SCEC Award Number 10140 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Estimating Moment Accumulation Rate Distribution in Southern
Investigator(s)
Name Organization
Kaj M. Johnson Indiana University
Other Participants Ray Chuang
SCEC Priorities A3, A2, A1 SCEC Groups CDM, Geodesy, Geology
Report Due Date 02/28/2011 Date Report Submitted N/A
Project Abstract
 For the last several year we have been working on developing quasi-analytical earthquake cycle models to utilize the extensive GPS network in southern California to constrain estimates of long-term fault slip rates, the distribution of interseismic fault creep, and lithosphere viscosity
structure. In this project, we proposed
to extend this work to focus on estimating the distribution of moment accumulation rate by trying to infer where faults are locked and creeping. This goal was not entirely met for an important reason: the first-order problem in southern California is sorting out the estimates of long-term fault slip rates, not locking depths. In order to estimate the distribution of moment accumulation rate on the fault, we must know the long-term fault slip rates. We conduct a suite of inversions to examine the model dependence of fault slip rate estimates. We find that it is not possible to reconcile geologic slip rates with geodetic models using rigid block models -- some internal distortion of blocks is required.
Intellectual Merit This work will directly contribute to the goals of SCEC by addressing SCEC3 Science Priority Objectives A1,A2, and A3 which call for studies that define slip rates on southern California faults, investigate implications of geodetic/geologic rate discrepancies, and contribute to the development of a system-level deformation and stress evolution model. This research contributes directly to the goals of the WGCEP by helping to “refine estimates of observed earthquake rates and their uncertainties, both statewide and as a function of space”, and “development of deformation models that give improved slip- and stressing-rates on known faults, as well as off-fault deformation rates elsewhere”.
Broader Impacts This project helped support the research of a graduate student, Ray Chuang.
Exemplary Figure Figure 6: Strain rates and fit to data for elastic block model with parameterized block strain rates and geologic rates tightly constrained to geologic rates.