1. Visualizing seismic wave propagation Peter van KekenUniversity of Michigan Jeroen Tromp Dimitri Komatitsch Caltech Shalini Venkataraman Nicholas Schwarz Luc Renambot Jason Leigh University of Illinois at Chicago American Geophysical Union, Fall 2003, ED31E-01

2. Seismology in intro geophysics University of Michigan GS420 Elastic deformation/wave equation Refraction, reflection 1D earth structure Earthquakes and seismograms Tomography Attenuation, anisotropy www.geo.lsa.umich.edu/~keken/420.html

4. From Shearer (1999)

5. PcP: average P velocity in the mantle PcP P wave shadow zone shadow zone PKIKP PKIKP: average P velocity of the Earth From Shearer (1999)

6. Ideal: Develop a good understanding of seismic wave propagation Greatly aided by improvements in: - data acquisition - computational power - computer visualization

7. Courtesy ExxonMobil Example: active source seismics

8. Examples: Global seismology Alan Jones: Seismic Waves –Seismic phases, seismograms –www.geol.binghamton.edu/faculty/joneswww.geol.binghamton.edu/faculty/jones Saadia Baker and Michael Wysession –Synthetic mantle shear waves, seismograms –Normal mode summation –http://epsc.wustl.edu/~saadia

10. 0 1 3 4 7 1217 23 Jones: seismic waves

11. Saadia and Wysession

13. New approach: SPECFEM3D Spectral finite element code (Komatitsch and Tromp, GJI, 2002; Komatitsch, Tromp and Ritsema, Science, 298, 2002 www.geoframework.org) ‘Complete’ model: allows introduction of –Ellipticity, anisotropy –3D mantle and crustal structure Massively parallel computation –Linux PC clusters at Caltech, Michigan Challenging code for visualization –Irregular grid –Massive amount of data: O(Terabyte)

15. 50s lowpass filter 14/8/95 New Britain (Mw=6.7)

16. Quiz: Name the phases labeled A through F (white/red indicate positive amplitude only) PS

17. Vanuatu, 26/11/99

18. Bolivia, 9/6/94

19. 3D = Geowall GS420 Fall 2002

20. EVL Volume Rendering Use color and transparancy (Alternative: PC based volume renderer HVR www.lcse.umn.edu) 512 3 8 bit 512 3 16 bit

21. Quiz: Name the phases labeled A through F SK PP PKP Love PPS ScPP ScSP ScSS