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Usarray and Other Deep Seismic Studies Of !"#$$%&'%()'*+,-$')--.'/-0/102'/+3)0-/'*4 2*(5(-(+%6'/+$32+3$-'%()'.$*2-//-/'0('+,- 7*6*$%)*'86%+-%3'%()'90*':$%()-'90; 902<'#/+-$ 8$*4-//*$'*4':-*.,&/02/ =%$+,'%()'=(>0$*(1-(+%6'"20-(2-'?-.%$+1-(+ 8#""7#@'A(/+$31-(+'7-(+-$'%()'=%$+,"2*.-'#$$%& B.-$%5*(/'C%2060+&'8DAD NMMNHS, October 25, 2009 B>-$>0-E • F-'%$-'0('%'GH*6)-('%H-I'4*$'G)0/2*>-$0(H'+,- =%$+,I'3/0(H'(-E'/-0/1*6*H02%6'01%H0(H +-2,(0J3-/D''=%$+,"2*.-'0/'+,-'.$-/-(+K)%& 23610(%5*('*4'+,0/')$0>-'+*'3()-$/+%()'+,- =%$+,D • L*32,'*('%'4-E'+,0(H/',%>-'6-%$(-)'M%()'%$- E*$<0(H'*('6-%$(0(HN'%O*3+'+,-'6%$H-K/2%6- ,0/+*$&'%()'/+$32+3$-'*4'+,-'"*3+,E-/+-$('!D"D %()'P-E'Q-R02*'E0+,'=%$+,"2*.-'%()'*+,-$ (-E')%+%D "-0/1*6*H&S''"*3$2-T'8$*.%H%5*(T'9-2-0>-$ Wavelength Compression Rarefaction Motion of Rocks Propagation Direction Source Receiver (jump) (seismometer) Motion of Rocks Excellent seismometer java applet c/o Fritz Keller: http://www.ifg.tu-clausthal.de/java/seis/sdem_app-e.html "-0/102'F%>-/'%$-'U0H,6&'"-(/05>-'+*'=6%/520+&'%() ?-(/0+&'7,%(H-/ VV!"#$%&'()!"#$%&'() VV!"*"&'()!"*"&'() VV+(),"$-.()+(),"$-.() //")%01"23-24(")%01"23-24( 5567$%867$%89924:"24:" ;%$4:2<%)=;%$4:2<%)= "%$4:>3%?"-"%$4:>3%?"- @$(,.="2#$""@$(,.="2#$"" .113A.)%'()BC.113A.)%'()BC B. Kennett http://www-crewes.geo.ucalgary.ca/Samples/ZoepExpl/ZoeppritzExplorer.html "-0/102'F%>-/'8$*.%H%+-'L,$*3H,'+,- =(5$-'=%$+,'E0+,'@0W6-'#W-(3%5*( Source (Earthquake) Recording (Seismogram) L molten The Earth is dynamic The Continents are a complex interplay of past history, new processes, and reactivated old structures The nearest plate boundary for most people is directly below their feet (the lithosphere-asthenosphere boundary 100-200 km down). The mantle “lava lamp” contains structures from continental to 10s of km-scale and couples strongly to Earth’s surface. New Scientist, 11 April, 2009 "20-(5X2'U0/+*$&'0('*3$'Y%2<&%$)Z =%$+,"2*.-'A(/+$31-(+/T'[\]^\_[ PQ'L-2,'A9A" 8#""7#@ A(/+$31-(+'7-(+-$ %()'!"#$$%&'#$$%& B.-$%5*(/'C%2060+& L$%(/.*$+%O6-'#$$%& ^_]bK^_][ ^__c'K'^_]b • [`_'/+%5*(/'/*'4%$Z'a[__'+*'H* • "+%5*('G%)*.5*(/I'0('+,-'E-/+-$('!"'%$- 2$-%5(H'%'E%<-'*4'.-$1%(-(+'-)32%5*( %()'$-/-%$2,'/+%5*(/ [ C6-R0O6-'#$$%& c 9-4-$-(2-'P-+E*$< a']__'/+%5*(/'0('2*(5H3*3/'!" • #P""'/+%5*(/ • 9-H0*(%6'(-+E*$<'/+%5*(/ • !"#$$%&'8-$1%(-(+'#$$%& ]_ • L#'/+%5*(/ D".-A(1(E.-4-2%)%18F"2-".-A(E$%A-23-.)E2A%)8 =.G"$")42-.E)%12@$(&"--.)E24"&:).>3"-/ Filtering: 10 minutes P S After Aki and Richards, 2002; Won-Young Kim, pers. commun. “Broadband” Seismogram 1 micron/s 100 - 20 s period 20 - 10 s period 2 - 0.1 s period 1 - 0.5 s period 1 - 5 Hz ? frequency 5 -10 Hz frequency d0/3%60e%5*('*4'>-$52%6'H$*3()'1*5*( 4$*1'%'6%$H-'+-6-/-0/102'-%$+,J3%<-f •Signals are dominated by surface (Rayleigh) waves. •Displacement amplitudes are 10’s of to ~100 microns. •Signals from a large earthquake anywhere in the world are easily detectible for up to many hours. c/o Chuck Ammon, PSU. "*T'E,%+')*'/-0/1*6*H0/+/'%2+3%66& 1-%/3$-'4$*1'+,-/-')%+%g • C3()%1-(+%6'1-%/3$-1-(+/'M*;-('1-%/3$-)'%/'% 43(25*('*4'.-$0*)\4$-J3-(2&ND''L,-/-'1-%/3$-1-(+/ %$-'3/-)'+*'O*+,'/+3)&'/*3$2-/'%()'$-2-0>-$/D – 8$-/-(2-'*$'%O/-(2-'*4'%$$0>%6/'MG.,%/-/IND !"#"$%&'()"*)+$%&',-./$0&%&1.%"/2 – #$$0>%6'51-/'M%O/*63+-'%()'$-6%5>-'+*'+,-'-(5$- (-+E*$<\%$$%&ND''3"./4.$,5"60$.78,/7)1$71)"2 – 8*6%$0e%5*('M*$0-(+%5*('*4'H$*3()'1*5*('0('bK)ND'3"./4.$ +&./07)0982 – #1.60+3)-'*4'H$*3()'1*5*(D''3"./4.$,+:"&1+%0&; -./$0&%&1.78,-"7+.6/;,*0$1/.&';,1&*0$1/.&';,"7$2 – 7*1.6-+-'%()')-+%06-),E%>-4*$1/'M*166,<+5"*0)4 40-"6.&'=,7>",*171)"?N H:"2I"-4"$)2JKD2.-2%2$"A%$?%01"2$"E.()2(#2"64")="=2="#($A%'()2<&(A@%$%01"24( H.0"42%)=24:"2L)="-2.)2"64")4CK22H:.-2M%-2%2A%N($2A(',%'()2#($2;%$4:D&(@"K •In much of the interior western United States, mantle upwelling has produced a heating, thinning, and stretching of the crust thousands of kilometers from the plate boundary. Plate Boundary Mantle Upwelling The Western U.S.: Intraplate Tectonics! c/o Richard Allen, UC Berkeley c/o Richard Allen, UC Berkeley =R%1.6-'9-/-%$2,S'9A"L9#'M90*':$%()-'90; "-0/102'L$%(/-2+N •A 950 km nearly great circle transect. •Pre-EarthScope •Recorded 401 earthquakes with mb ! 5.6 and 129 with mb !6.0. Research supported by NSF and Los Alamos IGPP. Logistical and equipment support from the IRIS PASSCAL Program. •RISTRA was deployed as a “seismic antenna” to scan the Earth using “teleseismic” signals from worldwide earthquakes. #(20-(+'2$3/+%6 O*3()%$0-/'%h-2+'+*)%&i/ %25>-'=%$+,'.$*2-//-/j RISTRA Receiver Function Imaging San Juan Basin Delaware Basin Moho Thick crust (42-45 km) Thinned crust (35 km), symmetric with respect Thick crust (45-50 km) to the RGR Depressed, weak Moho Sub-crustal Receiver Function Amplitude discontinuities - Proterozoic? #'6%$H-'/2%6-'>0-E'*4'+,-'"*3+,E-/+-$('!"'4$*1'9A"L9# k*3'%$-',-$-j 8,%(-$*e*02'@0+,*/.,-$- 8$*+-$*e*02'@0+,*/.,-$- 8$*+-$*e*02'@0+,*/.,-$- G"1%66K/2%6-I'Q%(+6- 2*(>-25*( Q*,*'%()'d-6*20+&'"&11-+$&'#$-'7*(/0/+-(+'E0+,'83$- ",-%$'P-2<0(H'*4'+,-'@0+,*/.,-$-'!()-$'+,-'9:9'ME-'/566 )*(i+'<(*E'+,-'4366'bK)'.02+3$-N 83$-'",-%$ ''''"01.6-'",-%$ #'2*(5(-(+'/+$-+2,-)'60<-'+%h& M*>-$'b`'10660*('&-%$/jND F06/*('-+'%6DT'^__` Example ongoing research: Earthquakes in the intermountain region – Geology in real time! ;%$4:>3%?"- .)2O"M P"6.&(QB Pioneering geophysicist H.F. Reid, fresh from his seminal study of the San Francisco earthquake, researched the Socorro earthquakes and published a paper (Reid, 1911) in the first issue of the Bulletin of the Seismological Society of America. He estimated the strongest shaking to be in the immediate Socorro area and to correspond to an acceleration of approximately 15% of gravity. InSAR image (Fialko, 2001), showing a stacked uplift space-based image using 14 radar images of the Socorro Magma Body recorded between 1992 and 2000. The vertical uplift is 2-4 mm/year. The two outlines shown are estimated Socorro magma body boundaries estimated from microearthquakes by Reinhart and Sanford (1981; solid) and Balch et al. (1998; dashed) L,-'"*2*$$*'Q%H1%'Y*)&'0/'9-/.*(/0O6-'4*$ Q32,'*4'PQi/'"-0/102'#25>0+&f 2 mm/year inflation Earthquakes in NM, 1962-present. Earthquakes near Socorro. Aster, Sanford, et al. Probabilistic ground shaking predictions for earthquake-causcd acceleration (10% probability of exceedance in 50 years), estimated for New Mexico (left; Lin and Sanford, 2000) and for the conterminous U.S. (right; U.S. Geological Survey, 1996). Estimates incorporate hazard from Holocene faults and background seismicity. Example ongoing project: RISTRA (Rio 79="L'=R.-$01-(+'MPQLT'!PQT Grande Rift Seismic Transect) !FkT'8"!T'@#P@T'fND ?%+%'2*66-25*('E066'O- 2*1.6-+-)'+,0/'P*>-1O-$j 9-/*6>0(H'2$3/+%6'+,02<(-//'%()'1%(+6-'/+$32+3$-'*4'+,-'#/.-('#(*1%6&S V`c'A9A"'8#""7#@'O$*%)O%()'/+%5*(/'M'^__[K'^__cZ'$-)'20$26-/N'2**$)0(%+-)'E0+,'+,-'al_K<1K/.%20(H !"#$$%&'/+%5*(/D VL,-'2*1.*/0+-')-.6*&1-(+',*/+/'al_'/+%5*(/'4*$'X(-K/2%6-'bK)'01%H0(H'*4'+,-'#/.-('#(*1%6&'M-1O-))-) 0('+,-'/.%$/-$'!"#$$%&')-.6*&1-(+ND VF066'.$*)32-'bK)'/-0/102'01%H-/'E0+,'$-/*635*('2*1.%$%O6-'+*'+,%+'%2,0->-)'0('+,-'.%//0>-'/*3$2- 2*1.*(-(+/'*4'+,-'^K)'9A"L9#'/+3)&D Q%(+6-'"+$32+3$-'3()-$'79="L'M%/ *4']_S__'.1'&-/+-$)%&N J. MacCarthy Example ongoing project: Analyzing Earth’s Microseism (talk this evening) Pacific Storm Swell M 8.3 Earthquake (Kuril Islands) 3600 x speed "*1-'+,0(H/'U%..-(0(H'90H,+'P*E'E0+,'=%$+,"2*.-'0('*3$'9-H0*(f •Scientists from UNM and the University of Colorado are collecting new GPS Geodesy data to see how fast the Rio Grande Rift is spreading. •New Mexico Tech/UNM/University of Wyoming students and researchers have deployed a state-of-the-art network of seismometers in Southern Colorado (from Aspen to the NM border) embedded in USArray to study the history and present-day dynamics of the Colorado Rockies and northern Rio Grande Rift (CREST). •USArray is now in our region, recording seismic activity (and providing unprecedented new data for deep seismic imaging and other science that will keep researchers occupied for at least decades). Key questions include understanding the deep 3-d structure of the Rio Grande Rift, southern Rocky Mountains, and Colorado Plateau. •A University of Texas/Baylor group is using the EarthScope FA/TA to study the “Artesia Anomaly” discovered during RISTRA, where upper mantle appears to be sinking back into the deep Earth near the edge of the Rio Grande Rift system. •Systematic large-scale 3-d mapping of the mantle by several national groups (e.g., Oregon, Berkeley, U. Colorado, …) is ongoing in the region as USArray sweeps through. so... stay tuned for new discoveries! #'4-E'X(%6'E*$)/f • We are truly in the middle of a “golden age” of Earth discovery; uncovering the detailed history and processes that affect the planet from surface to core. • Seismology provides by far the most detailed imaging of the deep Earth, and EarthScope is the most ambitious seismic imaging experiment in the history of Earth science. • The mantle is rife with fascinating structures and its processes couple strongly with the crust and our most iconic landforms.
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