SCEC Award Number 11128 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Inversions for Fault Slip Rate Using Geodetic and Geologic data for UCERF3
Name Organization
William Hammond University of Nevada, Reno
Other Participants Jayne Bormann, Ph.D. student
SCEC Priorities A2, A3, C SCEC Groups CDM, Geodesy, SHRA
Report Due Date 02/29/2012 Date Report Submitted N/A
Project Abstract
We participated in a group activity where we performed inversions for California fault slip rates and off-fault strain rates using GPS and geologic data. The primary objective was to provide the Working Group of California Earthquake Probabilities (WGCEP) with a range of reasonable/agreed-­upon estimates of fault slip rates, locking/creeping distributions, and off-­fault strain rates in California that will define the “Deformation Models” for the Unified California Earthquake Rupture Forecast version 3 (UCERF3). We used our custom block modeling codes to contribute models to this exercise. The effort was coordinated by the UCERF3 GPS block modeling workshop conveners Kaj Johnson and Wayne Thatcher.
Intellectual Merit Fault slip rates are key parameters in seismic hazard models. Using geodetic data to infer fault slip rates in fault systems that are complex, such as in southern California, can be challenging. Modeling strategies and practices can have an impact of the final solution, as is shown by the fact that different participants in this group activity obtained similar but different models for slip rates, even though the velocity field and block model the used where identical.
Broader Impacts Improvements in hazard models in California will lead to better information and outcomes for people living and working on fault lines. Since geodetic data are an important input into UCERF3 model, it is necessary to evaluate the effect of modeling strategy on the final results. This exercise contributed to the understudying of the strengths and limitations of using GPS data to constrain hazard while using block models inside the existing context. This will ultimately lead to more geodetic data being used in the hazard models, and better understanding of their uncertainties.

Ph.D. student Jayne Bormann was trained and performed all of the analysis for this project and gained exposure to the SCEC community. She developed extensive experience with block modeling and an understanding of how GPS data can be used to constrain fault slip rates. Jayne will employ these skills to author two publications using block modeling before finishing her Ph.D.
Exemplary Figure Figure 4