A 3D Finite Element Model to Investigate Elastic Heterogeneity and Topography Effects on 2010 Mw 7.2 El-Mayor Cucapah Earthquake Coseismic Deformation Using Space Geodetic Data

Date: 4/25/2019

Time: 08:45 AM

Room: Puget Sound

The 4 April 2010 Mw 7.2 El Mayor-Cucapah (EMC) earthquake, provides a good opportunity to investigate the complex dynamic processes of transform plate boundary, where the response of the lithosphere to seismic events is influenced by the interaction among multiple faults, lithospheric heterogeneities, and topographic effects. Most of existing studies represent the EMC area as an elastic half-space or layered structure or assume overly simplified fault configurations, which leads to considerable variability in resultant fault slip models. To investigate the effects of fault geometry, surface topography and elastic heterogeneities, we developed a sophisticated realistic 3D finite element model that includes multiple faults, a digital elevation model and material heterogeneities obtained from seismic tomography studies. We first performed a series of benchmark tests to validate the model performance against analytical solution. We then run realistic forward models to assess the goodness of one of the most recent published fault slip distribution, by comparing the surface displacements predicted from our models with observations. Several comparisons were made to investigate the effects of topography and material heterogeneities on the surface displacement field computed numerically. Finally, in order to improve the chosen fault slip distribution, we performed a series of inverse models using the optimization code SNOPT. Available surface geodetic deformation data (GPS and InSAR) were used to find a new slip distribution capable to produce surface displacements that provide better fits to the observations. Checkerboard tests with synthetic datasets were used to quantify the resolution of our results.

Presenting Author: Fabio Pulvirenti

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