SCEC Award Number 06028 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Continued analysis of spatio-temporal strain patterns associated with southern California earthquakes
Name Organization
Thorsten Becker University of Southern California
Other Participants Iain Bailey (Graduate student)
Yehuda Ben-Zion (USC faculty)
SCEC Priorities SCEC Groups Seismology, FARM, Fault Systems
Report Due Date N/A Date Report Submitted N/A
Project Abstract
Funding is requested to continue an analysis of spatio-temporal (4-D) strain patterns based on seismicity, with a focus on small-scale features associated with the numerous low-magnitude events. We sum focalmechanism derived potencies to establish a database of seismic strain release and, importantly, its uncertainties in the broadest sense. Existing datasets are evaluated, and we also derive our own seismicity catalogs for comparative analysis. We find discrepancies between the different datasets but have not yet fully quantified
the complicating relationships between large-scale strain accumulation and multi-scale patterns of strain release. Other issues arise due to the differences between summations based on large-number, low-quality vs.
low-number, high-quality focal mechanisms. Continued study will examine seismotectonic strain patterns on a range of scales and their relationship to fault geometry and mechanics. In particular, we will focus on the question of homogeneity or complexity of small-event strain release in relationship to geometrical features of faults and previous large earthquake ruptures. Important aspects of this are an effort to detect potential changes in the strain patterns associated with faults at different evolutionary stages, and an effort
to understand how large scale, regional patterns emerge from smaller scale features. These targets overlap with SCEC science goals, including the investigation of methods for using CMM/SCIGN/EarthScope products to estimate spatial and temporal variations in deformation rate, and compare these with related observations over different time scales. The expected findings may have significant implications for stress triggering calculations, fault mechanics, and modeling of crustal deformation.