Comparison of the 1960 (Mw=9.5) and the 2010 Chilean (Mw=8.8) Earthquakes. For the 2010 earthquake, within one hour………..

Ruegg et al., (PEPI, 2009)

with GPS study

“We would then conclude that the southern part of the Concepción–Constitución gap has accumulated a slip deficit that is large enough to produce a very large earthquake of about Mw= 8.0–8.5. ― Teleseismic body-wave inversion Lay et al.(GRL, 2010) Moment-rate function, Lay et al. 92010) Teleseismic body-wave inversion, Caltech Tectonic Observatory (Anthony Sladen) Slip distribution from seismic, INSAR, and GPS, courtesy of Caltech Tectonic Observatory Comparison of strain records of the 1960 (ISA) and the 2010 (PFO) Chilean earthquakes R/G sensitivity=6.3

1960 Chile

2010 Chile R2 R3 NW R4 R5 R6 nano strain

Time, s bp n 4 c 0.0005 0.01 p 1 Strain seismogram of the 2010 Chilean (Maule) earthquake recorded at PFO (NW component)

Observed R2 R3 NW R4 R5 R6 nano strain

Time, s synthetic

bp n 4 c 0.0005 0.01 p 1 2010 Chile PFO strain (observed)

G1 G2 G3 G4 EW nano-strain

NS

R1 R2 R3 R4 NW

Time, s bp_n4_c_0.0002-0.005_p1 2010 Chile PFO strain (synthetic GCMT)

G1 G2 G3 G4 EW nano-strain

NS

R1 R2 R3 R4 NW

Time, s bp_n4_c_0.0002-0.005_p1 Normal mode spectrum (from 300s to 1 hour) 2010 Maule, TUC Vertical from O.T. 20000s taper Han 0.2-0.2 computed

observed

Frequency, mHz Normal mode spectrum (from 300s to 1 hour) 2010 Maule, MAJO Vertical from O.T. 20000s taper Han 0.2-0.2 computed

observed

Frequency, mHz 1960 Chile Data 6

X5 ΔM=0.7 (empirical) 100

Tsunami amplitude in the Pacific Abe (1979, 2010)

10 Hilo

Japan_average 1960Chile, m Aleutian_average 1 California_average

0.1 0.1 1 2010 Chile, m 1960 Data 1

Tide gauge amplitude (from NGDC data base) (far-field only, i.e., exclude South America, Central America, and )

10 x10

x5

x3

x2 1960 1 x1 1960 tsunami, m tsunami, Valdivia 1960

0.1 0.1 1 2010 Maule tsunami, m

2010 Moment-rate Spectrum 1960 Chile Mw=9.5 (with ω2 reference spectra) Estimated from ISA strain Smith (1966), Mw=9.5 also tsunami Abe (1979, 2010)

2004 Sumatra Mw=9.2 9.0 Estimated from PFO strain for the 2010 event

2010 Chile Mw=8.8 8.5

Moment, N-m Moment, 8.0

Hartzell and Heaton, 1985 7.5 Also:

mB_hat= 7.6 for both 1960 Chile and 1964 Houston and Kanamori (1986)

mB_hat=7.2 for the 2004 Sumatra Kanamori( (2006)

Frequency, Hz Progress in the last 50 years

1. Long-term behavior of -zone seismicity 2. Better understanding of physics 3. Rapid response 4. Strong motion and engineering 5. Discovery of my ignorance For the 2004-Sumatra Earthquake R. Kerr (Science, 2005)

Failure to Gauge the Quake Crippled the Warning Effort

Seismologists knew within minutes that the earthquake off Sumatra must have just unleashed a tsunami, but they had no idea how huge the quake— and therefore the tsunami—really was For the 2010 Chile earthquake, within one hour……….. 2009 Is. Earthquake (Mw=8.1)

Comparison of the 1917 and 2009 Samoa earthquakes

Omori seismograms at Mizusawa 1917 Samoa Earthquake Mizusawa Omori NS, T0=38s, V=20

P S L R

10 cm

2009 Samoa, KSN Simulated Omori NS, T0=38s, V=20, h=0.2

10 cm 1917 Samoa Earthquake Mizusawa Omori EW, T0=17s, V=100

P S L R

15 cm

2009 Samoa, KSN Simulated Omori EW, T0=17s, V=100, h=0.2

30 cm C o_amp_phase E

Mizusawa 2.5

2 Rayleigh wave

1.5

Amplitude 1 Love wave

0.5

0 0 60 120 180 240 300 360 Azimuth, deg. E o_MS_global

2009 Samoa earthquake, Surface-wave magnitude, MS Mizusawa 8.5

8

S M

7.5

7 0 60 120 180 240 300 360 Azimuth, deg. 2009 Samoa

W phase solution Discrepancy between gCMT and W-phase mechanisms

CMT

P and SH waveform fits from finite-source model Radiated energy 16 ER= 4 x 10 J

Scaled energy -5 ER/Mo = 2.2 x10 ES/M0 Scaled Energy, ER/M0

M0_ES_table 0.0001

2009_Kuril 1994_Shikotan 2006_Tonga 2009 Andaman Is. 2001_India 2007_kuril

0 2009 Samoa /M R -5 2002_Sumatra

E 10

ES/M0 2003_Tokachi-oki 2008_Sumatra 2005_Nias 2007_Sumatra

2006_Kuril 2004_Sumatra-Andaman 2006_Java 2004 Sumatra-Andaman

10-6 1019 1020 1021 1022 1023

M0. N-m M0 Near-field waveforms Far-field waveforms Chen Ji’s 3-event model

A B C Mw=7.75 Mw=7.99 Mw=7.89

-15.05 -172.65 8.0 36. 20. -15.6 -172.0 8.0 51.25 16. -15.55 -172.65 16. 110. 18. 1 2 1 2 Vague evidence for a secondary event Evidence for a secondary event at close-in R1 (PPT and RAR)

200s Composite Source

What does a point source solution (e.g., gCMT and WP) mean?

Mc()() t M i t t di

ˆˆitdi Mci()() M e

ˆˆi td i t di Mci0 ()() e M e (e.g., in the LSQ sense.) new Direct sum 800s (Mw=7.81) 500s

400s 300s 200s ―Preferred‖ solution

------Mo-----strike--dip---rake----lat.-----long.---depth---centroidtime----halfduration X. 1.8e28 144 65 -86 -15.51 -172.03 18. 33 ~30 (10 s low, 20 s rise, 40 s fall) Y2. 5.4e27 185 29 90 -16.01 -172.43 18. 69 20 Z2. 5.1e27 185 29 90 -16.01 -172.43 18. 110 20

Event X origin time is USGS hypocentral time 17:48:10.85. 3-event “preferred” model

X Y Z Mw=8.10 Mw=7.75 Mw=7.73

-15.51 -172.03 18. 33 ~30 -16.01 -172.43 18. 69 20 -16.01 -172.43 18. 110 20 Direct Sum T=800s

T=500s T=200s W phase Solution 0.00167-0.005 Hz ZNE W phase solution 0.001-0.0014 Hz Chen Ji 3-event (2 normal + 1 thrust) model 0.001 to 0.0014 Hz Chen Ji 3-event (2 normal + 1 thrust) model 0.001 to 0.0014 Hz “Current” model 1 normal + 2 thrusts 0.001 to 0.0014 Hz “Current” model 1 normal + 2 thrusts 0.001 to 0.0014 Hz

Umino et al. Index of Frequency Contents Trench Axis

High Freq

Low Freq Seismograms

1 min Event 1 hp >1.0 10/10/2009 M=5.9 -15.64 -173.23 0.3 to 1.0 10 km 0.1 to 0.3

lp < 0.1

Event 2 10/19/2009 M=6.2 -15.30 -172.19 10 km Comparison of teleseismic P waveform

Event 1 Event 2 Comparison of moment-rate spectrum from teleseismic data (solid curve: ω2 spectrum) C C D D o_spec_sum_20091010 Event 1 20091010 Event 2 20091019o_spec_sum_20091019 6 106 10

5

105 10

N-m

N-m

13 13

4

4 10 moment, 10 Moment, 10 Moment, 10

1000 1000 0.01 0.1 1 0.01 0.1 1 Frequency, Hz Frequency, Hz