Adjoint Tomography of the Southern California Crust
Carl Tape,1,*
Qinya Liu,2
Alessia Maggi,3
Jeroen Tromp4
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.
2 Department of Physics, University of Toronto, Ontario M5S 1A7, Canada.
3 Institut de Physique du Globe, Université de Strasbourg, 67084 Strasbourg, France.
4 Department of Geosciences and Program in Applied and Computational Mathematics, Princeton University, Princeton, NJ 08544, USA.
* To whom correspondence should be addressed. E-mail: carltape{at}gps.caltech.edu
