Visualizing seismic wave propagation

Peter van Keken University of MichiganJeroen TrompDimitri Komatitsch CaltechShalini VenkataramanNicholas SchwarzLuc RenambotJason Leigh University of Illinois at Chicago

American Geophysical Union, Fall 2003, ED31E-01

Seismology in intro geophysicsUniversity 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

From Shearer (1999)

PcP: average P velocity in the mantle

PcP

P w

ave

shad

ow z

one

shadow zone

PKIKP

PKIKP: averageP velocity of the Earth

From Shearer (1999)

Ideal: Develop a good understanding of seismic wave propagation

Greatly aided by improvements in:- data acquisition

- computational power- computer visualization

Courtesy ExxonMobil

Example: active source seismics

Examples: Global seismology

• Alan Jones: Seismic Waves– Seismic phases, seismograms– www.geol.binghamton.edu/faculty/jones

• Saadia Baker and Michael Wysession– Synthetic mantle shear waves, seismograms– Normal mode summation– http://epsc.wustl.edu/~saadia

01347121723Jo

nes:

sei

smic

wav

es

Saa

dia

and

Wys

essi

on

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)

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

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

P S

Vanuatu, 26/11/99

Bolivia, 9/6/94

3D = GeowallGS420 Fall 2002

EVL Volume Rendering

• Use color and transparancy

(Alternative: PC based volume renderer HVR www.lcse.umn.edu)

5123 8 bit 5123 16 bit

Quiz: Name the phases labeled A through F

SK

PP

PKP

Love

PPS

ScPP

ScSP ScSS