Adjoint tomography of the southern California crust

Carl H. Tape

Published 2009, SCEC Contribution #1261

Using an inversion strategy based on adjoint methods, we developed a three-dimensional seismological model of the southern California crust. The resulting model involved 16 tomographic iterations, which required 6800 wavefield simulations and a total of 0.8 million central processing unit hours. The new crustal model reveals strong heterogeneity, including local changes of +/- 30% with respect to the initial three-dimensional model provided by the Southern California Earthquake Center. The model illuminates shallow features such as sedimentary basins and
compositional contrasts across faults. It also reveals crustal features at depth that aid in the tectonic reconstruction of southern California, such as subduction-captured oceanic crustal fragments. The new model enables more realistic and accurate assessments of seismic hazard.

Key Words
United States, tomography, sedimentary basins, data processing, elastic waves, California, shallow depth, digital simulation, seismic risk, basins, heterogeneity, faults, seismograms, seismic profiles, three-component seismographs, numerical models, iterative methods, three-dimensional models, inverse problem, seismographs, wave fields, plate tectonics, Southern California, velocity structure, traveltime, synthetic seismograms, geophysical profiles, earthquakes, crust

Citation
Tape, C. H. (2009). Adjoint tomography of the southern California crust. Science, 325, 988-992.