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Group B, Poster #230, Ground Motions

3D Deterministic Ground Motion Simulations up to 5Hz: Calibration, Validation, and Application of a Seismic Velocity Model in Peru-Chile Coastal Regions

Ke Xu, Daniel Roten, & Kim B. Olsen
Poster Image: 

Poster Presentation

2022 SCEC Annual Meeting, Poster #230, SCEC Contribution #12316 VIEW PDF
Given the high seismic activity and risk of earthquake damage in the Peru-Chile coastal regions along the South American subduction zone, it is crucial to properly estimate the level of ground motions expected for future megathrust events. In this study, we have applied deterministic wave propagation simulations to calibrate and validate a 3D Community Velocity Model (CVM) for central and southern Chile. The CVM is based on the Lawrence Livermore National Lab Global 3D seismic tomography background model (Simmons et al., 2019) to a depth of 160 km. In addition, we have incorporated more detailed features into the model, including the SLAB 2.0 subduction zone geometry model (Hayes et al., 201...8), ambient noise tomography across the central Andes (Ward et al., 2013) and the Santiago de Chile basin model with a modified sediment-bedrock interface (Pilz et al., 2011). Finally, we have incorporated 1D borehole data from the Concepcion and Vina del Mar areas into the CVM, and introduced bathymetry data from GEBCO-2019 and a geotechnical layer derived from topography following Ely et al. (2010).

We have validated the CVM using deterministic wave propagation simulations of the 2010 Mw8.8 Maule, Chile, earthquake, carried out with the discontinuous mesh finite difference code AWP-ODC up to 5 Hz. Our source model consists of a smooth background slip distribution with superimposed, optimally located high stress-drop subevents (Frankel, 2016), which provides satisfactory fit of the synthetics to strong motion data and ground motion prediction equations (GMPEs). Furthermore, using the validated CVM, we have designed scenario simulations for megathrust scenario events with magnitude up to Mw9.5, relevant for risk assessment of densely-populated urban areas around Lima-Callao, Santiago, Viña del Mar, and Concepción.