SCEC Award Number 16093 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Surface Topography Effects in Three-Dimensional Physics-Based Deterministic Ground Motion Simulations in Southern California
Name Organization
Jacobo Bielak Carnegie Mellon University Ricardo Taborda University of Memphis Doriam Restrepo Universidad EAFIT
Other Participants Andrea RiaƱo (Ph.D. student, CMU)
SCEC Priorities 6e, 6c, 6a SCEC Groups GMSV, CME, GMP
Report Due Date 03/15/2017 Date Report Submitted 03/15/2017
Project Abstract
The main objective of this work is to estimate the extent to which realistic 3D topography plays a significant role in the seismic site response of the Oxnard plain region. Topographic features are known to be one of the causes that contribute to ground motion amplification. In principle, these amplifications occur due to the constructive interaction between incoming waves with wavelength dimensions comparable to the physical dimensions of raised topographic features. Because of their nature, these effects tend to be more influential at local scales, and particularly significant at higher frequencies. We have developed and implemented a method that allows us to perform large-scale 3D ground motion simulations incorporating explicitly the effects of surface topography in our models. Our method, called virtual topography was applied by conducting a series of simulations in a finite element parallel code part of the SCEC High-F simulation platform (Hercules), for the region of the Oxnard plain and the surrounding geologic structures. Finite element simulations with a maximum frequency of 5 Hz were performed in Hercules, the octree finite element platform developed by the Quake Group at CMU. In the study, a set of point sources scenarios were considered for the following seismic events: (1) 2009 Mw 4.4 Westlake Village earthquake, (2) 2007 Mw 4.7 Chatsworth and (3) 2003 Mw 3.6 Simi Valley earthquake. The findings exhibit significant changes as suggested by previous studies (Ma et al., 2007; Restrepo et al., 2015) and confirm the relevance of topographic effects for the Southern California region.