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Recep Cakir recepkir@dnr.wa Lingsen Meng lsmeng@caltech Michel Foundotos

Automatic determination of depth phases and earthquake focal depth using Cepstral Stacking Method (CSM) and Standing Order of Data (SOD). Recep Cakir recep.cakir@dnr.wa.gov Lingsen Meng lsmeng@caltech.edu Michel Foundotos foundoto@geoazur.unice.fr Chin-Wu Chen cwchen@ciw.edu.

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Recep Cakir recepkir@dnr.wa Lingsen Meng lsmeng@caltech Michel Foundotos

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  1. Automatic determination of depth phases and earthquake focal depth using Cepstral Stacking Method (CSM) and Standing Order of Data (SOD) RecepCakir recep.cakir@dnr.wa.gov LingsenMeng lsmeng@caltech.edu Michel Foundotos foundoto@geoazur.unice.fr Chin-Wu Chen cwchen@ciw.edu EarthScope USArray Data Processing and Analysis Short Course Student Project August 29, 2010 Northwestern University, Evanston-Chicago

  2. Objectives • Create an automatic process to detect depth phases (pP and /or sP) and determine focal depth • Report focal depth additional to ones from USGS/IRIS/CMT/regional networks • Report depth phases additional to ISC and regional network bulletins

  3. Surface of the Earth h = source depth η = slowness Earthquake Depth= h Focal Depth pP sP P Focal depth calculation Depths from pP and sP delay times h Alexander and Cakir, 2010

  4. Cepstral Method S(t)=Observed eartquake signal a and b= amplitude and polarity of delayed signals and Then or Alexander and Cakir, 2010

  5. P P wave + pP pP wave = P pP Seismic signal Time (second) pP-P delay time C1(u) Subwindow C1(t) C1(u)+ C2(u)+ C3(u) C2(t) C3(t) . . . . . . C4(t) Alexander and Cakir, 2010

  6. Cepstral Stacking Method (CSM) Stacking by summing the subwindows Stacking by multiplying the subwindows Alexander and Cakir, 2010

  7. CSM data processing workflow (in SAC) Select Total Window Length (S – P Maximum) Select Start Time (P onset) Select Subwindow Length Select Percentage Overlap Calculate Cepstrum of ith Subwindow Product and/or Sum Stack Subwindow Cepstra (i= 1, N) Pick (non-zero) Delay Time(s) of Largest Cepstral Stack Peak(s) Select Known or Assumed Crustal Velocity Model for Station Calculate Source Depth from Delay Time of First Large Peak (pP – P) Calculate Source Depth from Second Large Peak (sP – P) Assign Final Source Depth from One or Both Depth Estimates Alexander and Cakir, 2010

  8. AUTOMATIC PROCESSING Master script (Matlab) SOD Download earthquake catalog and waveform data • INITIALIZE PARAMETERS • Sub-Window Length (sec) • Percentage Overlap (%) • Stacking (product, sum, both) • Multiple Station Stacking (Y/N) • Display (all/final sub-stack plots) • Automatic Depth Estimation (Y/N) PROCESS Station k (k=1,M) STACK STATION CEPSTRA FINAL DEPTH ESTIMATE

  9. SOD recipe

  10. Matlab master script

  11. Conclusion • Rapid, automatic detection of depth phases and focal depth • Integrate programming of SOD, Matlab, and SAC Discussion • Estimation of focal mechanism • Comparison with theoretical travel time prediction • Quality control system • Array processing enhances precision

  12. References • Alexander, S.S. and Cakir, R. (2010) Further Development of the Cepstral Stacking Method (CSM) for Accurate Determinations of Focal Depths for Earthquakes and Explosions., Seismo. Res. Let., 81, 2, p356, 2010. • SOD manuals - http://www.seis.sc.edu/sod/ • Matlab manuals - http://www.mathworks.com/ • SAC manuals - http://www.iris.edu/software/sac/manual.html

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