A new algorithm for three-dimensional joint inversion of body wave and surface wave data and its application to the Southern California plate boundary region

Hongjian Fang, Haijiang Zhang, Huajian Yao, Amir Allam, Dimitri Zigone, Yehuda Ben-Zion, Clifford Thurber, & Robert D. van der Hilst

Published May 14, 2016, SCEC Contribution #6199

We introduce a new algorithm for the joint inversion of body wave and surface wave data to get better 3-D P wave (Vp) and S wave (Vs) velocity models by taking advantage of the complementary strengths of each data set. Our joint inversion algorithm takes advantage of a one-step inversion of surface
wave traveltime measurements at different periods for 3-D Vs and Vs models without constructing the
intermediate phase or group velocity maps. This allows a more straightforward modeling of surface wave traveltime data with the body wave arrival times. We take into consideration the sensitivity of surface wave data with respect to Vp in addition to its large sensitivity to Vs, which means both models are constrained by two different data types. The method is applied to determine 3-D crustal Vp and Vs models using body wave and Rayleigh wave data in the Southern California Plate Boundary Region, which has previously been studied with both double-difference tomography method using body wave arrival times and ambient noise
tomography method with Rayleigh and Love wave group velocity dispersion measurements. Our approach creates self-consistent and unique models with no prominent gaps, with Rayleigh wave data resolving shallow and large-scale features and body wave data constraining relatively deeper structures where their ray coverage is good. The velocity model from joint inversion is consistent with local geological structures and produces better fits to observed seismic waveforms than the current Southern California Earthquake Center (SCEC) model.

Key Words
Joint inversion, San Jacinto Fault Zone, seismic tomography

Citation
Fang, H., Zhang, H., Yao, H., Allam, A., Zigone, D., Ben-Zion, Y., Thurber, C., & van der Hilst, R. D. (2016). A new algorithm for three-dimensional joint inversion of body wave and surface wave data and its application to the Southern California plate boundary region. Journal of Geophysical Research: Solid Earth, 121(5), 3557-3569. doi: 10.1002/2015JB012702. http://onlinelibrary.wiley.com/doi/10.1002/2015JB012702/abstract