Impact of 3D Elastic Structure on Coseismic Green’s Functions for Static Slip Inversion

Leah Langer, Stephen Beller, & Jeroen Tromp

Published August 10, 2020, SCEC Contribution #10331, 2020 SCEC Annual Meeting Poster #127

Earthquakes often occur in regions with complex elastic structure, such as sedimentary basins and mantle wedges. However, the majority of coseismic modeling studies assume a simplified, often homogeneous elastic structure in order to expedite the modeling process and speed up calculations. These coseismic forward models are used to produce Green’s functions for finite fault inversions, so any assumptions made in the forward model may introduce bias into estimated slip models. In this study, we investigate the impact of 3D elastic structure on forward models of coseismic surface deformation. With a synthetic model of a sedimentary basin, we explore various configurations to learn which fault parameters control how much of an impact 3D structure may have on surface deformation. We find that 3D elastic structure can cause changes in the shape of surface deformation patterns. The magnitude of this effect appears to be primarily controlled by the magnitude of contrast in material properties, rather than the sharpness of contrast, the fault orientation, the location of the fault, or the slip orientation. As an example of a real-world case, we then explore the impact of 3D elastic structure with a model of the Taipei basin, Taiwan, and a simulated earthquake on the Sanchaio fault. Once again, we find that the presence of the basin leads to differences in the shape and amplitude of the surface deformation pattern. Our results imply that neglecting 3D structure may lead to bias in inferred slip models in regions with significant material heterogeneity.

Key Words
elastic heterogeneity, sedimentary basins, coseismic displacement

Citation
Langer, L., Beller, S., & Tromp, J. (2020, 08). Impact of 3D Elastic Structure on Coseismic Green’s Functions for Static Slip Inversion. Poster Presentation at 2020 SCEC Annual Meeting.

Related Projects & Working Groups
Stress and Deformation Over Time (SDOT)