S eismic wave P ropagation and I maging in C omplex media: a E uropean network

1. Seismic wave Propagation and Imaging in Complex media: a European network Welcome to Kinsale! Big thanks to: Aoife, Erika, Chris,...

2. Seismic wave Propagation and Imaging in Complex media: a European network The SPICE Team • SPICE: the project • Task Groups and Highlights • The Theme: Wavefield Inversion • Outlook

3. SPICE - the facts • 2004 –2007, 6th Framework Program, Marie Curie Research Training Network • 14 Partner institutions in 10 countries • 14 PhD (3-yrs) and 14 postdoc (2-yrs) positions • Annual research and training workshops • 2004 Numerical Methods, Venice • 2005 Large scale applications, Smolenice • 2006 Inverse Problems, Kinsale • 2007 Multidisciplinary Projects, Cargese • 5 task groups • Budget 5.5 Million Euro

4. Task Groups TG • TG Small Scale • Reservoir seismics, ocean bottom wave propagation, volcano seismology • TG Local Scale • Dynamic rupture, kinematic source inversion, shaking hazard • TG Continental and Planetary Scale • Global wave propagation, tomography, imaging benchmarks • TG Numerical Methods • Novel simulation tools, code verification • TG Digital Library • Code library, Training material

5. TG Small ScaleScope VOLCANOESWave propagation in volcanic aerasModeling of volcano seismic sourcesImprovement of eruption diagnostic tools MUSHY SEAFLOORModeling of wave propagation in sea-floor mushy layersImproving interpretation of seismic observations in marine environments

6. TG Small Scale Partners: Hamburg, Naples, Zurich, Trieste, DublinScientific Progress: Development of inversion method for LP events (PS method with topography)Inversion of mushy layer seismograms

7. TG Local ScaleScope Dynamic RuptureNon-planar faultsGeneration of high frequenciesInversion for source parameters Strong Ground MotionEarthquake scenariosVisco-plastic rheologySoil-structure interactionsHighly complex structures

8. TG Local ScaleRupture on non-planar faults - Plasticity Partners: Paris, Munich, Bologna, Bratislava, Zurich, Naples, PragueScientific Progress: Kinematic source inversion: blind testKinked faultsViscoplastic behavior on faults

9. TG Local ScaleEarthquake scenarios – nonlinear rheologies Partners: Paris, Munich, Bratislava, Prague, Trieste + Milano and TrentoScientific Progress: Viscoplastic rheologiesVerification and applicationsDomain reduction methodCombined modeling of wave propagation and structural vibrations Grenoble benchmark

10. TG Planetary ScaleScope Global wave propagationForward modeling of global wave propagationReliability of global imagingImaging benchmarkNew Mantle Model European Reference ModelOrganization of workshopsData base selectionFull wave imaging

11. TG Planetary ScaleGlobal waves propagation Imaging Benchmark Partners: Paris, Bologna, Oxford, Oslo, Munich, Utrecht, Zurich + CalTech, Tokyo, Scientific Progress: Synthetic dataset for inversion Tmin=32 s, 29 events

12. TG Numerical MethodsScope Novel approachesTetrahedral meshesDiscontinuous Galerkin MethodMultidomain ChebyshevParticle methods Non-standard RheologiesViscoplasticity BenchmarksWave propagationDynamic ruptureKinematic rupture

13. TG Numerical MethodsNovel approaches to wave elastic propagation Partners: Paris, Munich, Trieste, Bratislava, Zurich, Trento, Tokyo, Potsdam Scientific Progress: viscoelastic ADER – DG and SEM on triangular gridsmuiltidomain Chebyshev in spherical geometry Hybrid FE-FD

14. TG Digital Library - Scope WWW PortalTraining materialCode libraryInteractive verificationMailing listsNewsletters Intranet Simulation dataFormatsVisualization Benchmarks

15. TG Digital LibraryThe Code Library and Benchmarks RecentProgress: Analytical solutions (e.g., bimaterial interface) www-interface for interactive waveform benchmarking Click here ...

16. Connection to other Projects CIG (US, www.geodynamics.org) Computational Infrastructure for Geodynamics (CIG) is a membership-governed organization that supports and promotes Earth science by developing and maintaining software for computational geophysics and related fields. NERIES (FP6 - Infrastructure) Network of Research Infrastructures for European Seismology: The intention of this project is to co-ordinate and improveEuropean data exchange initiatives European GRID/HPC initiatives Identifying standard seismological applications that can be run on supercomputer/GRID infrastructure -> Involvement in preparation of FP7 (supercomputing)

17. Dissemination SPICE Publications – via www pages 1st SPICE Book (Moczo et al.) -> Finite Differences 2nd SPICE Book (Brokesova) -> Ray Theory (now available)

18. The Theme: Seismic Inversion... attempting a definition ... Seismic Inversion is the process of extracting information on a physical systemby fitting theoretical predictionsof seismic observablesto observations.

19. Seismic Inverse Problems • Hypocenter location and origin time of earthquakes • 1-3D velocity models from travel times • Reflectivity from amplitudes (waveforms) • Source mechanism from P (S) polarities • Moment tensors from polarizations and amplitudes • 1-3D velocity models from surface wave phase velocities • Slip histories from waveforms • 1-3D structure from waveform X-correlations (microseismicity) • 1D structure from ambient noise measurements • (Dynamic) Fault models from seismicity • Dynamic rupture properties from waveforms • 1-3D structure from eigenmodes • Scattering properties from codas (envelopes) • Q from amplitudes (waveforms) • Particle motion or travel times for anisotropy • 1-3D structure and source from waveforms • and, and, and ...

20. Milestones ... • Woodhouse, J.H. and A.M. Dziewonski, Mapping the upper mantle: three dimensional modelling of Earth structure by inversion of seismic waveforms, J. Geophys. Res., 89: 5953-5986, 1984. • Montagner, J.-P., Seismic anisotropy of the Pacific Ocean inferred from long-period surface waves dispersion, Physics of the Earth and Planetary Interiors, vol.38, no.1, pp.28-50, 1985. • Tarantola, A., Theoretical background for the inversion of seismic waveforms, including elasticity and attenuation Pure and Applied Geophysics, vol.128, no.1-2, pp.365-399, 1988 • Peyrat, S., K.B. Olsen, and R. Madariaga (2004). Which Dynamic Rupture Parameters Can Be Estimated from Strong Ground Motion and Geodetic Data? PAGEOPH 161, 2155-2169 . • Tromp, J., C. Tape, and Q. Liu , Seismic Tomography, Adjoint Methods, Time Reversal, and Banana-Donut Kernels,, Geophysical Journal International, volume 160, Issue 1, P195-216 (2005) .

21. Milestones ... cont‘d • SambridgeM and G. Drijkoningen. Genetic algorithms in seismic waveform inversion. Geophysical Journal Inernational, 109:323--342, 1992 • Geller R.J. and T. Hara: "Two efficient algorithms for iterative linearized inversion of seismic waveform data," Geophys. J. Int., 115 (1993) 699-710. • Shapiro, N.M, M. Campillo, L. Stehly, and M.H. Ritzwoller, High-Resolution surface wave tomography from ambient seismic noise, Science, 307, 1615-1618, 2005. • Snieder, R., The theory of coda wave interferometry, Pure and Appl. Geophysics, 163,455-473, 2006 • ... and studies by Boschi, Beucler, Deuss, and many others ... .

22. Scientific programme Sunday – Monday Oral presentations of all SPICE researchers Monday – Tuesday Course on Inverse Problems Wednesday – Thursday Invited Talks, SPICE scientists, and others, oral presentations and poster session .

23. Fringe programme Tuesday 11am SPICE administrative meeting All week TG Meetings .

24. Outlook • Improving the SPICE Digital Library in quality and quantity • Cooperation with CIG, NERIES • 4th SPICE workshop in Cargese, Corsica, May 2007 • EOS Publication on SPICE code library • Special Issue on SPICE Research (e.g., PAGEOPH, PEPI, Journal of Seismology) • Coordination of SPICE Follow-up Project(s) ENJOY THE WORKSHOP!

25. Observations ... ... contain systematic and random errors ... ... need to be corrected for instrument response ... ... may have limited coverage of the target area ... Back ...

26. Seismic Observables ... ... absolute travel times ... ... differential traveltimes ... ... polarities ... ... polarizations and particle motions ... ... surface wave phase and group velocities ... ... amplitudes ... ... frequencies (spectra) ... ... envelopes (coda) ... ... static displacements ... ... rotations ... ... waveforms ... ... noise ... ... and, and, and ... Back ...

27. Theoretical predictions ... ... ray theory ... ... 1 (or 2)-D approximations (e.g., reflectivity, normal modes) ... simplified rheologies (acoustic, isotropic elastic, viscoelastic, anisotropic ...) ... scattering approximations (Born, etc. ) ... complete (numerical) solutions in 2D or 3D with limitations in frequency range ... Back ...

28. Physical system ... SOURCE ... point source ... ... finite source ... ... kinematic vs. dynamic description ... ... plane vs. irregular ... STRUCTURE ... Cartesian, spherical, arbitrary ... Topography ... ... Rheologies (acoustic, isotropic elastic, viscoelastic, anisotropic ...) ... Parameterization (cells, coefficients) RECEIVER ... Transfer function Back ...

29. Information ... What is the result of the „inversion“ ... a final model ? ... resolution, uncertainties ... ... a probability density on the model and data space! Back ...

30. Process ... ... Trial and error ... ... automatic search schemes ... ... global or local search methods ... Monte Carlo Methods (Simulated annealing, Genetic algorithms, etc.) ... gradient methods (-> adjoints) ... How many forward models do you need to calculate? Back ...