 4 ~ rff wa 4 hivranl Iw 1 ~ rvh ec has'l1, ~ «I 'N I ~ t'«1' „4 'N ~ 4' ~ rh .Cr'

- ~ .~'rvr« Ac Athvn r «vr»vrar» tshhrr aff« 'vhv4m P4 wvvat r'.

t l

+i Base LlNE CM-45 ~ 165 m 01 05 10 15 20 25 0.0 0.0

0.1 0.1 c 0.2 0.2 'g O CJ

0.3 0.3

0.4 0.4 0 0 0.5 0.5

0.6 0.6

0.7 0.7 Y

'i~ ~ I I I I MWSIPNINNININNWNHNIIMNSNSNONMHWNWWNNMMeltmuuutmuhultu~t~llI SNNuululuhhulun WPWIINPIUNMNNNMWhnlumtuPIPNININUNPNSNuh Nlu nut NSINNINIHllultuNININISINthlluuuuun,uuulluuulMtl Ntuuhu Nt OSIMMNIH IwNNIIINNlhhINPIINHINIIINNNHIINIhMNSNINNNHIINIHIIN Wuu PNPNNIN INNWNNNIPIWWMNINI IIIPIIIIIHIIIIIIIIININWIINNNIPS NINSIIIIIIIIIII IINNIHNIIIIIIIIHHINNII mlhultul NININN h IIII NN NNIPIIIIPIIS44114 IIIIPHII IHINMPPHNIhNINN WHSNIHNNSNNNINNNNNNNNNHINHMNNNHINNNNNNNWSNINIHNNNHN Nhu INISNMNNININNIN Nuu NNNI WNNII HI IIIIIIINW NISINIIIIINNIsNINNNha INNIHNINNN lnmhmwnlwhhm NNSII4SIIIININPNIPNHININIHIIhWINHINIISNIIINININSNNISM NMNIMI INWNMUSI~INSIIIIININIPSIIINI ~IIIOPNNNIMMINPHIINSMNNNNNNWIINWMMPMSHPNlul luuunMulffu uumuut NNNWItuWMINMSIINI'PSPV ~ IHIhh uuHSNWWNPSMIWNSMI OSWIINNI INPINHIN IIIPIISNllIIIINn IIIP Nu IulIIIIIW HIINIHIW NIWIIIIMIhunuhumunhllulhhMMNIMINIMINMIMNPMMINSMNÃlttl'IdummmutluntnnNnu uhlhlmtmhnuthu u ISVVPWI~VSVntnrrn elNINNMNHHNNNWI SNNSIPI I '4 mnmvnvhmheeumutppppnt ~ ~ tlhnshpmunvumrt nn ~ rr r uh ~ ~ ~ ~thhWIhhhSNA sus,'LhhhhhhhePuutnhtmihrlsas!4 thunIMH NNNpmmunhmnummpumhmmntMNHuluppmmnummuhhhs uhtpuuwmu'tdhsp tv.tpr A» ININONNIIINN Mpnsmulw «uhnw 'IWNINISNINNINN SI SNIINP ISIHNWI Wlrtlnuum NIWWIWIINWMMI ~I\I NlulhuuulhlluuluPIN m~se ils'M'ehm Iru u 'trteuhrt.es nests Mulnl hnlhuuhPWrMNnNPuuhemuhmdlhh s ~ SPutsr ~ 1'"-, ~ ~ % ' Ph P SNWNnshumttumhmnmuhtnthhrn '44 Weteu Uhnhuh Pmhh hhhIPMO ~ hn h J VSSE'u SV. tAt r ' 1 ri L VVI ~ hsnmhmdut Ntmk'luun nn I A ~ tmrumlwmhrrnlwwpstu ~ M~smmmm

urntnmk'hnl

~'\hit AI up

' rel ', «rnwmsnnhswlhmhue p

'uplle " I .Netvnhpspstpltllo @II MjehhlNw M Is'4 'lhttl Natal ll'+4 ~ end tsultrtht held phl su,tech ntl Ip I\ddt" I IP 'hnel" «pjl uen44 4 aph ~ gpnhelhs» ( pueuut ~, I ~tp I'Il" 4 1

~1'k

Jt JL 'L.

A QUESTION GSG 4

Ae vuk the analysis ofthc uplijl rates across thc Hosgri ~us the lateral tete ofdisplacement, and the nrnations along thc length ofthe Hosgri as discussed at rhc meering. Include the basis for their mcasurcmcnt, the uncertainties, and a discussion ofthc geometry ofthc fault and its egccts upon the neluation ofthe venieal and horizontal dlsplaecmenrs. Also sununarizc thc evidence for strike-slip and dip-slip along the 15 kilometer reach ofthe Hosgri fault that estcnds fiem thc'esternmost scarp at 59- meter ndgc northward aaess thc north Estcte Bay slope break and esplain how thc geometry ofthe 30-meter high, scarp-like, part ofthe north Esrcro Bay slope brcak can be dcri md by right-lateral strike-slip.

CONCLUSIONS

~ Ratio of lateral to vertical slip ranges from —2:1 to —30:1

lateral slip rate 1 to 3 mm/yr from San Simeon fault and San Simeon/Hosgri pull- apart basin

maximum vertical slip rate 0.1 to 0.4 rnm/yr from mid-Pliocene unconformity and coastal uplift

~ Ratio may decrease from north to south as lateral slip is consumed by crustal shortening in Los Osos/Santa Maria domain

may approach 1:1 south of Point Sal assuming minimum lateral and maximum vertical rates

"...the sense of slip on the Hosgri fault zone may change along its length, ranging from more purely strike-slip in the northern reach to perhaps equal components of strike-slip and dip-slip towards it southern end... (p. 2-108, PG&E, 1988)

~ North Estero Bay slope break and shelf break in Estero Bay are not generally coincident with the Hosgri fault zone and did not form by either dip-slip or strike-slip fault activity 14

I j l

ghvi QUESTION GSG 5

Provide the tsunami analysis used to determine the location, moment, and magnitude of the 4 1Vovember 1927 "Lompoc" earthquake including the uncertainties, and the letter from Dr. Abe pertaining to his tsunami magnitude deternii~iation and the Hilotide gauge recording. Discuss potential timing errors that arise from clock error, marking error, or other causes inherent in the San Diego or San Frarrcisco marigrams. Describe how the tsunami analysis technique has been calibrated against data.

TSUNAMI ANALYSIS OF THE 1927 LOMPOC EARTHQUAKE

OBJECTIVE: estimate the location and seismic moment

APPROACH: waveform modeling of recorded tsunami

Location: use travel time and waveform shape

Seismic Moment: use waveform amplitude

Validation: use reciprocal path from the 1975 Kalapana, Hawaii earthquake to California to test accuracy of travel time and amplitude calculations 1 '

f V, 124 '123 122 121 120 '19 '18 117 116 39'N

Fort Point

38'00 California

g O o O ~ oo 37'5'ong 000 ~ (o Port San Luis

Beach 34'a

Solla 33'

32'XPLANATION

—1000 — Bathymetry contours in meters Station location

Area shown in Figures GSG Q54 0 and Q5-5 I

I '

' 157'W 156 '55'54 '1'N oo Maui

Hawaii 20'ilo

Kalapana

800

0 19'ooo

18'XPLANATION

—1000 —Bathymetry contours in meters Station hcation 1975 Kalapana earthquake

COMPARISON OF OBSERVED AND CALCULATED ARRIVALTIMES AND AMPLITUDES OF THE TSUNAMI OF THE 1975 KALAPANAEARTHQUAKE

Arrival Time (h:m) Amplitude (cm)

obs. cal. obs. cal.

La Jo11a 5.37 + 2 5:35 20 16

Long Beacl> 5.46+ 2 5:47

Port San Luis 5.17 + 2 5:14 26 "6 4j'

V> Fort Point

La Jolla

Hilo, Hawaii

EXPLANATION

Arrivaltime of tsunami Ag f( 122 ~V 121 120 119 III II 36 N

35 + Gawthrop {1978) location

+ Hondalocation Long Term Seismic Program revised location

~i20{) 100

P )0 f 600 $ o oo o o 33'

EXPLANATlON —1000 —Bathymetry contours in meters —Best esfimafe of kcos —----- 2-minute uncertainty in travel time + 1927 Lompoc earthquake 1,

'1 ~ ~ ~ ~ ~

~ ~

~ ~ ~ ~

~ ~ ~

~ ~ i ~

~ ~ ~ f

l< t t )4

I Helrnberger's location

10 min 20 min 30 min j

T i",

'z'7

! Gawthrop's location

10 min 20 min 30 xnin

Fort Point observation

Honda

Gavrthrop corrugate

40 60 80 100 120 nwn from 6:00 I . La Jolla observation

LTSP

0 E G anthrop

conjugate

0 P,Q 40 60 80 100 120 min from 6:00 34 ~

% 41

PA Hilo observation 10

-10 " LTSP 10

-10 Honda 2 10

Gawthrop 10

-10 conjugate 10

-10 0 20 40 60 SO 100 120 rrun from 8:00

Fort Poia.t

OBSERVATION

0 -5 z,Tsp (mm)

: urface

0 -5 800 m depth

Honda

L 0 20 40 60 80 100 120 min from. 6:00

La Jolla

OBSERVATION

LTSP (Skm)

surface

200 m depth

Honda

0 20 40 60 80 100 120 mia. from 6:00 I "I l

),f $ t 'I

'4 I

t 1983 Coalinga earthquake

Azimuth to De Bitt station

we Plant~

'I /1 AII OI QI

ompoc

~ants Ba L a~ I ~~

~ sSRS,.Ssiila,Lusts asnrt ....

121o

1927 Lompoc earthquake epicenters Area encloses SSS-S and pe Byerly(1930) location estimates uncertainty in tsunami Hanks 8 (1979) location Oo Gawthrop (1978) 0 PG&E (revised) , ~Surface projection of zone Arcs drawn from De Bill and rupture Santa Barbara seismograph stations Surface projection of fault plane glq

P»

i/ + J

lq l, EARTHQUAKE RESEARCH INSTITUTE

THE UNIVERSITY OF TOKYO

ADDRESS 'UNKYO KU. TOKYO. JAPAN (llS) CABLE ADDRESS: 2ISINKEX TOKYO TELEX NUMBERS 272 2I4b(ERl TOIQ

April 28, 1 989 Dear Dr. Kenji Satake:

Some years ago, I received- the same questionnaires about the Lompoc tsunami of 1927, one from Tom Hanks and the other from Robert Page. There was a concern, at that time, with respect to the nuclear reactor. They recommended me to study further, but I have not, though I am still concerned over it. Do you remember that I previously summarized this pic at the seminor in Hokkaido University '? I rigorously ained Mt=7.6 +/- from the records at Hilo and Honolulu in awaii. In the late study, I found that records in California give the smaller estimate, i.e. 6.9, as far as my method for use of local tide gage data is applied to the records. This difference between the near-source and the far-field Mt is suggestive of a strong directivity, but I am not confident of discussing any more without detailed study. It is quite interesting that only the Lompoc tsunami was recorded at the Hawaiian Islands across the Pacific.

Sincerely,

PP 5 () J

K. Abe xc: Prof H. Kanamori E

l4 CONCLUSIONS:

Both the travel times and the waveforms of the tsunami indicate an offshore location compatible with that derived from seismic waves

Locations beneath water shallower than 200 meters, including any location on the Hosgri fault, are incompatible with the travel times and waveforms

The seismic moment derived from tsunami recordings is 3 x 1026 dyne-cm., corresponding to a moment magnitude of 7.0.

The tsunami magnitude of 7.6 derived from Hawaiian recordings by Abe (1979) reflects strong bathymetric effects, especially near Hilo, that were not taken into account. Abe (1989) obtained a tsunami magnitude of 6.9 from California tide gauge records

Waveform modeling that takes account of bathymetric effects gives seismic moment estimates in Hawaii and California that are consistent with each other

QUESTION 6

Provide a discussion ofthe felt data for the 4 November 1927 mainshock and the aftershocks and how they relate to the proposed locations. Zhe isoseismal maps of the 4 November 1927 and the 29 May 1980 earthquakes were compared and based on the companson arguments about the location ofthe 1927 event were made. It may be inappropriate to make this hnd ofcompanson since the strikes ofthe faults as determined from the focal mechanism studies appear to be diferent. lee differences in the radiation patternsfor the two events could cause diferent felt data geometry even ifthe events were in the same location.

APPROACH

~ Review intensity data for the 1927 earthquake

~ Evaluate intensity data with respect to the 1927 earthquake location

~ Compare intensity data with other regional events I

s ~

,1 I

+'(

$e ~ 5 ANGER I pREgLEY GONZALES ~, N ioOROSI 1 SELMAQq ll,N ~~OEZ w'V ~H~RD OV5AUA I N WG aTYe I 41%%ST J ~ TNARE 3 'l SAN LUCAS'S \ ~r ~ PORTER VILLE 36 +' 'lg I PARKm)~i-s<] ~ SAN h4QXL~ SHA~ONg(jQ(AME ~ KERNVILLE ~ 5ABELLA 4 'I CAMbRIA HARMONYelTEMPLETON ~ OSCRESTON i- yS + ATASCAOERO 6 7 y8UiloNwlllolrg~p~~ 5 6 1EHACHAPIPOZOO~ / N 5 I S yMcKITTRICK / 6-7 c l STAFT f ~ MOJAVE 5o HAL 77 7 ~ ~ s-7 PArTIWAY y ~ I 4-5 ~ 7 bETTERAAA .N T -GORMAN' TKHARR5TONY ~LOS ALAMOS SQÃFERy 7 v 04-11-1 927 SCHEGECK ~y g IjfNSAMATI4R ~ PALMOALEO 'LAS Cem 3WAXIER ARLIGHT ~~g6+ l 6 FLLMORE GAVIOTA - I ...,"- ~TERIA 03-'4 P~ NAPLES 4 ~ ', F SANTA bARSARA ~~ ~SANTA PAULA 5+ Pacific — Ocean 5 6 r.- GLENDALE 0 ~ r' N C ~ 34 LOS ANGELES 5 F WHITER SANTA MOhKA 3'4 LONG EXPLANATION bEAOI REOOhOO EEYUCH 5 N VICENTE 3Q mt ELK Intensity location of Evernden and others (1981) TQ fntenslty location of Toppozada and Parke (1982) SAN PEDRO 40 km PQ POKE revised Instrumental location 7o Modtfled Mercalll intensity d f20~ ll9 I 'd»' RESULTS

~ 1927 earthquake intensity data are consistent with the PG&E revised location

intensity data are severely limited by the offshore location of the event

relatively low onshore intensities suggest a location not next to the coastline

small felt areas for intensity VI and VIIonshore are consistent with Ms 7.0 located southwest of Point Arguello

~ PASO RObLES 4tRF) '1 ~ bAKERSFIELD 3tRF) SAN LLAS Ob5PO j ~M@ KITTRICK 3-4tRF) I PtSN) bEACH I b 6tRF) ~ P ~X '5 ~)eCICQPA 4tRF) 35 ~SAttTA MAR

30 ml

40 km )20 I)9

EXPLANATION Epbenter 7 ~ Meditled Mercam Intensity i. Ze 1210 120'19'18'6'6'+

1-3 o1-3

~ 1-3

~ 5 35' 35'0 1-3 ~

5 56 e4 6 og ~ 4 8-27-1 '4 ~ 4 4 5

0 30 mi Pacific Ocean 50 km Epicenter

121'20'19'XPLANATION

ee Modttied Mercalti intensity

121

120'19'18'5'1'69

~ 5 ~ 1-3

5 o4 4 5 5 ~5 5 o4 35' ~ 4 ~ 5 ~ 5 o4 ~ 5 ~ 4 ~ 1-3

Epfoenter so Modified MercaIII intensity 0 121 120'19'18'

~ 4 3 ~ ~ 4 o4 ~ 5 ~5

4 5 4 ~4 35' ~ 5 35'

5-29-1980 > 4

~ 3 3

30 mi Pacific Ocean 50 km

121 .

120'19'XPLANATION

Epicenter so Modified Mercalli Intensity It

~ ) ~0 I ~ ~ ~ ~ ~ I) V A I) ~Aa+@ ). * I~ I 10 ~, IV ~

~ ~ ~ ~ ~ I ~ ) 4 n-m "., ) I ~ ~ ~ ~ ~ ~ ~ ~ ~ 'I I ~ ~ ~ ) 11 I I I I ~ ) II ~ Rs I ) I ~ ) I ~eeeog ~ ~ I ) ) ~ s Vl'

~ ~ 1 Figurc I G ~ 11 'I ) 06-7 V )~ ~ ) ~ I ~ ~ I C'A I.III)RYI A g>)) lv IV I 11

0 60% KIPLANATX)II *Eocenl« ~ IVIH tlWWtfR 0 100 km yJ 15'I 5tOO ~ 5

~ ~ ' Vl

'5 le e~e I h ~ ~ A' eee

4 ee l V

~ ~ l Z ee ee Vll ~~~ f g I /, Xheleeee / t4 4r ~ gee Ceee

l ~ 4 V

f~ANA1IQII *fpC»el» ~ F»I CI »lohPt'f 5 J 0 10mi J.

~ r.@RELYII a OOROSI r ~~DEZ ~ sr ) 1 ~ HA!4QRD OV5AUA J KNG PTY J oTRARE s: OCOALNGAr SAN LUCASO yrs sr Y L \ 36~ o ~ PORTER VILLE .. SANAIIDK~ +' 1g PARKaOO < W I 4-5 P \ Z-E ~ KERNVILLE sssrrrsrsMplsroN ~ j g ATASCADERO ~SUTTONWILLOgbAKERg:OLD gQ 5-6 ~ ~ ~ RPARD 5 5 6 ~ O~ 5 OMcKITTRICK SAN LQS 7 g44 LAPAHZA l rsssr srsr L ~s-s ! ELLOWS s 6-7 -.-.-~f y soTAFT TEHACHAPI l ~r> ~ NNS~~ i o5$ ~5 7' / ~ OJAVE 35'AL ~II feI GUADALrss A Vw~rA / ~ Ir7l \ fAmWAY f I-~ 7 bETT8IJSJIA 'I. gs r ssss'sst f —- - -.-GOR~ ------— 5 4NFERO a5 T@HARRIstoN> > oLosr ALAMos 04-11-1 927 s KHEDKK sr sr s SsgssssrsrAVM'2 ~ 6 7 PALMDALEo Wf45 LAS CRUCES 6 C CONQFC ION PaLMC4 GAVIOTA /- CARPNTERIA ~ ~ SAUGUS Pg NAPLES o SANTA bAIIARA 4SANTA PAULA PASADENA Pacific Ocean r ~ N LOS ANGELES ~ 5 F WHTTER SANTA MOCHA 3'4 34'0 LONG bEAOI EXPlANATION REDO')O KACH ml ELK lntenslty location of Evernden and others (1981) TQ lntenslty location of 7oppozada and Parke (1982) 40 km PQ PGILE revfsed Instrumental focatfon 7o Modified Mercaiil intensity 4 120i ll9 I ,4 Table GSG Q6-1 FELT REPORTS OF FORESHOCKS AND AFTERSHOCKS OF THE NOVEMBER 4, 1927, EARTHQUAKE

Time of Event P-wave Tim and L cati n f Fel R rts Timed

Nov 4: 3 AMLompoc, Santa Maria, San Luis Obispo 313 3-3:30 AMLompoc 5:51 AMMain shock 5:51 6:12 AMSanta Maria-. 6:11 6:14 AMSanta Maria 6:13 7:00 AMSan Luis Obispo 6:56 and 7:04 7:42 AMSanta Maria 7:44 11 AM(approx) aftershock felt at sea 10:58 and 11:02 t 12 PM (approx) aftershock felt at sea 1?'00

Nov 5: 12:17 AMSurf 00:16 and 00:18 t I:00 AMPaso Robles to Hadley Tower I:01 3:37 AMSurf to Hadley Tower (south of San Luis Obispo) 3:34 4:06 PM Buellton 6:25 PM Lompoc (strongest event) 18:39 7:10 PM Buellton 19:11

Nov 6: 2:10 PM off Point Conception 14'l l

2:50 PM Buellton , 14:51 3:10 PM off Point Conception 15:05

Nov 8: 2:02 AMBuellton I:58 ?'15 AMLompoc

Dec 5: 3:45 AMBuellton, Surf, Guadalupe, Santa Maria, Santa 3:50 Margari ta

Dec 31: ?'10 AMPoint Arguello

Diablo Canyon Power Plant tong Tenn Setarnto t'rograrn

RESULTS (continued)

~ Intensity data comparisons with other events in south-central coastal region reveal azimuthal variations in isoseismal patterns

azimuthal variations may be related to crustal structure, source radiation, and local site conditions

data are not adequate to refine and resolve these factors I

~ Felt data for aftershocks are consistent with the mainshock intensities

felt aftershocks are also instrumentally recorded

aftershock intensity data are limited, generally locally reported V

(4 QUESmoN 6

Provide a discussion ofthe felt data for the 4 November 1927 mainshock and the agershocks and how they relate to the proposed locations. Theisoseismal maps of the 4 November 1927 and the 29 May 1980 earthquakes were compared and based on the comparison arguments about the location ofthe 1927 event were made. It may be inappropriate to make this kind ofcomparison since the strikes ofthe faults as deternined from the focal mechanism studies appear to be diferent. The differences in the radiation patterns for the two events couM cause diferent felt data geometry even ifthe events were in the same location.

CONCLUSIONS

~ Intensity data are limited due to the offshore location of the 1927 earthquake

~ Mainshock and aftershock intensity data are consistent with the PGEcE revised location of the 1927 earthquake

QUESTION 7

In U.S. Geological Survey Professional Paper l223, Seismic Intensities of Earthquakes of Conterminous United States-Their Prediction and Interpretation," Everenden, Kohler, and Clow used the observed intensity dataPom the 4 November 1927 earthquake and their predictive model to evaluate several estimates ofthe epicenter, fault length, and fault orientation ofthis event. 7he authors conclude that, ifthe general applicability ofthe predictive model is accepted, the intensity dataPom the Lompoc earthquake require a location on or very near the Hosgri fault. Provide a discussion ofthe conclusionjom this study in light ofPG&E's analysis ofthe earthquake.

APPROACH

~ Review Evernden and others (1981) analysis

~ Assess applicability of and sources of uncertainty in their analysis

Evernden and others (1981) Analysis

Input parameters

Location offault Fault length and orientation Attenuation parameter Depth offocus Site geology

Output parameters

Predicted intensity value at each site P~

Agee

L„

/)l'

E aYoeendPr ~ reeyaato ~ Qs1paa

Pab Aio

HoSerer ~ ~ eaecrrr4e I ~ Sednee / Queer Seine ~ Oroel 0 50 km Cannel e gone rdee ~ Srdedad ~ Id' Sly Sor Hemadez

~ Trdere Pdeel Yaley

Lockwood ~ ~ Perklekl

~ Chokrne K ernie hebeaa e ~ Ade4Ma Annene ~ P~ Aoblee ~ Araeck~ Sorkrnwllow CefUcoe ~ Sireraer e ~ ~'e Sa„~ ~ Pore Parcra QdOekk

Hosgrl Fault Zone

-Vl ~ V-IV Sca. l4da Vll P~ Point Sal o Skeered Sroodere gt aX p ~Schekbck 'e~ Wheerer ~) ~ P Point Arguelto Sprays Saraa Parda

PG8 E revised 85'10 hcation Qverre Porrcrna e ~

Aedondo PL Vina' 12V r

t * QUESTION 7

In U.S. Geological Survey Professional Paper 1223, Seismic Intensities of Earthquakes of Conterminous United States-ZAeir Prediction and Interpretation, " Everenden, Kohler, and Clom used the observed intensity data from the 4 November 1927 earthquake and their predictive model to evaluate several estimates ofthe epicenter, fault length, and fault orientation ofthis event. Vhe authors conclude that, ifthe general applicability ofthe predictive model is accepted, the intensity datajom the Lompoc earthquake require a location on or very near the Hosgri fault. Provide a discussion ofthe conclusionjom this study in light ofPG&E s analysis ofthe earthquake.

CONCLUSIONS

~ Intensity data for.the 1927 earthquake provide inadequate constraints for the Evernden and others (1981) inversion for event location

inadequate short-range data

inadequate azimuthal coverage

QUESTION GSG 8

Ef the seismograms from the Santa Barbara Wood-Anderson instruments are available for the 4 November 1927 earthquake, it may be possible to get an accurate azimuth from a vector analysis of these horizontal instruments to help in establishing the epicenter. Also, re-read the S-P times from all the Santa Barbara records for this earthquake. ~II

~ j

et REGIONAL SEISMOGRAM ANALYSIS OF THE 1927 LOMPOC EARTHQUAKE

OBJECTIVE: estimate the location

APPROACH'ongitude: use S-P times of aftershocks recorded at Santa Barbara (following Hanks, l979)

Latitude: use back azimuth from Pasadena

Location: from intersection of Santa Barbara S-P arc and back azimuth from Pasadena

Validation: use S-P times of more recent earthquakes off Point Conception to calibrate S-P time vs. distance; use back azimuths from Pasadena of more recent earthquakes C

p+) -j~

~k. Y L 1983 Coali

l I / Ol/ OI Oi

o >0) /. I~ eLo-m—p.-o-.c- ,I M'~ta Ba ~J \ B~g i I "~ e.. ","..." - ~ .. ~ 'SOS,.Santa .t.ucia Bank ... " ~ -- Santa Barbra he ~ S'%ST,~nga

121'

EXPLANATION

1927 Lompoc earthquake epicenters 0 Earthquakes 969) Qe Byerly (1930) a Santa Lucia Bank (10/22/1 8 Hanks (1979) b Santa Lucia Bank (11/5/1 969) Qo Gawthrop (1978) c Point Sal (5/27/1 980) Q PG8E (revised) d Point Conception (08/27/1 949) Arcs drawn from De Bitt and Santa Barbara seismograph stations

S, this paper

S, C IT

Table GSG QS-1

Ts p TIMES OF THE NOVEMBER 1927 LOMPOC AFTERSHOCKS RECORDED AT SANTA BARBARA (SBC)

Ts-p CIT Li& Date TlQle (sec) (sec)

11/04/27 10:52 12 12.2 16:17 16(~) 13.9 19:28 11.5+ 12.0 20:06 12.0 12.4 20:43 12.0 12.6 21:30 12.5 14.5

11/05/27 19:00 12.5 1 1.7 20:26 12.8+ 12.2 20:51 13 1 1.8 20:53 12.0+ 12.4 20:58 12 11.5 23:09 12.1 124

11/06/27. 01:05 134 13.4 » 02:29 12.5 12.6 02:40 13.5 14.0 02:49 12.5 12.5 04 49 14.5 14.7 09:11 14 12.4 09:39 12.0+ 11.9 '2:02 12 11.8 17:27 13 13.0 23:02 13 13.3

11/07/27 01:30 12.5+ 12.6 03'43 13 14.4 04:55 14 13.8 06:20 13.5 13.2 07'17 12 15.1

NOTES:

Time is given as hours:minutes and is approximate time of aftershock.

CIT is the T> p time as it appears in the Caltech unpublished tables.

LTSP is the new estimate of T> p, yielding an average of 12.9 seconds. gt 16 ~ / / / 0 / 15 / I / I I 0,/ I 0 / I 0 I / I / 14,'— 0 / / I 0 I I I / I 0 0 13 .0 I / 0 I I o, o 12, O ll / I I / I / I / / I 10 ~ I 10 12 13 14

CIT Ts-p (sec) 'I

l'~ Table GSG QS-2 S-P TIMES OF RECENT EARTHQUAKES OFF POINT CONCEPTION

Time Latitude Longitude Depth Mag- Ts-p No. (Figure Date hr:min sec ~N ~W ~km nitude G~GG 8-6 07/18/80 05:14 50.99 34 34.00 120 41.95 4.75 3.00 12.7

05/10/85 15:48 00.34 34 25.12 120 45.60 7.64 3.69 11.8

11/23/86 02:08 59.77 34 17.69 120 39.30 13.27 3.07

02/27/87 22:43 19.32 34 31.00 120 46.51 0.00 3.61

08/06/88 05:35 10.86 34 30.46 120 48.59 12.21 3.00 13.1

09/24/88 07:33 44.60 34 24 45 120 47.77 13.19 3.20

01/09/89 23:01 17.16 34 29.61 120 43.73 9.11 4.00 12.3

01/10/89 00:34 37.65 34 25.25 120 45.15 5.64 3.00 11.6

01/10/89 12:45 42.32 34 28.97 120 42.38 8.67 3.10 11.2

/10/89 17:21 21.51 34 29.64 120 41.52 4.38 3.10 11.1

04/26/89 14:47 10 40 34 26.79 120 46.29 5.95 3.80 12.3 10

NOTES:

Illegible seismogram No time marks Time period: 1980-1989

Magnitudes: 3 or greater

Latitudes: 34'5'o 34

35'20'35'o Longitudes: 121 10' ~ a 4I

~ 0 ~ ~

~ $

1'i- J' Nt '

1983 Coalinga earthquake

Azimuth to De Bilt / stadon

\ Di io Canyo

'rt i~ 1 I tr OII OI t A )g

t - ~~PQc I/ ~'ttznta Ba

~ ~ ~k azlrnurh

~ S~.~ta t ana Bank..." SRSS ~nga

121'XPLANATION

1927 Lompoc earthquake epicenters O Earthquakes 969) Oe Byerly (1930) a Santa Lucia Bank (10/22/1 8 Hanks (1979) b Santa Lucia Bank (11/5/1 969) O~ c Point Sal (5/27/1 980) i Gawthrop (1978) 0 PG8E (revised) d Point Conception (08/27/1 949) Arcs drawn from De Bitt and Santa Barbara seismograph stations

East-iVcst North-South

Lompoc Mainshock 11-04-27 W-A .8sec

Lompoc Aftershock 11-05-27 W-A 6.sec

Point Conception 8-27-49 W-A 6.sec

Santa Lucia Banks 11-05-69 W-A .Ssec

i8 888SEC

FOR NS time shift. = -0.2, -0.1, 0.0, 0.1, 0.2 Point Sal 1-90 NS time shift = 0.0 FOR angle = BAZ-40 to BAZ+40

Compute TAN from NS and EW z N Compu(c — TAN; T g 2:+i( next angle N Save minimum — TAN; E: its BAZ T g

250 270 290 310 330 next NS time shift Back Azimuth, flI

4 Back Azimuth 0 0Ch 0~ Oo0 0m 0

8-27-49 PLConccption

10-22-69 SantaLucia Banks

11-05-69 SantaLuciaBanks

5-29-80 Point Sal

11-05-27 Lompoc Aftershock

l I -04-27 L()mpm: Mainshock

NOD h g g td p] 'a O Q CA h D

O ~ ~ O cn + o+ o 0 t. Q4 CA ~ ~ wi ~ ~ A 0 CA '

I i1

~ L 'v 1983 Coalinga earthquake

we Plant~~,.

1 I / I Ol ;',). C . OI ~~l Pt. Sat '. "")

I ( ', ''~ inta Ba

~ I ~lQQ li orn pa~ en a 'L .,"". " ~ ... ~ 0 20 km SS!M,~;t;acia Bank..." -"--"..., ., Santa Bartaas aao ~ a &SSs~nga

121'XPLANATION

1927 Lompoc earthquake epicenters 0 Earthquakes QB Byeriy (1930) a Santa Lucia Bank (10/22/1969) 8 Hanks (1979) b Santa Lucia Bank (11/5/1969) OG Gawthrop (1978) c Point Sal (5/27/1 980) 0 PG8E (revised) d Point Conception (08/27/1 949) Arcs drawn from De Bitt and Santa Barbara seismograph stations

CONCLUSIONS:

Our readings of S-P times of 1927 aftershocks recorded at Santa Barbara agree with the CIT times used by Hanks, and are calibrated against distance by more recent events

The latitudes of more recent events are reliably estimated from back azimuths from Pasadena

The longitude constrained by S-P times is 120.9'.

The latitude constrained by the back azimuth from Pasadena is 34.35~ N.

QUESTION GSG 9

Tite seismogenlc structure on which the 4 Nonrnbo &27earthquake ocesrred shouid be ident tJied and esnlunted for tnaxitnum earthquake potential and its closest approach to the Diablo Canyon site. Account for this in both the probabillstlc'nd the detetminlstie analyses.

APPROACH

~ Summarize structural setting of the 1927 earthquake location

~ Establish structural association of the 1927 earthquake

~ Characterize the Santa Lucia Bank fault as a seismic source

deterministic and probabilistic analysis ~a"

j~ y' 'j g1

36o

~ ~ ~ ~ +o ..~

~ ~ ~ res' ~ oo ro , ~

', ~ Offshore , ~ '> I ~ I l I /

35' I r ~ r ~ rere Pt. Sa '"" ll' ')X)g ClismsltIFnull 8 t(, +~ ~ x od ~,o ~ X StcllctUcd W+„Fd Ult

'K x% '"'" ~" r~ t ii ~ re,~r n re' e gS

1927 Lompoc Earthquake 0( ~RU-10

'll, 0 20 km 34'220 121o 120O EXPLANATION ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Marine reflection line Airgun refraction line Sonobouy recording High explosive shot Refraction recorders Seismograph station Note: Base cnap explanation provided In PGK E (I988. Plate 3). 0

k'~Vs 1971 1955 1985

360

APril 1g EXPLANATION 1981 Limitotg

1999 1919 ) ", 19'c \ '986'. \ 1969 3EMcS

197S~ ~ tlrat~otlon Piota White —Dilation I Black —Ccmq~salon I I '19&2 Oct. o+ >1969 '.~e '0Z q +"-'-t999 "~ 0 (9 'L )

.1969 r

0 20 km

121'

Diablo Canyon Power Plant 8

5~ 125' 124'23e 121' MFZ ~ ~ ~ ~ ~ s s ~ s King Range s s

~ s e ~ e s e EXPLANATION San ~ ~ Simeon ~ Psieosubduoiion zone s ~ Sinks slip Point Arena

F~ ~ s S~

~ e s

s ~ e San Gregorfo Fault

e ~ 3T sr San Simeon Fault

~ ~

~ ~ e ~ ~:: !,', 0/y'.:.:.:.:.:. Sari - ~o>:i::::::,, + Simeon e Santa Lucia-Orocopia Allochthon ~ ~ s rr Sur-Obispo Salinia 4' e ~ Composite s ~ +ps s e s e s rr spS s e e e e San Simeon Stanle Mtn. Gy 125'24'23e M~gnrr

122'21'20'odified

from McCulloch (1 987) C

Ng ~ p

~C .

l' Chapter 2 Page 2-68

374 0 ~ 0 ~ ~ rf, f% ~ o 0 ~ 0 ~'o ~ 0 Do ~

e 0 ~ ~ ~ 0 0 0 yo ~

~ Oo ~ ~ 6 ~ ~ 0 o j Ob g ~ y ~ ~ ~~ ~ ~ a ~ %. (q~ XgC 4». ~ ~ 0 0 r ~ ~ 0 ~ ~ ~ fbi Oe q 0 ~~ ~ ~ '.o 'o

Oye q 0 0 ~'0~ P" ~ h

t I I IIJbgnitu de I 35' ~ 0.0 —0.9 I I X ~ ~ 1.0 —1.9 I o 2.0-2.9 q Ox ~ ~ 0 3.0-3.9 ' Oo 4.0 -4.9 5.0 —5.9 6.0 -6.9 e

0 o 0 ~'""0 ~/ 0 00 0 20hn c4.""

'21'

~ .Diablo Canyon

IZ ~ Area of earthqu@ces discussed ln text

NOTE: a~ Inep exp4netIon provided on pleIe 3.

Figurc 2-27 Map of'seismicity data from the U.S. Geological Survey and CaHfoznia Institute of Technology, January 1, 1980, through May 31. 1988.

Pacmc Gas and Hectrlc Company ~

, ~ '> l ~ ~ ~ ~ ~ $ ~ ~ l J l I ~r, 35' I t rnnn ~ re , ~

ke ek ~ ~ ~ 0~' ~ rrn ~ X r~tl 4 ~s<

W, ~ \ g/r ~~r 0 20 km

121' EXPLANATlON ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Merlne relleellnn line p~keln eel~~k Airgun refraction line Q Sonoh y recoHino 0 Hi~ awPlos Refraction recorders i SeiNnogrsptl station ~ Diablo Canyon Power Plant a Magnitude Mw vs. Surface Rupture Length

Strike Slip Faults, 30 Data Points o e 7 tD U ~ 0 ~ ~ cn 6

Mw = 4.90 + 1.24 log(Rupture Length)

10 100 103 Surface Rupture Length (km)

Wells and others, (preprint)

Magnitude Mw vs. Surface Rupture Length

Reverse Faults, 10 Data Points

V. ~ ~ 7 UI

m 0 6

Me = 4.29 + 1.69 log(Rupture Length)

10 100 Rupture Length (km) 10'urface

Wells and others, (preprint)

Magnitude Mw vs. Rupture Area

All Slip Types, 94 Data Points

/ a D

U 6 O

Mw = 4.12 + 0.97 log(Rupture Area)

10 100 10~ Rupture Area (km2)

Wells and others, (preprint)

Magnitude Mw vs. Rupture Area

—+ Strike Slip Faults —* ~ Reverse Faults 8 —a ~ Normal Faults V 7 Ol U

o 6 U w)r~ ~r~

10 $ 00 )0" Area 10'upture (km2)

Wells and others, (preprint) Jl

P( '1"

,l f,

1 t

f i Sense of Sovthem Oflshore basement I separatbn Santa Maria Baslnl~g

H „Q Faugh o

0 rC 0 0 0 ~~ 0 Q 0 0 0 0

0 0 0 0 0 0

ttott,

1927 Lompoc Earthquake . +M4~ (Lat. 34.35'N, Long. 120.

5 ~>a~=.,

Sl'5'N+ 121'rtN

0 0 0 otsOO 0 0 0 0 0 0 0 0 0 0 10 mlles 0 0 0 0 0 15 kilometers

Uncertainty endoses SSS-S Sources of fault data: bcatbn estimates and uncertainty ~ McCulbch, 1987 In tsunami katbn (see Response ~ Wilngham and Kamllton, 1982 to Ouestbn GSG 5) PGaE, 1988

( baC» MAGNITUDESANTA LUCIABAI'QC FA'ULTZONE

65 Reverse 7.35 65 Strike-slip 7.15 65 780 Reverse or S~e-slip 6.93

GROUND MOTIONS FROM SANTA LUCIABABBYFAULTZONE

M i m 34~h ~i'5 ~l~i~n Mw 7.1 km 0.11 g 0.16g 4 10-1

~ Hosgri 10 Santa Lucia Bank I aa/)r 10

10-'0

.25 .5 .75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 Spectral Acceierction 8 to 8.5 Hz (g) t

),I QUESTION GSG 9 arge¹Ic stt¹cture o¹ iWch the'4 Nmentber 1921 attti'tqsake oceanwF should be identijied and evaluated for meah¹ea wWq¹akc"potetuial and its closest approach to the Diablo Cmrpevt site. hccount for this in both the,pnabaMhttc oaf Sc iktet¹sMNfc ttsttt5eet.

CONCLUSIONS

~ Several lines of evidence suggest that the 1927 earthquake was associated with the southern Santa Lucia Bank fault zone:

Epicenter lies within southern Santa Lucia Bank fault zone and close to prominent fault-and-fold couple seen in RU-10. The couple lies along trend of Santa Lxia Bank fault and appears to have similar history of activity and style of deformation.

Contemporary style of deformation along Santa Lucia Bank is compressional, which is same as focal mechanism.

Strike and dip of Santa Lucia Bank fault zone are consistent with focal plane of 1927 earthquake.

Size of 1927 earthquake suggests source structure is relatively large, laterally continuous fault more than 100 kilometers long. There are no other large, prominent faults or folds identified in the source region. ~ Alternative candidate structures are unrecognized fault within Santa Lucia Bank High or fault within southernmost offshore Santa Maria Basin; therefore, Santa Lucia Bank fault zone i's a conservative structural association for the 1927 earthquake.

~ Evaluating the Santa Lucia Bank fault zone as a seismic source results in a maximum magnitude of Mvt 7.1.

~ Deterministic and probabilistic ground motions resulting from the Santa Lucia Bank fault zone show that it has an insignificant contribution to the seismic hazard at the site. r<

R'(

)4'

fgJ' QUESTION GSG 10

Plmkk a ~e ofthe pnerentatiott tnade by Jay ¹nrson. Discttss and neittate any consistencies or inconsistennes ofhis tnodel wbh the PGBE geologic and geophysical Jieid data.

APPROACH

~ Evaluate structural cross section presented by Namson

Theory

Assumptions

~ Evaluate consistencies and inconsistencies with observed geologic data and kinematic constraints in the region

~ Evaluate applicability of model for seismic hazard asseument VQQ ~ ~ ~ ~ ~ ~ 4 ~ ~ ~ ~ 4 4 0 ~ 0 0 ~ 4 ~ ~ rnnr ~ 0 rpe ~ ~ ~ . 0 ~ 0 l00 ~ led SSI As 00 0 ~ ~ 0 ep re 0 en ~ (tI'oc( w ~ 40 00 0 Or ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 0 ~ 0 ~ ~ ~ ~ ~ ~ ~ ~ ~ O 0 4 c ~ ~ epo p~ 0 phoo ~ ~ ~ ~ y 0 O ~ ~ ~ ~ ~ ~ ~ ~ ~ 0 ~ ~ ~ F. ~ 0 ~ ~ ~ ~ 0 di ~ ~ ~ '0 ~ ~ 0 ~ ~ ~ yQ'0 0 ~ ~ ~ h ~ ~ ~ ~ 40 ~ J ~ 0 ~ 4 0 0 ~ ~ ~ ~ ~ ~ ran ~ ~ lrc«(h, ~ ~ d' 't ~ "oe»S:, ~ ~ + 0 ~ ~ ~ ~ ~ l e" ~ ~ CS 0 yp 0 ~ ~ P ~ ~ 4 ~ 0 ~ ~ Ce ~ ~ ~ ~ h ~ Chrt I F 0 ~ 1 I ~ 0 ~ 0 'te 0 h rl 0 0 ~ ~ ~ 0 ~ 0 ~ ~ ~ '''

'eol 0 ~ ~ 0 ~ ~ ~ SLO.:

0 P 0 4~ t hhhhh h 4< 0 ~ CS ~ 0 0 po ~ ~ ~ ~ ~ es so 00 ~ p y ~ 'MOCngen .shy'.'. ch.'h ~ ~ sc ~ Y ~ O ~ 4 ~ Uy ~ ~ ~ 0 4 ~ 0 O ~ ~ c ~ 0 ~ 4 ~ ~ 0 ' 0 4- 0 -.,c tg V.O. ~ 0'tsr '4e ' jSMe ~.. 0 ~ l 0 0 ~ ~ tepee p(norm snocoyenb ~ ~ 040 00 00 eo ~ ep, 0 ~ 0 ~ ~ ~ ~ 0 ~ 0 ~ oo~ cs C3 0 ~ ~

ce 4 yF~~Oyy 0 ~ ~ ~ ~ q 0 ees c( 0 end ((ceps Fonnssbne C ~ ~ ~ e pope ~ ~ ~ ~ Und(been%a(ed Eoonle Q tppec tuceseb nilte ~

Fcaebcm Conpbs end Coesl ((snye OphbRe Cetcymecenyceed sensory(

Und(fwentbled ycen'Cb end ynebsb ccc(n o( I» Se(nbn bbA

" ' R4N~ ~:~ '%~MFW~ E' ~ N~~~Ã~P..

I'la + w ~ ~ + ~ q )q I l~ )r'\ g'l) )q 1) ) )r 1 r r r g o)g ! ) ) +% ) hl s! )g+ %)lr I)1)+ ~ )'1 I )11 a r I )1 W)1) )I~ ~ \1( 1 r+ 1 )ps 1! r)1! ~i !r ( )r! + \I ~ ~ % (I I w ~ 1 I ~ %r ~ ~ ~ I~%\ ~ ~s l~»>1 ~ !r)rl)alp+)l ~ ~ ~ r)%a I

~ ) 8 A

Fault tip Slip

% ' 1 \ ! Ir 1 ~ + )w ~ ~ 1 gal(1(1 I 1 I I(Iq ! ~ q rl)W!s)qil1) Iigb 1~ ~ ) 1) ~ Plr! I 1) ) I ~ )1) w 1 ~ (1)11!'d1 1( ~ ! ! I>r r 1 ), 1)1' 1) Ã~

g~lq y

v KO : Santa Ma a Provlnclal Maria Plsrno Huasna l.a Panza Range Ill Stages Basin Basin Basin Carrizo Plain Area

~ 0 .et a ian Paso Robles Fm Paso Robles Fm n es QTu Garea a Fm Plio- enturian Morates Fm cene ee ian oxen m Pismo Fm eimontian Sisquoc Fm Santa Margarita Fm Santa Trrsp Mohnian 10 Margarita Fm Monterey Fm Monterey Fm C Monterey Fm VI Luisian Monterey Fm Relizian Point Sal Fm Point Sal Fm iso m Obis o Fm bis o Fm Saucesian Vaqueros Fm 20 Lospe Fm Rincon Fm Rincon Fm Tom Vaqueros Fm Vaqueros Fm CD 8r Simmler Fm CJ Zemorrian

CXI Sespe Fm Sespe Fm ~ ~ 0 tH Refugian Ynezlan Oro geny 40 e C Narizian Unnamed o TKu V Strata 0 50 tll Uiatisian Penutian Buiitian c 60 Vnezian Cl O Danian err 6 Unnamed KJu TO Unnamed Strata Creta- Knoxville Fm ii Strata ceous rystal ine KJf Mzgr Franciscan Franciscan Franciscan Basement Jop pCgn Salinian Block 0 Phmo 8astn

Hosgri Fault Zone Mid-Cenozoic unconformity

P Lornpoe - uutlstrns bsn Antonto - Los Atsrnos Oreutl Antkttne Antkllne ylotnt ben Lute Antkllne b byncttne

va a Weel rIP000 raas XIVI a aaaaa a Ia la 1 100 ~ I+ ~ ~ ~ Up~-, aaaa apaaa F00 I / / 'la / / -t ~wtlrpa Sor ~ lala Tlwlr

SI 00 V40 ~aalear a IVIIa~1000

'gag * X i'I'%24)g ( r pP~ P~

~ -1.0 1.0 S-1 neVyt -1$ 40

L%bC~~ QllCOlllNTTSI7 0.5 km eickcning I k wX( I i5 ' -5 / ~ / X / --r---.. C 7 ug -10 // -10 W / -15 0 10 Krn -15 t e

v> i< , 'arq J'eta

p~ ~ * QUESTION GSG 10

inconsbtencies ofhh model with the PGcLE geologic and gmphysical Jield data.

CONCLUSIONS

Namson and Davis (1990) apply fault-bend and fault-propagation fold theory and techniques to evaluate crustal structure in onshore Santa Maria Basin.

~ interpret basal detachment within basement at depth of 11 to 14 kilometers

~ detachment overlain by series of southwest vergent blind thrust faults

We disagree with the crustal model for several reasons:

~ assumptions inherent in the modeling approach are not valid in the region

plane strain deformation

basement deforms in manner analogous to brittle, bedded strata, that bed length and thickness are preserved

~ crustal model is not consistent with known, observed geologic and kinematic data in the region

rates and patterns of observed uplift

location and dimensions of active folds

original horizontality of mid-Cenozoic unconformity

omits several known Quaternary faults

Rates and style of deformation derived from model are not appropriate for assessing seismic hazard in contemporary tectonic setting. ~ 0

kl PACIFIC PLATE NORTH AMER(CAN PLATE

San Andreas Fault

WW/I ~ ~ ~ ~ ~ A 8

Brittle-Ductile Transition

Plate Boundary Ulhosphere

Tectonic Thlckenlng Inc!plant Subduction Uthosphere Aesthenosphere 0

JN 30'0'0'5'

~ ~ 121'0km 50'0'

30'XPLANATION

Lower hemisphere flrstmotlon plots White - Dllatlon Black —Compression

8 Dfablo Canyon Power Plant '4I + 36'30'l11'20'

~ ~ EXPLANATION 0 DloHo Canyon Pewor Ptent —~ - Poelgl doned ashore oppreclmor~ loco(ed, Inlerred, or cencoolod e

Pc- i) .A '/ Sur/ObirpoterraN~Srtinimblrrcit~

Santa Lucia Santa Lucia Hosgri Nacimiento escarpment bank fault zone fault zone Coastline

4. 4.0 r 6.0 4S LO 4.0 61 52 54 6.0 6.6 5.6 6$ 6.7 'S 5.8 r L4 6.7 7.1 5.8 8.0 20 7.1 '42 8.0 7.1 7

-120 -100 40 -20 Distance (km)

EXPLANATlON Numbers inside model ~ velocity in iun/sec ~ 4

1 30'980 - May/1988 Relocations

~ 0 0 ""4 Magnitude v,~ 00 —09 ~ 1.0 —1.9 Ej o 2.0 —2.9 0 3.0 —3.9 20'0' O~ o~ 0 ~ 0 ~ ~ ~ faulr Oyy ~ g G~ ~ ~ 4 r ~ o 35'0'21'0'0'0'0 20km Diablo Canyon Power Plant

NOTE: Base map explenet:on provided on Plate 3,

8osgri fault zone A'echo fault ~ Los Osos fault zone A B r B' 0 ~ ~ o ~ '0 ' o~gq ~ ~o 'b ~ ~ E ~ ~t 4C o o P o -10 0 -10 0 ~ 0

CL ~ ~ ~ O ~

-20 -20 v 10 20 10 20 Distance {krtt] Distance (km)

30'980 - May/1988 Relocations

o ~ 0

~ Magnitude 00 —09 1.0 —1.9 o 2.0-2.9 0 3.0 —3.9 20'0' ~ ~ ~o o ~ o 0 ~ ~ ~ ~ '' ~ ~ fg ~ . .. ( ~oe, rz ~ ~ o «0 oP ~ ~

0 20km 350 10'21'0'0'0' Diablo Canyon Power Plant

NOTE: Base map explanellon provkted on Plate 3.

Hosgri fault zone Pecho fault ~ Los Osos fault zone A As 8 r 8' Oo ~ 0 (p ~ ~ g ~ ohiog «o 'b E o ~ ~W E o ~ -10 0 -10 ~ o

C1 ~ ~ ~ O O ~

020 -20 10 20 0 10 20 Distance (km] Distance {km) I

l QUESTION GSG II

Probablllstic aaf deterministic analyrer. (ineiuding a logic tree) for thc hypothesis ofa kCad tbmt and thc'neiusion ofa ¹mson-type model in thc analysis ofthc compression ofthc'an Luis-Pismo Block should be provided.

APPROACH

~ Develop structural cross sections across San Luis/Pismo block using theories and techniques of fault-bend and fault-propagation folding

~ Incorporate all available data regarding the location and rates of Quaternary deformation

~ Identify possible seismic sources

~ Evaluate earthquake magnitude and ground motion from the modeled seismic sources

Probabihty CumuLatiee ProbabiLity c tk XJf / ~r

k GAMBRIA BLOCK cBBQ

0.0 E~~ ! X+Cy 0 10 ml

Esroro 0 15 km aay 50.0 ~4 O.B< " ~l ~gag~+ «".l~ 0.20 ase1s'+ ~ LccBe +ee ce t2t'co'.20 PIBMO BLOCK W 0.19 ~~-~W'~~+~ RANGE BLOCK Bay Fault 0.11 a4.y, r 0.13

0.15 jlj/////pg~~ //<./p/

0 Dtabto Canyon pcBtrer plat SANTA MARR VALLEYBLOCK ~ neee cene ee eneceeee ce eyncnne 0 20 0oastal upRft or subsldenco rata lnmmlyr

eo ~~olsaucaa~ ~ +<'@~a~

~/j/j/jj//j Souewrestem bourgzgy ol the ~0q.g~XQ 'an Wls/Plsmo structural block

10-'

10-4

10-'0 4„

10 7 —HosgrI Blind Thrust

10-8 .5 1 1.5 2 2.5 Spectral Acceleration 8 to 8.5 Hz (g) l't GROK'6) MOTIONS FOR POSTULATED THRUST RAMP

Peak Ir in F I a ni Mgdi~n 34th Postulated Ramp 6.1 0.39 0.67 Postulated Ramp 6.3 0.45 0.74

') A

10 ~

5.5 6 6.5 Magnitude, Nm 'E :0

all Magnitude Mw vs. Rupture Area

All Slip Types, 94 Data Points

e (P e 0 ~

Mw = 4.12 + 0.97 log(Rupture Area)

10 100 10~ 104 Rupture Area (kmZ) l LV Rupture Length (km) Rupture Width (km) Slip Rate (mm/yr)

21 0.16 0.6 0.2

Thrust Ramp 35 0.21 0.3 1.0 0.6

A''opoarephlc profile IF laura 2 t 7l

Offshore Structures Faults solid where well constrained. dashed where infened and well located; doued where inferred and approximately located

~ ~ Structurally complex xone

Onshore Structures Fault; dashed where approximately located; heavy dot where concealed but well constrained; ilaht dot where Interred

burled monocllne ~ arrow shows direction of downwarp ~jg(8~ 8g . 0 Step In bedrock, uncertain origin; bar and dot on lower side r ~ Diablo Canyon Power Plant

~ ~

~Ose

lrre ~ I \ g l~ rare ~ A 4~ ~ Olson Fault ~ ~ ~ ~ ~ San Luis Bay Fault aran Srx Lvlr

Argex ~ ~ s ~ o s s 1 \

bkm Contour Interval ~ 200 feet

Note: Base map from Plate 3 J

1 Magnitude 4. 00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 4.49I 4.99I I I I I I I Oepth 5.49 5.99 6.49 6.99 7.49 7.99 (km) 0- 0.9 3 1 0 0 0 0 0 0 1- 1.9 14 4 0 0 0 0 0 0 2- 2.9 8 4 1 0 1 0 0 0 3- 3.9 15 2 0 1 0 0 0 0 4- 4.9 23 3 1 0 0 0 0 0 5- 5.9 47 14 0 1 0 0 0 0 6- 6.9 28 ll 0 0 0 0 0 0 7- 7.9 13 5 1 2 1 0 0 0 8- 8.9 39 16 2 2 1 1 0 0 9- 9.9 14 6 0 1 0 0 0 0 10-10.9 20 8 0 1 2 0 0 0 11-11.9 13 10 2 2 0 0 0 0 12-12.9 5 4 0 2 1 1 0 0 13-13.9 7 2 1 1 0 0 0 0 14- 13 7 2 0 0 0 0 0 C E 42. 42.

Magnitude 0 6 0 7 0 6 oh 0 5 pO o 4 p pX 0 1970-1986

o 0

oO o @0 op

32. 4 'I

Jt1f 1971 1973 1966 1968 1969 1979 1980 1975 (b) San Borrego Fernando P™gu Parkfield Coyote Mtn. Coyote Lake Liverrnore Pocatello Valley 0 10 20% 0 10 20 30% 0 10 20% 0 10 20% 0 10 20'% 10 20% 0 10 2016 0 10 20 30%

see IsA e.o s.s 10 d.4 5.3 E 5.8 d. $ 15 o LU S S S Q T / T ~ N 46 dO N=48 N=143 N =298 N=65 N=111 N=62 N=500 20 A A+B

From Sibson, 1984 w\ ~ ~

~ ~ .

I ~ ~ ~

~, ' ~ « ~ ~I,I ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ . ~ &2'll'07

Los Os~

QI g~ i~o IS'oF +w'I'x

~ c+

DrW hole

D Otson '~h D Favtl +aim MI0+ 'I 2ft4F lrl'CCr fautt u O h~' ~ ~~een~ O~~ Fault

u D o

EXPLANATlQN

~ I ~ ~ Fault, dashed where foca5on is uncertain; dotted where interred by B model; U up, D down 8'.30 0.30 Map projec5on of major monoctfnaf an5cfkre axial surface; arrow Indicates dip direc5on g 0.20 E Map projec5on ot major monoclinal syncHne axial surtace; arrow Indicates dip dkec5on P 0.10 1 0.10 I Map projec5on ol major syncfine axial sur face Mode B F.f"'~~ Map projec5on of underlying fault ~~ Observed uplft rate Dkec5on ot transport on lault ramp Upliftrate predcted by Model 8 Diablo Canyon power plant dlt lee ree rr r~

vl I ~tv eeC~

Model I Aeelaed 5ecrron ffalfa Oafa Sfa faaaaf tfaf los Oeef fafaa ~ aa laa faa faataa

Affa faa

Model A l4flOnHSeCIOn Pg

j» f(' ~ QUESTION GSG 11

Ptobablllstlc and dctcrministicanaEyrcr (including a tree) tiu. a hRaf and i logic for hypothesis of tbmt thc indusion ofa Namson~ model in thc nudysis ofthc compression ofthc'an Luis-Piano Nock should bc'rovidad.

CONCLUSIONS

~ We provide a structural analysis of San Luis/Pismo block using the theories and techniques of fault-bend and fault-propagation folding.

~ Two significant problems encountered in modeling the San Luis/Pismo block:

assumptions required by the technique are not supported by geologic observations of neotectonic deformation and rheology of Franciscan Complex basement

structural solutions are non-unique because of sparse subsurface data

~ We constructed two cross-sections that span range of permissible structural solutions:

sections are end-members representing extreme styles of deformation in basement

~ sections incorporate to extent possible all observed data on Quaternary deformation

~ ~ ~ In one model, all of the deformation observed at surface is accommodated in upper 5 ~ ~ ~ ~ hlometers of crust; unlikely to be associated with earthquakes having M z 5.5.~ ~

~ In other model, postulated blind thrust ramp is assumed to be a seismic source and logic tree is developed.

~ Contribution to seismic hazard at site is not significant. pg h k

Provide the new infotmatlon which was presented at rhc meeting about thc pull-apart basin at the Sea Sbneon-Hosgn stepover.

APPROACH

~ Describe offshore structural relationship between San Simeon and Hosgri fault zones

~ Prepare structural trends map, isopach maps and structure contour maps

~ Evaluate geometry and dimensions of pull-apart basin

~ Discuss implications of basin for evaluating rates of deformation

San Simeon 35'30'22'e 120' + Bay Estero 35'30' Bay

Point

Pp San Luis

EXPLANATION ~ Diablo Canyon Power Plant +o Point Sal

Point Arguello

+ 34'30'21O *g8

,t 1

'I 9 seafloor samples of San Franciscan Complex Simeon Point San 33 seafloor samples of Simeon Monterey Formation Bay xo~ X EXPLANATION Fault, dashed where inferred, single tick on downthrown side, teeth on upthrown block of thrust fault

Axial trend of syncline

Seismic reflection line shown in zo t GSG Q1-A

Area of GSG Q12-9 and GSG Q12-10

oint tero

Estero Bay

5 km ($ a hinn 12-A March 1 Pa 7

TIME (Ioconde) TIME (seconds)

a a a a O O O ei O OI O O D 'aI

O C

Cl I Ol CV IO C CY O C o Q ~ W g Vl Q 'a It5 O Ul K IIII O Ch tee N O I- CL O O < II,I"jl

LL I CA C/7 K C9 .I 2 0CO o o 'a x E a I ~ (

I a O ~ I

a a o O O C O CV O ei

(OPUoool) ggglJ (tPllooo'I) PPg J I

TIME (aeconda) TIME (asconda) O 0 0I 0

al C 0CI O ~ v $4 'OI E

0cI ~ v v ~ \4 CI g 0,0 4o CY v'Oql C C o Q ~ H g Q c 0 cI al ce O R Vl Cv O CL z ivQ a)' 0 N A l/l

O '0 ~ v g 9 ca ~ ~ K Q C9 ~ pe ~ 6 tO 4o p g LO ql 0 K c ~La O

L J ~J z 0 0 0 0 0 2 0 Ol 0 III 0 X H (epuooea) BWIL (epuooee) gyyg h 0 7

~ k a)u

u'>D

r+ ™m D ug uD Point E

As Est~ g Bay D X.r

S2 ~ . u

$.3

D EXPUWATION ao '+s«~ Southeast pefaction ol San Skneon Iaull zone D « // —- Fault tdashed where lateral contstuity Is [ ~ '5 inleted) +4

un nv nu Boundary ol San SsneorvHosgrl l pul apart basin

Erosional truncatktn of pliocene sediments .20 —-- Two way travel time contours to base ol Pliocene sediments; contour Intervaf .10 seconds, dashed fates are supplementary contours at 0.5 seconds Intervals ~~ East fa6ng seafhor step Lif ~ Cretaceous or twassfc Franciscan Compkrx rocks al @ver geology location I

lao~ EXPLANATION D 5 U Southeast projection of San Simeon fault zone

Fault (dashed where lateral continuity is s tQ~~~ inferred)

IIII I la IIII Boundary of San SlmeonrHosgn pul.apart basin

40 ——Thickness contours ol post-Miocene deposits: contour interval 40 meters, dashed lines are supplementary ,u contours / at 20 meter intervals ~ Zero thickness ~~ East. facing seaftoor step KJf ~ Cretaceous or Jurassic Franciscan Complex rocks at diver geology location I'1

fp ! San Simeon Point

+o S.

5km

Estero EXPLANATlON Bay ~ A Fault, dashed where inferred, single tick on downthrown side

Area of seafloor bedrock outcrop

Post-late Wisconsinan sediment l thickness > 8m - ~

ll A Post-mid Pliocene 0

~,w, ) „,4'P' '.w,~C-

San Simeon . Fault Zone

B 0

:..-:.'",,;::::-:::::::."::..a ',.";:.-'.:.:'::.:."..':.'..'::::::.':-.:::..:-:.:.':.. - ':~iinS~~ Hosgri San Simeon Fault Zone Fault Zone C 0

V pl' Estero Bay i 'an Simeon F auli Zone

Hosgri Fault Zon 6 mt 8 km ~ Thickness of post-Wisconsinan sediments a 8 m gg Area of seafioor bedrock outcrop

A. Hosgri/San Simeon Stepover

Dead Sea

t> tTrrt ~ ~~ ~ fI Jordan V. Fault 'I 4rava ~ uk~ ~ Fault Arava Valley

Late Pleistocene-Holocene Dead Sea Basin Pliocene.Pleistocene Sedom Basin Miocene Hazeva Basin 0 20 km

B. Dead Sea Fault Zone (Manspeizer, 1985)

Saudi Arabia Dakar Basin

Tlran Basin Aragonese Arnona Gulf Elat Basin Basin Basin of Sinai Aqaba

0 20 km

C. Dead Sea Valley - Gulf of Aqaba (Ben-Arraham and others, 1979) '4". F

~ I

~ ll

, ~ ~ 4

* 0 Estero <. San Simeon Bay Favlt /onone

Mosgri

6 mt 8 km ~ Thickness of post-Wisconsinan sediments z 8 m gg Area of seafloor bedrock outcrop A. Hosgri/San Simeon Stepover

Hamner Pialns yi:~i'~ Buigein ~ terrace

B. Hamner Plains, Hope Fault Zone, New Zealand (Freund, 1971)

1942M rupture

1939 rupture 0 10 km

~ C.~ Niksar Pull-apart Basin, North Anatolian Fault Zone, Turkey (modified~ ~ from Hempton and Dunne, 1983) 4* lk Estero an Simeon Fault Zonone Bay/

Hosgrl Fau(ta" f Zone

8 km Thickness of post-Wisconsinan sediments > 8 m gg Area of seafioor bedrock outcrop A. Hosgri/San Simeon Stepover

Boundary of topographic basin San Andreas Fault

Gholame Southwest Valley. S anAnctr aq Fracture pRent Zone

2mi 3km

B. Cholame Valley Pull-Apart Basin - ~

~ 4* ~ r

hk 'jI '

Z',

'~ 5.

) ~ I LINE wEST Gl-3593 EAST

300 JORDAN R. 300 200 200E-m hi 100 100 0 1 rim 0

200 150 100 50

.0 ha'raaa rr ar ~YYA >nT( ~ h r« ~ ~ ~ ~ ~ Wa I a'«

~ W +rYEYahs«+' ra ~ YaarASS aa ar Q ~ Y ~

, aar'ar~ Y«aY+~«SESV, ~ ~ h ~ V arYESYS« ~ \ «~+/ * «aa«r Vr'sr' ~ Va ~ r p~rCh ~ «Aaaaaasa r 1, 1.0 O , a r~~ ~ + ..„yr ~ ~a«Y ~ . rsaavr~ ~\ aa . was' 2 ~ ~ «~a ~aa, ln m r r ~ rYEYST Era'L ««Aaan'1 " ~m ¹V'. hasar 2.0 W 2.0 ~ V r ~ )os ~ ~ «rr

~ paa ~ Aa«A ««a~ ~ ~ I/ ~ ra, r~a'S.'1 Moshoshm Rosh Pinna Saddio SSoss P 2'h¹h 200 150 100 50 0.0 '.0 ~ Yaa Y rr A ~ EY

~ w~ ~4 ~ W+hr~ W 1.0 1.0

S:v 0 g~ r ~ w r 2.0 «V. a':

From Rothstein and Bartov, 1989 0

iW (g Cj~

1 -3 mrn/yr

S San Simeon- + —y X Hosgri Stepover

s separation o overlap x ~ offset y depth (os os ~o cPyg~

~c Diablo Canyon 0 10 km

CD 0

9 PCS Table GSG Q12-A.2

ESTIMATED SLIP RATES ON SAN SIMEON AND HOSGRI FAULTZONES BASED ON GEOMETRY OF SAN SIMEON/HOSGRI PULL-APART BASIN

SLIP RATE Estimated Observed Master- Observed Basin Calculated Subsidence Rate Fault Overlap Estimated Age of Depth (assume basin Offset or (calculated from (assume overlap Sediment depth is 2 observed Basin sediment thickness ~ offset or basin Model sediment thickness) Stretching and sediment age) stretching) 5.3 Ma, 2.8 Ma 18 Ka

}t~od ears 9~80 y ~ 0.10 x (where o = 2s) y ~ 0.2& km x a 2.8 km (not applicable) a 0.53 z 1.0 (maximum post top mm/yr mm/yr y ~ basin depth of Miocene or post- x offset mid-Pliocene s = separation (spacing sediment thickness) between master faults) o overlap y a 0.012 km x 2 0.12 km z 6.7 (maximum post-late- mm/yr Wisconsinan sediment thickness)

y a 0.006 km x 2 0.08 km 8 3.3 (average post-late- mm/yr Wisconsinan sediment thickness)

x ~ 10 i 5 km 1.9 J 0.9 3.6 g 1.8 mm/yr mmlyr

Woodcock d ischer 986 subsidence ~ ~ slip y ~ 0. 28 km (not 0.28 km/5.3 Ma ~ x ~ 10 + 5 km 1.8 J 0.9 rate x rate applicable) 0.05 mm/yr mm/yr y depth y 0.28 km 0.28 km/2.8 Ma = x = IOJSkm 3.6 + 1.8 0.10 mm/yr mm/yr x ~ length of basin

SAN SIMEON/HOSGRI STEPOVER

~ Northern Termination of Hosgri Fault Zone ~ Southern Termination San Simeon Fault Zone

~ Right-Releasing Stepover ~ Active Pull-Apart

~ Theoretical and Empirical Models of Slip Rate Consistent with Transfer of Lateral Slip Between San Simeon and Hosgri l4 QUESTION GSG 12

Provide'hc new information which was presented at thc meeting about the pullwpatt basin at the See Simeon-Hosgd stepo~.

CONCLUSIONS

~ San Simeon and Hosgri fault zones are prominent, basement-involved structures that approach one another and terminate in near-offshore region between San Simeon Bay and Estero Bay.

~ Faults form en echelon right stepover 10 to 12 km long and 5 km wide.

~ Late Cenozoic subsiding basin is present in stepover region.

~ Dimensions of basin indicate that 1 to 4 mm/yr right slip is transferred across the basin. 4

vA .P;,

4 (,

J QUESTION GSG 13

Trenching on thc'an Simeon fault zone indicates that thcrc is an important strike slip component on thc Hosgri fault ofabout 1 to 9 mmlyear contributed by the San Simeon fault. acre'iny also be a contribution frtnn the P/edras Blancas zone. Provide a discussion as ro whether thcrc is such a contribution and ifso its size and sense ofslip.

APPROACH

~ Evaluate geometry and rates of deformation of Piedras Blancas antiform

~ Evaluate contribution of vertical and lateral slip from antiform to San Simeon and Hosgri fault zones. I I„

iJ EXPLANATION San Simeon Diablo Canyon Power Plant Oy Point ~ ~ ~ Fault, dotted where inferred

Axial trend of anticline or o syncline Piedras Point Blancas Estero Antiform

Point Buchon Point San Luis South Basin Compres sion al Domain~ ~ ~ ~ ~ ~ ~ ~

Point n.' Arguclio ~o

20 mi CO;. ~

~ ~ ~ ~ 30 km l yl'ag ', 6'. Point

0 5mi

0 8 km .„.,i Arroyo Del

Biancas 'll r( 0 S '% -"-"'rg V I](( Piedras Projection of Blancas San Simeon I Fault Zone

OCambria

EXPLANATION tr

~ ~ Fault, relative sense of motion shown, dashed Hosgri

Thrust fault, sawteeth on hanging wall, dashed where location not well constrained, dotted where fault does not deform late Pliocene strata

Anticlinal and synclinal fold axis, dashed where location not well constrained, dotted where structure does not deform late Pliocene strata C4 4 pp

h~* SN 0 10 km 0.0 ~If8 ~ y 'Pt~ II eP 0.0

phoae'n

1 .0 1.0

0~ Ba gpss

2.0 2.0

3.0 3.0 J-106 (Localion shown on Figure GSG Q13-2) P,

H g

t Folding 8 Flank Piedras Blanc s Antiform

0.0

-«s We O.l

a " e'g sl 0.2 ~ T f «Wi — -. 0.5 U : 04 C P A $ 045 4+e 0

~a'~ aa ~A 05 <

'C $ 0.6 C ~ ~ ~R 0.7

0.8 ",

I J' 0.9

I.O 'T . ZW

4 l.2 I I I.BI I rk. iy' o ~ ~ ~ ~ ~ LI

4 > Table GSG Q13-I

SLIP RATE ESTIMATES IN PIEDRAS BLANCAS REGION

RATE (millimeters per year)

Crustal Resolved Component Shortening

Piedras Blancas Antiform Total Normal Tangential Southwest Vergent 0.1 + 0.05 0.1 <0.05 Northeast Vergent 0.2 + 0.05 0.2 Combined 0.3 + 0.1 0.3 < 0.1

San Simeon fault zone < 0.1 1 to 3

TOTAL < 0.4 1 to3 J

Cgg QUESTION GSG 13

Trettching on the San Simeon fault zone indicates that there is an important strike slip component on the Eiosgri fault ofabout i to 3 mmlyear contributed by the San Simeon fault. 1here may abo be a contribution from the Piedras Biancas zone. Proiide a discussion ar to whether there is such a contribution and ifso irs size and sense ofslip.

CONCLUSIONS

~ Piedras Blancas antiform consists of folds and underlying thrust faults subparallel to San Simeon fault zone.

~ Crustal shortening is normal to San Simeon fault zone

shortening may result from strain partitioning or by local convergence in left- restraining bend

~ Rate of crustal shortening is < 0.3 mm/yr.

~ Resolved vertical component is < 0.3 mm/yr and tangential component to San Simeon fault zone is < 0.1 mm/yr. A

«b,

II V y

y,~ J

t , QUESTION GSG 14

Displacemenrs of2 meters per evens on thc Los Osos Jauit would suggest rupture lengths longer than those presented. Provide shc informruion used so determine rhc rupture lengths and discuss any inconsistency wish 2 meter displacemerus.

APPROACH

~ Examine the relationship between maximum displacement and rupture length for historical ruptures.

~ Assess the compatibility of 2-meter maximum displacement and rupture lengths of 19 and 36 hlometers, 1w

I. t 'lj'1

J< Esfe/O (08 /By Estero Bay OCI.( Segment 8( OC~ 4'glk to am l4y Imh Hills Segment ( C~ 0 22 Mor/0 Lopez Bav 8«in ~nr Reset voir wenM/invrr ~eertlorpllc evpfvrueh @ Luis 0.20

'I / 8/p/ BJA/I r~ ///r 0 l Segment 0.20 ~ le ..Ohon Fault 0.13 J 0.11 +"az San LrNr 0,13 005 ~F~ 'E '~~a, er 0,13 ffr; 'c/Io e( < 08 . ~ OC/r 0.15 VQ A \ O \ ~ /rc

V tp V~ err ' . v' e'.

~+p. 50.00? / C/o ~ '( +g( e(o Cg

EXPLANATION

Offshore Structures Omhore Structures

—-- ~ - Fault; solid where well comtrained, dashed —-- ~ ~ ~ ~ ~ Fault; dashed where approximately located; where Inferred snd well located, dotted heavy dot where concealed but well comtrained; where inferred end ipproximately located light dot where Inferred 5$ meter ridge Buried monocline - arrow shows direction of downwarp r.g:(g~% Structurally complex zone Step In bedrock, uncertain origin: ball on lower side 0.10 uplift rate in mm/yr derived from marine terrace investigations Inferred structural basin, may or may not be bounded by faults

Figure 2 Regional map showing segments of the Los Osos fault zone and Late Quaternary uplift rates of the San LuislPismo structural block. I It'I

1 Chapter 3 Page 3-26

Mo«vnvm Ioto> Ruptv«e Mo«imum hvcrooe Se~se Mo«imum Moonttvdc Rec«crence Rec«crcnce Moon tude Depth Lcnoth >I'S IIViCO> tcc>virtue Method Role fhstrc vt cn (sm) (em) (kmj (m) (mj

26 (0.099) 191 Rvplvre Lenoth 0.2 v O.l h (0.105) (0.7) 0.5 (0.2) Moment Rotc (0,6) C>poncnsc« 75 12 (0.595) 26 2J.. (0.5) Rvptve hrco (0.6) 0.4 v 0.2 h (04) (0.6) (0.764) 49 (O.S) (1,0) 1.5 «6 (0.5) Ret«cn Period lo. ~ ) ~cuba 0.101 (05) (10) Mo«oisplocemcnl (0.4) (0 6) ( ) ~ 5 (0.2) (0.131) (o.ios) Moment (0.5)

56 9 (0.105) 19 Rvpt«ce Leno\h 0.2 v (0.105) 44 (0.7) 0.5 (0.2) Mcmcnt Rote (0.6) E«ponenoc« 60 12 (0.411) Q6 2.1 (0.5) Ruptv«c A co (0.6) 0.4 v / {o '> (0 7) (0 77) 49 (O.S) (I 0) 1.5 «6 (tts) Relvrn Period 10,4) Chp«OC ten>tC 1>vusl (0.097) (0.5) (I.O) Mo«oisploce«nenl (Q.i) (0 6) (09) 15 57 (0 2) (o. 2s) ( (0.569) Moment (as) Notes: Values In parentheses ere probabilities h n hOrfepntel COlnppnent Of Slip rate, v n vertical component of sHp ret ~

Figure 3-6 Logic tree for Los Osos fault zone.

Diablo Canyon Power Plant yerm Seismic Pacilic Gas and Electric Company long Program \+ 103

Reverse Eqs., 15 Data Points E ~t

100

~ 0 10 ~O q4

0 0

10 1 10 Maximum DispLacement (m) ,C 103 I ~ I ~ ~ ~ I I I ~ ~ ~ ~ ~ l III I All Slip Types, 74 Dala Poinls 0 e e 0 100 0 I ~ ~ 0 ~g 0 ~ eP~~O e e ~0 10 ~O ~ 0 ~go

Ci) 0oo

I ~ ~ ~ ~ I I ~ I ~ I ~ t I ~ ~ ~

10 1 10 Narimum Displacement (m) C Maximum Displacement Regressed on Rupture Length Ru t r L n th km Maximum Di lacement m Reverse faulting 19 2.1 35 2.5

All slip types 19 35

Rupture Length Regressed on Maximum Displacement M ximum Di la ement m Ru ture Len th km Reverse faulting 29 All slip types

QUESTION GSG 14

Displacemenrs of 2 meters per event on the Los Ososfault would suggest rupture lengths longer than those presented. Provide thc information used to determine the rupture lengths and discuss any ineoasistency with 2 meter dtsplaeemetus.

CONCLUSIONS

~ Assessed maximum displacement of 2 meters and rupture lengths of 19 or 36 kilometers are compatible, based on a comparison with historical surface ruptures. *

l.~n

). ~ J 'As pe j g 'I

K I~

V QUESTION GSG 15

7he fault segmentation-rupture length presentation made at the meeting for rhe Hosgri fault "one is in question. Other segmentation points are possibie. Provide any new information pre:ented at the meeting so tha! is can be rrvirwed prior to the source charactert'evasion meeting.

APPROACH

~ Define terms related to segmentation.

~ Review bases for interpretation of segmentation points.

~ Present statistical analyses regarding validity of segmentation points. V'

I DEFINITIONS RELATED TO FAULT SEGMENTATION

Fault segmentation. The discontinuities, structural features, and fault behavioral characteristics that control the locations of coseismic rupture along fault zones. We attempt to understand fault segmentation by identifying fault segments and assessing rupture segments.

Faulr segment: A geologically coherent part of a fault zone that appears to be distinct from neighboring fault segments. Adjacent fault segments are separated by segmentation points.

Rupture segment: The part of a fault that ruptures during an individual earthquake. di gl I tp

i~ p4 5

+C' 20 mi

A ~ San Simeon/Hosgri stepover A G Point Estero ~ Norlhem termination of Hosgri fault ~ Southern termination of San Simeon fault

B ~ Los Osos fault intersection ~ 21'ingle restraining bend 4s~ QB ~ Change in seismicity q ~~~i ~ Change in veAical slip rates ~ Change in trace complexity

Diablo Canyon Power Plant C ~ Intersection of faulting bounding SW boundary of San Luis/Pismo Block ~ Change in vertical slip rates ~ Change in seismicity ~ Releasing stepover ~ Change in trace complexity ~ Change in deformation adjacent to Hosgri fault

ca Casmalia fault intersection >a/~ ~ Change in vertical slip rates ~ in seismicity Change 4q ~ Change in deformation adjacent to Hosgri fault Point Sal

E ~ Intersection of faulting bounding SW boundary of Point Sal structural b'eck "c; F ~ Purisima structure intersection Purisima Point ~ Change in seismicity ~ 17'ingle restraining bend

~ ~ g Santa Ynez River fault intersection ~,t~ 1

P t f

R C'" North Anatolian Fault

Sources: Sengor et al., 1985; Dewey et al., 1986: Barka and Kadinsky-Cade, 1988: Ambraseys and Tchalenko, 1968

1939 sr Jtt42 eb R Endpoint: south end basin and releasing step 1 Erzin n r ~t 942 Releasing double Endpoint within regional-scale ~ bend ndgap restraining single bend Restraining step to Restraining single bend parallel trace Fault branch; parallel thrust 4 1942 Restraining double bend Fault branch, releasing ~ / step lo another trace, Quaternary basin south end basin Endpoint: Fault bend Fault branch~ and basin terminus Cross fault

Change In fault zone complexity to single trace Releasing stepover Wear end Quarernary basin~ Releasing double bend~ Black Sea Fault branch

Change In complexity to numerous parallel traces Releasing double bend Fault branch and simple fault zone -(i ~ North end basin and cross fault 50 km Releasing single bend

Endpoint: S end basin, releasing stepover 1939 g I

Vg 1981 Events, Gouli Fault, Iran

Sources: Berberian and others, 1984; Nowroozi and Mohajer-Ashjai, $ 985

Endpoint: change to reverse slip; restraining double bend; regional fault bend, restraining

Fault bend, restraining

Increased trace complexity, cross and branch fault, increased strike-slip component

Restraining step and gap 0 $ 5km Releasing step, cross structures, fault branch, regional releasing step l Simplification of traces and fault )I branch, Increased dip-slip component

Releasing step and basin

Releasing stepovers 4

Restraining stepover

Minor releasing double bend

Endpoint: restraining gap and step

l f r

Endpoint: restraining gap

Increased trace complexity; basin~ Releasing step ~ Releasing double-bend and slap ~ Endpoint: releasing step, basin t ; %a,

I FAULT SEGMENTATION CIDLRACTERISTICS

(Strike-Slip and Reverse Faults)

~ Changes in recency of slip ~ Changes in sense of slip ~ Changes in slip rate ~ Changes in trace complexity ~ Changes in seismicity ~ Changes in adjacent deformation ~ Releasing and restraining double bends ~ Single bends ~ Stepovers ~ Cross faults and folds ~ Fault and fold branches ~ Gaps, discontinuities ~ Fault terminations d'g

~c,

C \

Table GSG Q15-

SEISMIC LINE Maximum'ost Maximum'ost SEISMIC L1NE Mid-P Mid-P (mm/yr) (mm/yr)

orthern eac oint Sal Reach CM-51 0.11 GSI-IOI Hosgri 0 13a W-76A 0.14 [Hosgri + Ptrrisima] [0.1+

J-113 0.10 ~204 Hosgri 0.37 San Lui PGE-I 0.32 ~GSI- 06 Hosgri 0.34 W-14 0.35 [0.37] GSI-85 0.36 [Hosgri + Purisima]

GSI-86 0.34 Southern Reach GSI-87 0.40 (0.26) GSI-112C Hosgri San Luis Ob'ea CM-119 0.21 [Hosgri + Purisima] [0.33]

J-126 0.20 GSI-115 Hosgri 6SI-97 0.21 [Hosgri + Purisima] [0.33] GSI-100 Hosgri 0.19 GSI-I 18 Hosgri [Hosgri + PurisimaJ [0.25] + Purisima] ~E-3 [Hosgri [0.34J Hosgri 0.18 Gsi-i23 Hosgri [Hosgri + PurisimaJ [0.25] [Hosgri + Purisima] [0.31]

I - Indeterminate

'Maximum value is calculated by adding a maximum coastal uplift rate east of the fault zone to the vertical slip rate based on the evaluation of the unconformity west of the fault zone.

~The presence of the unconformity on both sides of the fault zone allows for a direct measurement of the total vertical separation. r,( C

Purhlma Point s .o g 4 Oo

~ ~ 0 ~ ~ ~ Y. 0 ~ 4 ~ ~ e 0 Oe ~o 0 4~ ee o o 4 Qo IkhCHITUOES g 4 p 0.0o o I.O+ \ 8 4. o O '.0o 0 \ 0 304 O' g O .tOO4 4.0+ 10' I o 5.0+ I ,O, .",, ~'b, 41 O I Oy

O~ 50'l oO ''~ d I 2o 50'0'0'0'IO'21~ 50'0'0'0'0'20 gE

10 San SfmoorVHosgrl Stopover

Single RI~ Offshore Los Osos of Extensbn Los Fautl Osos Fautt

System of Faulting K I SW Boundary abng SW Zone of San Luis Boundary ol Phmo Sock San Luis 50 u- Phrno Sock 8

Casrnafra Fault/ Casmaka N ond of Purhfma Fault Slructuro 70 t-

n's Head Fault Uorfs Head Fautt

Purhlma Structure S end of Purhima Sbgt Stucturo fr

Santa Yner River Fault 110 Change In Changes In Fault Change In Change In Vertbaf Sy Sehnidty Intersectbns Trace ~t Rales Complexity Oebrm ation P, ~A-'

w A4

l~ LOCATIONS TRIPLETS QUADRUPLET QUINTUPLET

13 Change in seismicity Fault intersection San Simeon/Hosgri stepover

16 Change in seismicity Fault intersection 21'ingle bend

Change in vertical slip rate Los Osos fault intersection 21 single bend Change in trace complexity SW boundary zone Releasing stepover Change in adjacent deformation

47 Change in vertical slip rate Change in seismicity SW boundary zone Releasing stepover Change in trace complexity 49 SW boundary zone Releasing stepover Change in trace complexity

68 Change in vertical slip rate Casmalia fault intersection Change in trace complexity 71 Change in trace complexity Change in seismicity Change in vertical slip rate 93 Change in seismicity Purisima structure intersection 17'ingle bend

«Rounded to nearest kilometer

Table . Description of observed coinciding anomalies along the Hosgri fault zone. The location of each M-tuplet is the midpoint of the window that includes the center of each anomaly comprising the M-tuplet.

I:LPGE)GSG-Q-IS. TBL April 5, 1990 Page 1 H'&'P C

'l4

'~g

s'aC.

4 t Chapter 3 Page 3-20

20 mi

121'0'5'0'ambrla

120'30'5'30'0 Steporer Estero

km l. 45 km '" ~ .. ~ 4 -=- .:-.Puic.y ~. '110 k m

121'30' +3S~ 120'30" ''..

' ' SRlt» Y~ $ ~

Point Pe 121'0'

34'30' ~ 1 + ~ ~ ~ ~ ~ deneb'iablo ~ ~ O~

~ ~

Canyon Power Plant

Figure 3-4 Map showing rupture lengths considered for the Hosgri fault zone.

Diablo Canyon Power Plant Pacilic Gas attd Electric Company Long Term Seismic Program '" ~ ' ~ Ooooooo ~ osoos ~ o Qgj(g FQ i 1868(7) ——Calavataa-Sunul Fault

From Lindh, 1989

-1865

't Oo "~< 903,'1 903(5.8)

1955(5.5) ~ g 191 1,19'(6,2)

FQ g 1897, ~o 1979(5 8)

From LitxN, 1969

gv I l E y ElM J3 I co O / m~ CLI CO D Cy ~ O ~q gG CO LLJ CO E O OCO +~o~~+ O C'y 8 ~l U P I I I l E I 0 gV LL

CO Co

~4 e I

'l I

A. SAN JACINTO FAULT ZONE IIII Length Se ent ~km Sli Rate mm r San Bernardino Valley 50 8 + 3 San Zacinto Valley 65 11+3 Anza 50 11+3 Borrego Mountain 50 4+I Superstition 30 4+3

SAN JACINTO FAULT ZONE EARTHQUAKES

Lat Long Moment Length Slip Date ~D ~O" N-m ~oii~ ~m ~calc 1899/07/22 34.2 117.4 6.5 5.6 0.2 5.5 1923/07/23 34.1 117.3 6.2 15 0.1 6.0 1899/12/25 33.8 117.0 6.7 6.4 6.4

1918/04/21 33.8 117.0 6.8 7.0 ~ 15 50 1.2 6.8 1890/02/09 33 1/27 116 1/4 1980/02/25 33.52 116.55 5.0 1937/03/25 33.47 116.42 5.9 0.3 5.6 1969/04/28 33.34 116.35 5.8 0.5 5.8 1954/03/19 33.30 116.18 6.2 4.4 20 0.5 6.4 1892/05/28 33 1/47 116 1/47 1968/04/09 116.13 6.7 6.8 40 0.4 6.6 33.0533.19'942/10/21 116.09 6.3 40 0.4 6.6 1987/11/24 33.02 115.85 6.7 6.6 27 0.5 6.6 'A + .iP

El ' QUESTION GSG 15

~fault segtnentatlon-rupture iength presentation nuuk at thc meeting for thc Hosgri fault zone is in question. Other segmentation points arc possible. Provuk any nev ittfonttatiotcpresented at the meeting so that is can be rrvinved prior to thc source eharatsnizacion meeting.

CONCLUSIONS

~ Definitions of fault segmentation, fault segments, rupture segments.

~ Worldwide database of historical ruptures provides basis for identifying fault characteristics important to segmentation.

fault behavioral

structural

geometric

~ Segmentation points along the Hosgri fault zone are defined by multiple occurrence of important fault characteristics.

~ Statistical analysis confirms that the spatial coincidence of multiple characteristics is not due to a random process. We conclude that they occur at segmentation points along the fault zone.

~ Rupture of one or multiple fault segments leads to rupture length models for the Hosgri fault zone. e

:„$fi

i'1-

k QUESTION GSG 16

~>kgb the new itifortnatfon presented at the meeting on the southwestern boundary zone ofthe San Luis-Pismo Block.

APPROACH

~ Compile data and maps from studies along the southwestern boundary of San Luis/Pismo block

borehole data

bedrock geologic

mapping'luvial terrace mapping

analysis of detailed bathymetry

processing and analysis of near-shore geophysical data

~ Evaluate location and behavior of San Luis Bay and Olson faults

~ Evaluate hypothesis of shore-parallel fault >4

N7)

1 l ./ I R ISH HIL LS I ( I 450e .I / I Bs)d j 9) ( 660+ e>yx> ~ Gsep Ps ~6' Knob ~ 4 4 SO+10 0 j v ~ ..g 400~%

~35 Olson 36o (cc: 3po Fault ~ 660+ ! ~~80 660+ " "'+j Olson '::::,. i Hill 24k2 / «C;. esos::. r '62„ /4',:: cs 63+3.. "..'. 34O+ ';:

Wsveeut platform 2one within which the trace of the 02 f120,000 years old) 340+ 107+ Ssn Luis Bsy fault Is constrained 03 Wavewut platform l200,000 years old) 2'4k3 Hv ~ ~ 'ok1 Wsveeut > 04 12 platform I 320,000 years old) Point San Lu)s 0 1mi

0 1 km Py

k I

P, Qts gal

~ ~

Tpps Qd'< ~Op~

Qtl Qr>

C'Jf

I N70W,37NE ~ ~ 21,040+850 14C yr BP N80W,46NE KIf ~ '' ~ n "P'"''.,::. San Luis Bay Fault Tpps/KJf (2') NSOE, 43N

g,~

~;.p. East CaCO In upper 3 Original ground surface Oround surface 60 20 cm of clay seam 18 x—------Cevareff 5%,18ft 51.k' ~" ""57.4' -. 86.6'c 54 Clay sagrft fg 6.0

48 C ////// /////// I 14 0 a 42 a ul

36 10 30 0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96 102 108 Distance, feet

EXPLANATION Fault xone; arrows Indicate sense of displacement Dgc Colluvlum Marine terrace deposits. 75% rounded gravel In Fault; arrows Indicate sense of displacement fine sandy matrix. Clast predominantly Franciscan Quaternary llthologles with subordinate Pismo and Obispo Lithologic contact; solid where well constrained; Formation lithologles. dashed where approximately located Squire Member of Plsmo Formation. Gravel Tertiary Ipliocene) X 50.6'urveyed elevation In feet pattern Indicates basal part of member. IIIIllrlllllllflSoll lKlg Franciscan greenstone Cretaceous and Jurassic

Figure 9. Detailed log of the central part of the Avila Beach exposure illustrating stratigraphic relationships across the upper trace of the San Luis Bay fault. C SW

Channel margin Oeooo Sands and slits

~ ~ ~ ~~'.... =— Otganksstr =- /~ Umllsa,~~ol—( 'p~~ gg.'

. ~ ~ o ~ ~ ''::"'' ~ ' J '''...': 'Sand . " . ' I)~ r' X l~X

f ~ ~ i /, ~ of csff QQ+ /

Overview

0 ~ Oe 0 0 0 0 0+or f 0

IIXl~

'0/ ',LVQ 4 dQ~ . gWC ~ 4 jQ~% pe Sfkfo ~w/~eyw / I Fnc1te

JQfmi r ~ ~ / / / I / t ~ Detaikfd Sketch

EXPLANATION ——? Fault, dashed and queried where Qir Cobble Indistinct ge Colluvlum Contact alai Franciscan pillowed t4C sample WL-89-t collected in this greenstone zone; 2 t,040 i 850 years 8.P. a 'p

lg . a gmvI r' +$( r Q+ a ger Tmb / ~ ~ Qal . I Q n / T pgb I r 1 l r

( i p . IO ('ppe r~ ~ ~ T ~s~ q '" wl Tpp(i+~g4 — Tppt rrr TTmo CP< I; 1 l r ~... Tm.~>- Tpps g t r ~ Tml ~ I Kg g E.r/ rr gr Jpg c 'Tpp(+)~ o /

~ t Ob .... Lj''.g i s 2 I/ V Qlg l ' s / / / ~, I I I ' gP't - ~ Qm + Kg Qu/ X x~ I/I y hi/in 2 w I Lf"2 2 r-~~ I - 1 ~ "iM 3 ~ I Qi ~ .t Qu/7 ppg ) j I

2WS Tmo ~33 q'~h'l/in.'" 'l). / \

d w4 ( \ Qu Ax I 1 A'l/m \ ~~ l Kl/nt Qu r

0 lK(II 1

' II

C«

«IP

;Q Line 13

. 79, cd))~ @~at, ~+/@,. Road

0 400 feet

0 100 meters,

39 32 4

ne1 g>e 46 ".Qc M> ''. 4 46 gnr?

0 ~30 25 g J Q»>t ) 'g~ --",, 27 g>e C' I 1 / 1 j// I / / yg'/ / EXPLANATION I ] / / ck:// / O Une 16 I / / /Q l Bedrock elevation (feet) lrom C'orehole I F y/ g I / I /, / I / I -I I O26 Bedrock elevation (feet), 1989 I Q I / borehole I / / ~ ' 33 Bedrock elevation (feet) from oulcrop I

g~ Quaternary marine deposits on wave~ platform

—30———Contour (feel) on bedrock, dashed where inferred, hachured surrounding closed depression

~y Steep bedrock at range front 'contours not shown) ks Ssn Luis Bay Fault (NTSE)

LINE 15 NW 50 150 3.7 to 4.9 m step a E X Q c:'5' 47 UJ

0 0 100 DISTANCE tmews)

16 ssw 50 150 3.0 to 4.9 m step E z 25'INE Z Q Q I r str rrr 0 0 100 DISTANCE imeters)

sw LINE 37::.::: 50 150 e 2A lo 3.4 m step E X Z Q Q I r

rU UJ 0 I|III 150::::::::: 200 DISTANCE {mews)

'::.::.:: LINE 38 E 50 150 o 2.4 lo 3A m step E X X Qe Q Q " 55 C e2.5'1' llr 0 0 0 100 200 DISTANCE tmews)

EXPLANATION

Postulated lault; dip unknown; arrow ~ Quaternary marine deposit present indicates relative sense of displacement gc Quaternary colluvial deposits Borehole, elevation (in feet) of the 2trJ Quatematy sedimenVbedrock contact Ks Undifferentiated sandstone, siltstone, conglomerate and shah (Cretaceous) Marine terrace shoreline angle, elevation In feet (meters) V>

A ~ Diablo Olson Deer Irish Pecho Rattlesnake Point Canyon Hill Canyon Canyon Creek Canyon San Luis

250 210+10 Obon Fault San Luis Bay Fault Q.f orQ> T INorth trace) 200 18213 / ..... ~ 0 / Q 137+5 o 150 I 03 120f7 125%5 c / o 0013 Ct 105 21 Olson Fault 90i5 lsouth trace) 100 91 +3 ru 05+3 106ka 63i3 Se tpot5 92 7513 Q> 65g5 82g2 120ka 44~3 < 5e 50 Q 38~10 3713 +3 67+3+ 42i3 4313 5c 4013 34f5 38+3 39f3 3~ 35g3 4013 ~ .~l 27%3 % 6pa3 59+2 0....,~=- —"-~ -x~x~x~x X..~-p +fC x 2613 +25 20%3 2143 53g3 l 3 19%2 45a2 ~ 3 '" 1541 3441 3513 3535 5304g /4r R4045~ ~ Qf v 13? 35plp 35g3 23+3 2412 66ka 49ka

0 2000 feet

Horizontal scale VE 40 40x

EXPLANATION Symbols Shoreline angle ISLA) with well expressed wave.eut platform x SLA: elevation based on surveying of exposed SLA )feet; values tl foot unless otherwise shown) ——Shoreline angle ISLA) without well expressed waveeut platform 0 SLA; elevation based on drill hole projection {feat) "' "Erodedshorelinc angle ISLA) SLA: ~ lavation based on projection of surveyed bedrock exposed in seacliff or stream lfeet) + SLA: elevation based on trench logs of Hardlny and Lawson f1973) ffeet) Notes 0 SLA; elevation from 1:2000 scale topoyraphic map, 10.foot contour interval l. Error bars are shown except where symbol 5e ~ 120 ka marine terrace) is larger than error ~ Faunal assemblage sample ISubstage ~ Coral U - series date 4 Bone U -series date / Point Buchon U EXPLANATION D ——" Fault, dashed where approximately located, dotted where inactive; U = up. D = down

—Anticline, dashed where inferred

—Syncline, dashed where inferred

Geophysical line illustrated in text; number refers to geophysical survey and systemused

P 8 Fault or structural feature pick illustrated in text 2 ~ Diablo Canyon Power Plant

aul'I Ol n f D ?

San Luis Efa U U ~ ay Fault +y U D D D

Point San Luis

GEOPHYSICAL LINE

Une Survey System Figure I CM6 CDP 18 2 BBN 11 Boomer 19 U 3 CM13 CDP 18 D 4 AQT 36 Sidescan 20 5 AOT P84 Sparker. Sidescan 13. 14 5 km 6 AOT 34 Sparker 10 7 CM 119 CDP. Sidescan 9,12 8 AQT 29 Sparker 11 3 mi , l~(

J \ I 1'I' SLA ~. 9045

SLA Pp, 37+3 +e

SLA . 85+4 gc '>IO

/'c 12. to 15.toot. high X nickpoint in stream ~ I ...:.'~52.60 A' A'~ Shear zone ., ~ SLA WCP WCP 24+3 85g3'arine deposits Pa ci fi c Ocean

> .u C also .r North 'Trg~ "SLA soka ~ .::.: -'." x As shear zone: 1r .0fra ~~ SLA II. ~ .. WCP undisplaced Wcp ~ "~ gc 24t2'LA~ EXPLANATION gc '. ~st 27a3 colluvium ..~" g< Quaternary 25 3 SLA . Cretaceous sandstone lunnamedl 75.807'(f~ .''s -. wcp rocks: Cretaceous or Jurassic Franciscan Complex 28+ K/f/rrs Metavolcanic - greenstone

c/r Red chert Pa ci fi c Ocean Shoreline angle. double dot where p where offshore: dotted where Fault: dashed ~ buried concealed: teeth on upper plate: arrow ~... indicates dip direction, half arrow Indicates 35f2 SLA Shoreline angle elevation Iieet) direction and plunge of slickensldc WCP Wave cut platform elevation Ifeetl lineations; moditied from Hall and others 25t3 0 400 teat I1979I Borehole of shear zone in basement Strike and dip I.lmded bedrock outcrop /A'/A'J/mr/ x 0 100 meters Bench mark 2one within which Olson fault is constrained

Qm y I Tmm >r- / js "-.P c TA/» OM. mn ~~ ~r )gg, I CC Tmm/p

) Tmry/Tmm.~ 45, . '~-,N es -~ fg

r"p ~ 45''5 ~ M~ -a

* ~m ) Tmnt/Trm.' ram iri L ~L Tmm/Tmr. //

Diablo Canyon Power Plant rl v ~ 28 64 >) Zo~

l2 .Ssq ~26 8 .so anW

I ~ 20 1 ~g.s 8( 13 8 .Iit Olson'Fa" ts" San ~ 16 Vis ~~~I B~a @~all ~ 4 ~ 2l ~ r g64 10 .20 ~ 16 +.34 1 ~(12 .l2 I )12 lr' 4 ~ ~ ~ 4 -38 .26 36 I >'f20

56 p - -8 60 p ' x~4 Point San Luis <.22~ 20 'I '-e2 'OO ~ 2l ~ sl t

-66 .4l I 42~ ls I 26 20 ~ \ A I ~53

1 I .36 —.34 -'."'.So ~ Sl ~ 60 46 28) I -34 / /41aa

.e4 ~ 68~ ~ 59 ~ 5'2 auI ~$ 8 ~ 42

12 '0 I I 64 I gaza<> we IJ I I I ~ 74 44''r gee>

]ate 424 I I I r'12 I I I l. / ~70 ~20

I Point Buchon Q4' 1 I ~66 F4 I I <6 40' (

~ 66 0 I ~@66 -0

1 ~ 70 I

<6 ~~ ~ .20 %p .~, ).>, a%Or / \ I

~ 14 I Diablo Canyon Power Plant

116 C 26 -64 '4 'IVI ) ~ 20i

A2 ~ 26 ~7$ ~ sax I 60 > I 20t g 6

L~ IS Iii OIS( rI 76 'V I > l g54

.r"oo ..J'"Ga>~ ~azar~

See Figure Aligned with northeast-dipping I GSG Q16-22 g inactive fault exposed in sea cliff with Coincident East Trace Approximate contact between fess resistant of fault zone the Hosgri Miguelito Member lithologies to the north and more resistant Monterey Formation lithologies to the south Point Buchon S

,i(

CO — Constraints on Near CM86 23(W) Coastal Faulting SW —Reaches where faulting can be precluded 45 CQ 55 h)

E' / "'r / Point uchon / (

/ 0 2mi

0 3 km

EXPLANATION

~ ---- strandline Q 1 (80,000 years old) ~ ~ Point . Q2 strandllne (120,000 years old) San Luis ——07re strandline (>560,000 years old)

~ Qt t strandline (>1,000,000 years old) -30m- 30.meter Isobath

'jy'P/~j~ Resistant lithologies of the Monterey " and Obispo formations ~, Diablo Canyon Power Plant

QUESTION GSG 16

Provide the nnv information presented at thc meeting on thc southwestern boundary zone ofthc'cut LuLs-Pismo Block.

SUMMARY

~ Additional data are provided in Attachments A through E. Analysis of data is provided in Response.

~ Data and analyses indicate:

northeast-dipping reverse faults

0.02 to 0.12 mm/yr slip rate

~ Data and analyses provide constraints on potential locations of onshore and offshore San Luis Bay and Olson faults.

~ Data and analyses preclude existence of shore-parallel faulting. ~

'6s

) tp)1 p

5) p,.

I' QUESTION SSC 1

Provuk additional support for rhe choice of'logic tne paratneters and weights used in the seisncic source charactnizarion analyses, including a descnption ofthe soiidtatioe process of the PG&E panel Pom which the weighting ofthe wxrious source characteristics were denwd and applied in rhe program.

APPROACH

~ Reference detailed discussion of logic tree elements, weights, rationale, and support in probability theory.

~ Describe process of developing logic tree interpretations carried out by the project team. I PREVIOUS DOCUMENTATIONOF LOGIC TREES

~ Final Report, Chapter 2, 3: basis, parameters, weights

~ Question 40: basis in GSG data', uncertainty treatment

~ June 1989 GSG Meeting: GSG data

~ August, 1989 SSC Meeting: weights, sensitivity

ELICITATIONPROCESS

~ Logic tree values and probabilities developed by a consensus of the project team

~ Heavy reliance on data developed as part of LTSP

~ Evolutionary development of logic trees and progressive reduction of uncertainty (Scoping Study - Phase II/

~ Not an "expert panel," but single consensus representing range of alternatives and relative credibility

~ Technical defense of assessments, consistency checks, and documentation

~ Multiple meetings, field visits, and interactions

~ Sensitivity and implications 4N LTSP PROJECT TEAM

Dr. Clarence Allen CalTech Dr. Bruce Bolt UC Berkeley Mr. Lloyd Cluff PG&E Dr. Kevin Coppersmith Geomatrix Consultants Dr. N. Timothy Hall Earth Sciences Associates Dr. Douglas Hamilton Earth Sciences Associates Ms. Kathryn Hanson Geomatrix Consultants Dr. William Lettis Geomatrix Consultants Ms. Marcia McClaren PG&E Mr. Cole McClure Bechtel Mr. Jan Reitman Consultant Dr. William Savage PG&E Dr. Paul Somerville Woodward-Clyde Consultants Dr. Yi-Ben Tsai PG&E

SENSE OF SLIP

Strike Slip (0.65)

Hosgri Fault Oblique

Thrust (0.05)

DIP (degrees)

(0.6) Strike Slip (0.65)

70 (0.4)

90 (0.3)

,Hosgri Fault Oblique 60 (0.3) (0.6)

4S (0.1)

(OA) Thrust (0.05) (0.5) P~ Dip Sense of Slip

Strike-sUp

~ 900 Obli ue

Thrust

Strike-slip

Hosgri 60'blique

Thrust

Strike-slip

30O Oblique

Thrust I DIP. SENSE OF SLlP

Obl e 90'.48

Thrust

Strike-sl'osgri

60' Obl

70'.46

Thrust

Strike-sli

A5'.06

SLIP RATE (mm/yr)

0.5 h (0.1)

(0 4) Strike sli (0.65) 3h (0.4)

6h (0.1)

0.4 v 0.2 h (0.25)

Hosgri Fault Obli ue 0.4 v 0.4 h (0.3) (0.5)

0.2 v 0.4 h (0.25)

Thrust 0.4 v (0.05) (1.0)

10-4

10 6 —LTSP Weighting 7 Strike Slip 10 ---- Oblique Reverse/Thrust 10-8 .5 1 1.5 2 '.5 3 Spectrol Accelerotion 8 to 8.5 Hz (g)

1O-'o

1O-'O-4

10 4„

LTSP Weighting 1O-' 0.4 SS, 0.5 0, 0.1 TH

10-s .5 1 1.5 2 2.5 Spectrol Acceterotiort, 8 to 8.5 Hz (g) J

1 Chaoter 6 Page 6-7

Ground Motion Source Character&ation Characterfsatlon

l. 2. 3. 4. S. 6. 1. 8. 9. sense dip depth of length maxhnum seismicity rate of tnedtan she reduction/ of slip angle setsmogentc of fault magnitude model acttvtty attenuation ampllacatkna acne equation

Figure 6-3 Elements in logic tree used for Hosgri, Los Osos, and San Luis Bay faults.

Diablo Canyon Power Plant Pacific Gas and Electric Company tong Tenn Seismic Program 4" k

Ziv ' Chapter 6 Page 6-l

10 CJ

10 EJ X O eeoc eee,'ee eeeceo~ee cr 10+ Err ~ e ~ e< o ee ~ ~e oo eee ceo on ee ~ o ee ~ee ~a oo ee ~ e~ eee ~ ~ee ooo ee e~ ~ ~cae e+ ~ ~ ee ace ~ ~ ~ ~ o~ o eee ce ee ~ o ee ~ ~ ee o eeo ~ ee ee" o ~ e ~e

'\, ag 10'0ot0 cccee

1.00 1Z5 1o50 1.75 2.00 2Z5 250 2.75 3.00 %25 %50 3.15 4-00 Special acceleration (g) or peak ground acceleration Explanation Hosgri fault zone oooo ~ . ~ oo ~ o —~ West Huwla fault zone —————Los Osos fault zone -- Rinconada felt ~ eeeeeeeeeeeeeee San Luts + fault —Offshore Lompoc fault ~ ~-e~--~ Nacimtento fault Santa Lucia fault

Figure 6-6 Comparison of mean hazard from Hosgri fault zone to mean hazards from Los Osos and San Luis Bay faults. and to approximate mean hazards from other faults.

Diablo Canyon Power Ptant Tenn Program ~ Pacific Gas and Electric Company Long Seismic p DIABLO CANYON MEAN SEISMIC HAZARDS (HOSGRI FAULT) SENSITIVE TO SLIP TYPE

1O-'3 hl

10 ~ f4 b 1o-' hl bl C3 STRIKE SUP 1O-'O-'0 — ——. - OBLIQUE Crl —- —- - REVERSE/THRUST

7 R

1O-'.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 SPECTRAL ACCELERATION 3 TO 8.5 HZ (G) %IF' DIABLO CANYON MEAN SEISMIC HAZARDS (HOSGRI FAULT) SENSITIVITY TO ACTIVITYRATE GIVEN STRIKE-SLIP FAULT 10-i

1o-' —ACIYVITYRATE 1 ——.- ACTIVE RATE 2 —---- ACTIVI'IYRATE 3 —--- ACTIVITYRATE 4

10" 0.25 0'.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 . 2.75 3.00 .SPECTRAL ACCELERATION 3 TO 8.5 HZ (G) ~ 4

~amp DIABLO CANYON MEAN SEISMIC HAZARDS (HOSGRI FAULT) SENSITIVITY TO SEISMICITY MODEL 10"i

1o-'O-'0-~

' 1O-'0-e EXPONENTIAL ' MODEL —- CKQ&CTERISTIC MODEL

10 T

1O-'.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 .SPECTRAL ACCELERATION 3 TO 8.5 HZ (G)

g ~IS W

'tW

r DIABLO CANYON MEAN SEISMIC HAZARDS (HOSGRI FAULT) SENSITIVITY TO MA3IIMUMMAGNITUDE (ALL SLIP TYPES) 10"i

—MAX MAO=6.25 ——, - MAX NAG=6.50 —- —- — MAX MAG=6.75 ———— MAX MAG=7.00 ------MAX MAG='7.25 —--- —MAX MAG=7.50 - MAX MAG=7.75 10"I 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 . 2.75 3.00 .SPECTRAL ACCELERATION 3 TO 8.5 HZ (G) Pt3 DIABLO CANYON MEAN SEISMIC HAZARDS (HOSGRI FAULT) SENSITIVITY TO DEPTH OF SEISMOGENIC ZONE

1O-'O-'0

1O-'O-' EH - 12 KM -- —-- 15 KM fo 7

1O-'.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 SPECTRAL ACCELERATION 3 TO 8.6 HZ (G) k~'> QUESTION SSC 1

Provuk additional support for the choice of'logic tree. pmmnctcrs and weigha'sed in the snstnic source characterization analyses, including a description ofthe sollcitatiow proces ofthe PGdcE panel Pom which the weighting ofthe wvious source charactcrt'sties were ckri~ and applied in the program.

CONCLUSIONS

~ Logic tree elements and weights developed by consensus of LTSP Project Team.

~ Consensus values arrived at through data discussions, field trips, and interactions.

~ Sensitivity tests and feedbacks were undertaken to show implications of parameters and weights. II",t, + f)„

,I 4

g +pl

,p~ QUESTION SSC 2

Zhe sense ofslip PGc%E deri es for the Hosgri fault is based on evidence ofstrike-slip observed on the San Simeon fault 50 kilometers north ofthc Diablo Canyon site. Gcologie cusd gcqehyelcwf Aefe shag thc Hosgrifault appear to ofa tnore direct n4fetce ofa thrust or ~ ccu~aaV qfAfp, %is evidence includest

a. A thick upper Pliocene and Quaternary marin section west ofthe fault that isjuxtaposed against a basement surface, or a thin cover ofupper Quaternary sediment on basement, cast ofthe fault., b. Angular uneonformitles (top Miocene and mid-Pliocene) that are deformed as they approach the fault from thc west; southwest dips on thc top-Miocene unconformity range up to 40 degrees, those on the mid-Pliocene unconformity up to 20 degrees. Zhesc rclatlons indicate that thc fault has had a vertical component ofslip during thc Pliocene and probably well into the Quaternary. c. Zhc wedging~ut against the western face ofthc'osgri (or o~ its blind western branches) of unconformity-bound packets of Pliocene and younger strata. Zhe wedging, together with the deformation described abo>e, indicates a growth fault that has been actin since early Pliocene time. Moreau; it demonstrates that thc time >clues assigned to thc two uneonformities may become unreliable near thc fault and in thc block to thc northeast ofit; in these regions each unconformity represents a much grcatcr depositional or time; gap than it does to thc west, in thc ofshore Santa Maria basin. d. A warped and faulted presently sca floor and a similarly deformed late'iseonsinan (IS Ka) surface follow the same trend, and indicate the same scnsc ofvnsieal slip, as that defined by the late Plioeene- and Quaternary structures along thc Hosgri. c'. 7he broad Hosgri fault zone now separates a subsiding depositional basin on thc'outhwest from a stable or nsing wan-cut platform on thc nonheast; the prcscnt boundary and stratigraphic relations across the fault closely mimic those that prneiled during thc earlier history ofthc Hosgri.

In light ofthese faaors, justify thc Interpretation ofthc'osgrifault ar bdag pmkesiaerQ strike-st in depo.

APPROACH

~ Describe classifications of fault types

published definitions

our definition

application to Hosgri fault zone

~ Evaluate data and lines'of reasoning provided in question that indicate vertical separation

~ Provide basis for interpretation that Hosgri fault zone is strike-slip fault *I' HOSGRI FAULT ZONE

DATA SETS FOR ASSESSMENT OF SENSE OF SLIP

~ High resolution seismic

~ CDP seismic reflection

~ Bathymetry e Seismicity

~ Paleoseismic investigations e Stratigraphic correlations o Paleomagnetic ~ Quaternary investigations

~ Stress

~ Worldwide analogs p.

'h HOSGRI FAULTZONE ANALYSES TO ASSESS SENSE OF SLIP

DATA AND ANALYSES ~ Regional structural setting ~ Shallow and deep penetration seismic refiection data along entire length of fault zone ~ Quantify components of slip lateral and vertical reversals of separation inherited versus contemporary ~ Geomorphic expression linearity relief ~ Relationship to San Simeon fault zone mapping and paleoseismic studies San Simeon/Hosgri pull-apart basin: existence and transfer of slip ~ Distribution and nature of seismicity

focal mechanism s ~ DownMip geometry seismicity CDP seismic refiection data ~ Regional tectonic and kinematic data ~ Worldwide analogs geological geophysical Ig

rl HOSGRI FAULT ZONE EVIDENCE FAVORING STRIKE-SLIP DISPLACEMENT

REGI NAL STRUCTURAL ~ Aligns with known regional strike-slip faults. ~ Proposed regional stratigraphic correlations support strike-slip displacement ~ Subparailel to plate margin and San Andreas fault ~ Separates domains of contrasting regional trends. ~ Oblique to and truncates known thrust and reverse faults e Orientation of regional crustal shortening supports strike slip

HOSGRI FAULT ZONE EVIDENCE FAVORING STRIKE-SLIP DISPLACEMENT

COMPONENTS OF SLIP

~ Lateral to vertical ratio exceeds 2:1

~ Rate of lateral slip decreases north to south

~ Rate and sense of relative vertical separation varies along. trend.

~ Sense of vertical separation reverses within individual profiles. s " 4<% HOSGRI FAULT ZONE EVIDENCE FAVORING STRIKE-SLIP DISPLACEMENT

GEOMORPHIC EXPRESSION

~ Linear surface traces

~ Local southwest-facing scarps

~ Absence of prominent or subdued range front ~4

0 HOSGRI FAULT ZONE EVIDENCE FAVORING STRIKE-SLIP DISPLACEMENT

RELATIONSHIP TO SAN SIMEON FAULT ZONE

~ Related via right releasing stepover

~ High-angle strike slip fault with late Quaternary slip rate of 1 to 3 mm/yr

~ San Simeon/Hosgri stepover is active late Quaternary pull-apart which effectively transfers slip between San Simeon and Hosgri fault zones I HOSGRI FAULT ZONE EVIDENCE FAVORING STRIKE-SLIP DISPLACEMENT

SEISMICITY

~ Focal mechanism solutions near Estero Bay and San Luis/Pismo structural block indicate strike-slip on a near vertical fault to a depth of 6 km.

~ The 1980 and 1984 Point Sal earthquakes in block east of the Hosgri occurred at depths of up to 40 km, indicating a near vertical Hosgri fault to that depth. ,1

A I

~ ~ V

MAGNITUDES

0.0+ 2.0+ 3.0+ 4.0+ ay~. Yg i

y t

~r-.t~

kgl, 1

~cl

I EXPCANATION

Lower hemisphere first motion plots White —Oilation aleck —Compression

HOSG Rl RINCONADA A FAULTZONE FAULTZONE A

-10

E -20 Z TOP OCEANIC CRUST 4- -30

-40

-50 10 20 30 40 50 60 70 80 DISTANCE (km) t V RE LOCATIONS

35'

g ~ 0 o 0 0 D o 4 'i ~o 0 60'20'40'

Hosgri Casmalia A A' P tault zone ,Hfau)t zone

E 0 0 0 O oO CL ~ o o A ~ p o O -10

0 10 Distance (km) E1 HOSGRI FAULT ZONE EVIDENCE FAVORING STRIKE-SLIP DISPLACEMENT

REGlONAL STRESS FIELD AND CRUSTAL KINEMATlCS

~ P-axes from focal mechanism solutions indicate NNE-SSW maximum compression.

~ Borehole breakout stress orientations show regional northeast compression.

~ .Macrofabric analysis of late Cenozoic rocks indicate regional NNE-SSW compression

~ Faults and folds bend to the north as they approach the Hosgri fault zone.

~ NE-SW crustal shortening represented by late . Cenozoic folding and active reverse faulting east of the Hosgri fault zone requires right slip, not thrusting, on the NNW-trending Hosgri. «'W'*

'I C

~ f HOSGRI FAULT ZONE

FAVORING STRIKE-SLIP DISPLACEMENT'VIDENCE

PLATE TECTONIC MODELS ~ Kinematics of block rotation in the western Transverse Ranges require right-lateral strike-slip displacement on the Hosgri fault zone.

~ Orientation of Hosgri fault zone with respect to orientation of vector of unresolved movement between Pacific and Worth American plates. n I HOSGRI FAULT ZONE EVIDENCE FAVORING STRIKE-SLIP DISPLACEMENT

WORLDWIDE ANALOGS

~ Geological

~ Geophysical

~ Seismological

HOSGRI FAULT ZONE

~ Deformational Histo Recurrent Cenozoic displacement with associated basin formation and fold deformation Encompasses variety of Cenozoic tectonic settings resulting in complex pattern of deformation Paleogene (pre 25 ma) Possible significant (> 100 km) lateral displacement Late Oligocene to late Miocene (- 25 ma to 6 ma) Transtensional deformation Eastern margin of series of subsiding basins Late Miocene to Pliocene Transpressional deformation Significant episode of compression about 6.0 to 2.8 Ma Quaternary Displaces Post-Nisconsinan sediment Right lateral strike slip Local areas of vertical slip associated with uplifting and subsiding blocks Ã

P~1''

A'~ QUESTION SSC 2

7he sense ofsBp PGdcE deri~for thc Hosgri fault ls based on evkknce ofstnke-slip observed on the San Sinccon faalr Sct hitornetcre noah ofthe Dfahto Guoton etta treologto aaf geopltgttcal chan ahro6 the Batgrtfcnch career to ctree acorn cgrice oitcteirce a thrrat ao taratee cnapemst s . ghtc clif

a A thick upper PBocene and Quatenraty marine section west ofthc fault that fsjuxtaposed against a basement surface, or a thin corn ofupper Quaternary sedftnent on basement, east ofthc'ault.

b. Angular unconfonnitfes (top Miocene and mid-PBocene) that are deformed as they approach thc fault fiom thc west; southwest dfps on the top-Miocene unconfonnlty range up to 40 degrees, those on the mfd-PBocene unconformity up to 20 degrees. 7here relations indicate that thc fauLr har had a vatfcal * component ofsBp during thc PBocene and probably well into the Quaternary.

c. 7he wedgfngwut against the western face ofthe Hosgri (or o~ its bBnd western bnrnches) of unconformity-bound packets ofPBocene and younger strata. 7he wedging, together with described aboghe, indicates a growth fault that has been adfw since early PBocenethc'gonnatfon time. Moreover, it demonstrates that the time'aluer assignat to the two unconfonnitfes may become unreBabfe near thc fault and in the block to thc northeast ofit; in these regions each unconformity represents a much greater depositional or time, gap than ft does to thc west, ln thc onshore Santa Maria basin.

d. A warped and faulted presently sca floor and a similarly deformed fate 7Visconsinan (18 Ka) surface followthc same trend, and indicate thc same sense ofwvtfcaf sBp, as that dined by the Late PBocene and Quaternary strudures along the Hosgri.

c. 7he broad Hosgri fauLt zone now separates a subsiding depositional basin on thc southwest from a stable or rising wa~ platform on thc nonheast; thc present boundary and stratigraphic relations across the fault closely mfmfc those that prehhai fed during thc carBer history ofthe Hosgri.

Er ttght efthere factonr Jnrtlfct the btcertrretatton ofthe lgorgrtlhitt ar beTigtrccnhnatniiatgg ctrtheoltt'r ln ghatOdet'o

CONCLUSIONS

~ Although evidence of strike-slip on San Simeon fault zone is important, assessment of Hosgri fault zone is based on integrated analysis of geological, geophysical, tectonic and seismological data.

assessment includes all of the data and lines of reasoning described in Question SSC 2

~ There is no "direct" evidence of thrust or reverse faulting as indicated in the Question, only vertical separation.

~ Fault classification is based on rake of fault movement.

strike-slip faults with dips h 60 degrees have lateral to vertical slip ratio of 2:1

QUESTION SSC 2 (concluded)

~ Allof the data and lines of reasoning presented in the question are incorporated in assessment of vertical component of slip

~ Analysis of lateral to vertical rates of slip on Hosgri fault zone are 2:1 to 30:I, decreasing southward. ~ li~

S'i

T R

t QUESTION SSC 3

Pro~ a detaiied discussion ofhow and why the'erugc'isplacentens estimated for the Saa She~ fault was applied ro the Hosgrt'auLt as a maxintunt dfspiaoemarC.

APPROACH

~ Clarif'y use of average displacement estimates on the San Simeon fault for Hosgri fault. W1 t,

g lg

1 A, Chapter 3 Page 3-21

Monmum Iolol Rupbec Merimum average Sense Oeour Length Lenglh Oisokxemcnt Oisolocement Rote

20 (0.25) Rupture Long% (0.1) 45 I (0,25) 90 12 410 (0 4) (0.4) Ruptree Aeo Croonentw (O.d) (1.0) 70 No Ooto 2 rd (0.2S) (0 4) Strlc Srp (0.25) (1.0) (0.5) (I 0) folol Length Moment Rote Choroct«stc (0.65) 'IS (o.l) 110 (0.25) (1.0) (0 6) (0.4) (0 I) (0.1) Moment (aas)

20 9 110 (0.5) (0.1) (0$ ) 45 OOSOue 60 12 250 (0,5) Rupture t,englh '.4 v 0.2 h (0.5) (0.6) (0.7) (0.4) 70 No Octo No Oolo r6 (as) (0.25) Crponentor (O. I) (1.0) (1.0) (1.0) Ruptsec @co uwwH RN OA 0. ~ h/ (0 '1 110 (0.5) (I 0) (0.5) Choroc ter sic (O. I) .4 v O.d h (0.6) (tL25) 9 110 20 (0.1) (04) (0 5) Ihrusl 50 12 4S No Ooto No Ooto r6 (ac) Crponentns (0.05) (0.5) (0.6) (0.5) (0>) (10) (10) (10) Ruptcee *co Moment Role 0.4 v (0 4) (ad) (t,o) (1.0) Chef oc terislip 15 250 (02) (0.6) (02) (o.z) (0. )

Notes: Values In parentheses pro probabilities h v horizontal component of slip rpto, v ~ vortical component of slip nslo

Figure 3-5 Logic tree for Hosgri fault zone. Dtabto Canyon Power Plant Pacific Gas and Electric Company Long Term Seismic Program F

~ ''flV f6pprtt CIItlt

site ttap hut W I

Oats KnoN Crdd'k Tdllpte Ot6 W'C

~ ~ )OIIIstp pelt ters ItstIT of Sprs ttsseost fputt

~ ~ ~ ~ ~ ~ ~ ~ ~ ) ~ oo) ~ ~ ~ ~ ~ ~ ~ Trpestft Tg tlrprpfrprtrf 0 ~ Tns Attfsd ~ FBI' '~ ffpptt

TIWvtft Tl.A I'an) OaaK~c I Ims*bmttt t ' I Trprstfarr

B. 1j'P (

EXPLANATioN

Oines of equal thickness) on clayey U O.l 'sopachs ~ff)fg adfttte ~ Trace of fault exposed in trenches; dashed sandmarker horizon (unitOa); contour D where approximate, dotted where concealed; interval 0.1 ft. U up, Dsadown; arrows indicate relative direction of displacement. U Fault: U=up,p down; paired arrows indicate p relative sense of displacement. Trend of fault Orientation of fault at elevation of clayey sand marker horizon Figure 12. A. Sketch showing active strand of San Simeon fault exposed in trenches on Oak Knoll Creek fluvial terrace Qt5. B. Isopach of clayey sand marker horizon showing right lateral separation across active San Simeon fault strand. i+

i x 200 ft

Oak Knoll Creek x147.1

10 p~Tw2A ~T.3~

~Active Strand of Fault

Prominent side hill benches Tc5 Fault x233.3

EXPLANATION

U 30"wtde heckhce trench. ~ + ~ Trace of fault exposed in trenches; dashed ~ 0 where concealed where approximate, dotted or inferred; U aa up, D aa down; arrows indicc 160~ Topographic contour showing elevation relative sense of horizontal displacement. in feet; contour interval 10'.

Figure 10. Map of Oak Knoll Creek exploration site showing location of trenches.

Spring SKETCH MAFOF OEFLECTEO CHANNELOF AIRFOBtT CHEEK

9 s p t Kt c B I e Env. 4 E ~l e

Major strand of San Simeon Fault

rtrr h f U / t ~Env. 6 ~, -2 1 N.B

Airpon Env. 5 Creek

x75 7

Trough of probable tectonic origin

6 p.26

e ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

EXPLANATlON

30" wide ~~~ backhoe trench Trace of fault ex posed in trenches; dashed Env. 4 ~~ver erg ~ where approximate, dotted where concealec Backhoe trench excmatad by Bnvicom in 1977. Umup, Dmdown; arrows indicate relative sen. of horisontal displacement. OEP-26 30"-wide backhoe exploratory pit 100 feet ~5g Topographic contour showing elevation in feet; contour interval 5'. 50 meters Figure 7. Map of Airport Creek site showing location of trenches, exploratory pits and deflected channel. A w ~, i ~ . ' Surface faulting on Xianshuihe Fault Luhuo Earthquake (2/6/1973)

After Zhou et ai. 1983

Approximate epicenter 0 10 km ~ Luhuo Dandou

360

320 E 280 a CD 240 E O Cl 200 SL

120 0C N 80 O 40

E 240 200 C CD E 160 O C$ 120 CL CO 'U 80

CO 40

CD 0 0 ;"b

I' 0 0 0 In K 0 O 0 Z 0 Z IL'-

Z zLd 4J Z IA 0 N

6 ~1906 EARTHOUAKE K . SUP I-ld Lz~ lL N ~ f ~ AMOUNT OF SLIP RECOVERED SINCE 1906

400 300 200 100 0 DISTANCE FROM SAN JUAN BAUTISTA (KM) Figure 6. Slip measured on the San Aadreas fault following the great 1906 San Francisco earthquake. Solid dots show surface fault offsets; straight line segments indicate geodetic measurements of fault slip, with on~tandard-deviation error bars shown for each determination. Rectangle with diagonal hatching at bottom of graph indictes amount of slip recovered by elastic strain accumulation since 1906

The Forking Group on California Earthquake Probabilities, l988 J fp QUESTION SSC 3

Provuk a dcraikd discussion ofhow and why thc mewgc, displaccttseet estimated for thc Saa Shwee fault was applied to thc Hasgrl fault as a tnaxbttunt displacctttcnt.

CONCLUSIONS

~ Average displacement is estimated at San Simeon.

~ Maximum displacement per event not estimated, based on analogy to observed slip distributions.

~ Average displacement, through seismic moment, provides one estimate of maximum magnitude on the Hosgri fault. Other estimates come from rupture length and rupture area. wing

f>Vfl QUESTION SSC 4

1he characterization ofthe Hosgri fault as a predominantly strike-slip fault has been questioned because ofthe presence ofIow dip angle reverse faults in the zone. It ha! beet saggcttal liat aeter faults which are known to Ite strfkeeNp may have knv dip angle rnerse or thrttstftntlts am~af wkly them ln a mantter sitnlktr to that seen along the Hosgri. Ifthere is geophysical evidence for such a situation provide it. 7he San Gregorio fault in the vicinityofMonterey Bay has been mentioned as a possible candidate.

APPROACH

~ Conduct literature review of fault interpretations from seismic data

compile criteria indicative of strike-slip faulting

compile examples

~ Compare published criteria and examples to Hosgri fault zone ft CRITERIA FOR DISTINGUISHINGSTRIKFWLIP FAULTS

Summarized from Christie-Blick and Biddle (1985), Stone (1986), Zal& (1987), Withjack and others (1987), and Harding (1989):

Map Characteristics

~ Linear or curvilinear, long, laterally continuous fault zone

~ Narrow zone of highly varied structures (faults and folds) with en echelon arrangement

~ Principal displacement zone. is associated with a narrow, laterally persistent antiform or synform bounded by downward merging faults

~ Structural trends adjacent to and on either side of the principal displacement zone are incompatible

~ Principal displacement zone is associated with anomalous compressional and extensional structures at restraining and releasing bendslstepovers

Uetail ot t-nncipal displacement zone

Syttthetlc (R) shear Horsetail splay Secondaryl synthetic shear (P)

Antithetic (R'hear ~ Principal displacement zone

-'., Releasing bend

Principal displacement zone

Restraining bend

EXPLANATION

Normal-separation fault

Reverse-separation fault

Fault, arrows indicate sense of slip

Fold

Overturned fold

Areas of subsidence and sediment accumulation ~ g9

Aj .

1 CRITERIA FOR DISTINGUISHINGSTRIK~LIP FAULTS

Profile Characteristics

~ Basement separation along the principal displacement zone

~ Upward-diverging splays from the principal displacement zone, with either reverse or normal displacement

~ Thickness ofjuxtaposed sedimentary sections changes across the fault

~ Adjacent fault strands in a single profile have a different sense of vertical separation

~ The sense of vertical separation'changes along trend from profile to profile

~ The sense and magnitude of vertical separation on a fault strand changes up-section within a single profile (that is, apparent reversal in fault throw with depth)

~ Merging fault strands at depth have different apparent vertical separation

~ Change in the amount and/or direction of dip of the principal displacement zone along strike

Abrupt change in the nature of seismic facies or signature across the fault

~ Abrupt change in the style and/or intensity of deformation along the fault

~ Upward-widening zones of reflection terminations I.

'fi!

I +p

'r4 gL r MAJOR CHARACTERISTICS ~ Basement involved ~ Zone sub-vertical at depth ~ Upward-diverging and reJolnlng

splays'UXTAPOSED ROCKS ~ Contrasting rock type ~ Abrupt variations ln thickness and facies In a single stratigraphic unit

~ SEPARATION IN ONE PROFILE ~ Normal- and reverse-separation N j/ faults ln same profile ~ Variable magnitude and sense of separation for different horizons displaced by the same fault

N —Apparent normal SUCCESSIVE PROFILES R —Apparent reverse ~ Inconsistent dip on a single fault ~ Variable magnitude and sense of separation for a given horizon on single fault ~ w/%I Variable proportions of apparent 'L l normal- and reverse-separation faults / i / / ~ i Ilg \j Time-stratigraphic unit with variable gg I g tq~rl I I a /% % ~ b l~ i h I I li ~ I la, i \ /lit%. I 'l'I / +w f 'L ylang sedimentary facies i)I ~l~ g

g)i~> ~ ) ~ il~ )~)g g tl ~% Crystalline basement I ~ g Il lia~ \ Ig I ~ Principal displacement zone (From Christie-Blick and Biddle, 1985) E'/

"! >VV 0

~Q~-'B R A N C HI N 0 g.

~ ~

E ( FAULTS 2 ) Ql

CO ~ ~a aJ v Cg ((p(' h ~(4 yO r J 1 ~% 3 r ~ g ~ ~ 'a ~

~ GENTRAL 2 KM ~ STRA ~ ND

~ 1l ~ ee ~ e

- (From Harding and others, 1983)

EXPLANATlON ,L Wrench fault with normal separation; U = up, D ~down

Normal fault profile

Reverse fault profile

Crest of antkfine

correlative folds B'ossibleB-8'f —Seismic profile (Figure SSC Q4-5)

O2 —Seismic profile (Figure SSC Q4-6)

U 0

9F IS'+

Approximate. gaea shown

s'+ + 9l'ew'+ . st. U 0

+s'From

Harding and others, 1985) 4,

5> 0 SEST1 s EAST )0 0

~ >

$ ~ ill H.

Wfhl

Ch CIa 2.0

CO K

Q 4.

0 MILKS K

From Lowell, 1985 f>

CQ O'V%ST 00 8 8 EAST 10

ee Q 2.0 CO

3.0

i,o MllQ KM

5.0

From LoweN, 1985 I.

4, ( t p

.'~d'r..'„

Q 'c

'p. k

C 0.0-

~ W ~ ~" &' C

1.0- .~r

- - ~ - ~

.'L ~ ' ~f ,r I P J E -1006 ~ 3.0-

6 15,000 c, I- C5 4.0- <; ~F~+~~~~~.P~%.'~i i. v'f+ggi ii".j

~ ~

fA- J~/~ Horizontal scale 5.0-

(From Harding and oihers, 1985) F1', l3Cir, IYl F„Z

108'

P'~~z Y/g~~ 1 8 pe r /~i, Biliings (Afar DobIn and Erdmann, 1955)

North 0.0 —-— ~ ~ ~ E

V» ~ ~ /P~P " '""OEOOMOP TplTIAflY~Q. ~ a o ~ '/II~,P'ME JAAII/r~

~ ~ --'. Oa~ r . w;...-, EEE g '+ P OO ~ '4~, ~ss ~ 'W ~ ~ ' h W.H' ,o OD MEEOEOIO ~ O. PAIEOEOM E NIESOZOC - U. PNNL ~'IP,'~V. +~A ~. ~~% r ~ e ~r"' ED « I O — ~~.-~ '..'rr".'"v'i IIJIISS. - OROOVCAN ' v: ~ ~ ~ r ' ~ ~ '7 Jet ~ 4t+af ha ~V ~ ~ ~ A l 1 ~ v hr ~\ I6 BRIAN -., ~~E !

-~'un BRIAN '~~'~~„CAlN %ha ' ~ ~ ~ ~ +%I «~hVp ~

~ ~ s ~ P%NMBRIAN amyytT - ';-- ' 9 ~ 'PRECANBRIAN BASHNENT "v:,h"r.' r VhV ?- @~teal W%

"'~"".~" 2 mi ~ Oh r h "rI~ .'~ '~Vv ' ~ i 3 kill J~~r.

(From Harding and others, 1985) J

~ I * 10

J) of seismic 122415'ocation profile

122'00'21'45'anta

Cruz

3T00'onterey

correction Bay Moss Vertical exaggeration 14: Landing 36'45'ipHigh - resolution profile

go Monterey 6o~ o

36'30'0 Dip correction ,Vertical exaggeration 6:1 Intermediate - resolution Nautical miles

Section - D-D'ntermediate D resolUtion I' 0

0.5

2250

1.0 Win r //y~ 1.5 4500 1375 Seconds 3.6 km

(From Greene, 1973) *t

Cs I

i+ I San Gregorlo Fault

ld.

!- ..i. ~

Photo of seismic profile

d-D'd, .4 — ..:., ~ ':".

0.12 350 107 I

I 0.25 700 215 Seconds Feet Meters Section d-D'igh-resolution

0 1.9 km 0 1 Naical mile

(From Greene, 1973) I 122o46'8o0 Drakes Point Reyes»Y

'. Golden . Gate

10 mi 122'30'o 37 30' 10 km

0 Cy

Line S31 Q4-13 Figure SSC Seal '. Cove

Pillar Line S-29 'oint Figure SSC Q4-12

122'30'37'0'g y O

\ \ b fg(

I L 800 900 0.0

%NO ~

~ ~... ~'~r ' E ~

m EU 0

1.0 I-

800 900 0.0

PLEISTOCENE ' ' ~ I g ~ E rUPPER PLKXXNE cn 0 t5 ~ ~ &P 0 ~ ~ o ~ ~ m EO ~r O MIOCENE~. ~~ ~ 4«iA:~~~~ ~o

~ ag

coo 900 1000 0

4000 CL

8000 /

Ib" 800 900 0.0

I ~o' ' ff. w~qVe'fuff .« fV

800 0.0— PLEISTOCENE

~ UPPER PL ~ E I~

«n LU c 0 «~a'ff.~W~f wg ff'«':MIDDLE co AND LOWER MIOCENE... cb 4p '.r ~. r . ~ "i~~p "-™~

800 0

2000

4000

* C

'i Outer Salinia Santa Cruz Granitoid Basin Basement

0 0 Monterey Fan Santa Cruz High {Late Oligocene to J y I 2 s E Quaternary sediment) )V K $ 0> V yV a (ff 4 V I EU .''.(;., ~ (r, E ~ ~ ~ ~ ~ ~ ~ ' ~ O 6 ' I O r ~ Nacimiento Q. Pacific Plate .' o~ CL p Fault {?) Basement i', - r,;~~.- 8 ~ ~ San Gregorio- Tertiary Franciscan Tertiary Hosgri Fault Accretio nary San Simeon Accretionary Prism Terrane Prisim

EXPLANATION

Fault, arrows show sense of displacement

~ ~ ~ ~ ~ Top of subducfed slab

Displacement toward viewer

Displacement away from viewer

(From Saleeby, 1984) J

j'', y *

l ~ P 0402-1 HOSGRt P-0397-1 (1km N)N) PURlSlMA STRUCTURE FAULT ZONE (100m SE) WEST TRACE EAST TRA NO.4 500 450 400

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

' ~ ~ I ' i s ~ ~ I ((( ( I(((((((', < I < « <) II (((((I(( IA'I <((, 'i4((~%)$((((((4~QY@g~g+qi> >V,:,));))'( l .."„,<,,4~ I ~, ~ I < i< aa aol) aooAoooaoo

~ ~ ~ ~ Ie

"'» I» iYih%) o)(f()'o I ~ 'i(a<((l )( i(~ )))1 I I,(\ I IN ))IIII aa)l los((())g$

~ A ) I~[ttg',( ) ) I I les

'a,

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'((I ~ I . < (< s ' i ( ') o I')»)))))(I(((qq) C I(I( I,,''(gi(() ) )),)) ) I((,((I) ,. )I