SCEC Award Number 15089 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Integrating the Rectilinear Community Fault Model with Polyviscous Block Models of Time-Dependent Interseismic Deformation
Name Organization
Brendan Meade Harvard University
Other Participants Phoebe DeVries (graduate student, Harvard)
SCEC Priorities 1e, 2b SCEC Groups Geodesy, SDOT, CS
Report Due Date 03/15/2016 Date Report Submitted 10/13/2015
Project Abstract
Viscoelastic deformation following large earthquakes in Southern California has been studied pervasive-ly (e.g., Pollitz et al., 2003; Freed et al., 2007) providing estimates of lower crustal and upper mantle rheology from these time-dependent data. As a complement to these studies, nominally steady inter-seismic GPS data have been interpreted with both tectonic and earthquake cycle models to similarly provide estimates of lower crustal and upper mantle rheology (e.g., Meade and Hager, 2005, Smith and Sandwell, 2009; Pollitz et al., 2008; Chuang and Johnson, 2011; Hearn et al., 2013). However the links between post- and interseismic deformation have been less thoroughly examined in the context of high-fidelity representations of fault system geometry in southern California (Plesch et al., 2007). Here we propose to apply the that can simultaneously explain rapid postseismic deformation following the 1992 Landers and 1999 Hector Mine earthquakes as well as the longer-term GPS velocity fields developed as the SCEC Crustal Motion Model. Our plan was to utilize a block model geometry based on the Rectilin-ear Community Fault Model and integrating the polyviscous viscoelastic code described by in our proposal from last year. The work for this coming year is focused not only code development but rather on the application of viscoelastic block models with multiple relaxation time scales to high-fidelity represen-tations of the southern California fault system. However, upon starting these calculations we determined that the required CPU time for a complete southern California model would be ~2 million core hours per run, so we pivoted, successfully!
Intellectual Merit This project extends and tests ideas related to viscoelastic stress transfer and triggering of large earth-quakes.
Broader Impacts This work supported the graduate student career of one student (Phoebe DeVries) at Harvard. As al-ways we plan to make the github repository (polyviscous earthquake cycle) public after the first set of papers is submitted.
Exemplary Figure Figure 2. Histograms of the individual times (in % of earthquake cycle) at which a maximum (positive) value of kinematically consistent Coulomb Failure Stress is reached. Thin black vertical lines represent the mean and median time of occurrence. Opacity represents recurrence earthquake cycle recurrence interval duration: the most transparent histograms (background) correspond to T = 100 years and the least transparent histograms correspond to T = 500 years.