SCEC Award Number 14038 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title An Earthquake Simulator for UCERF3
Name Organization
Steven Ward University of California, Santa Cruz
Other Participants
SCEC Priorities 2e, 4e SCEC Groups WGCEP, EFP, Simulators
Report Due Date 03/15/2015 Date Report Submitted N/A
Project Abstract
This proposal aims to step up from the existing ALLCAL2 fault system to one that represents the UCERF3 fault system as closely as possible and to compare earthquake simulator output with UCERF3 forecasts. The basic UCERF3 deformation model consists of down dip width, strike, dip, rake, geological slip rate and surface traces of 313 fault sections. As provided, the basic UCERF3 deformation model is not suitable for earthquake simulation. Certain assumptions have to be made to adapt UCERF3 for earthquake simulation. I call my product UCERF3-ES to dif-ferentiate the two sets (ES referring to Earthquake Simulator). The current UCERF3-ES for Cal-ifornia is quite complex, including 25,586 elements in all. Progress during 2014 includes: (1) A sizable reduction in the outer loop time step and near elimination of multiple nucleations on en-try to the inner loop. This reduces the importance of fault section continuity. (2) A new approach to fixing initial section strengths based on Magnitude-Area scaling laws. (3) The first statewide rupture forecast and seismic hazard calculation based on earthquake simulation.
Intellectual Merit This project advances SCEC’s goal of moving earthquake forecasts from a largely empirical class to a more quantitative system-based approach.
Broader Impacts Rupture forecasts like UCERF3 are driven largely by the needs of society to quantify
earthquake hazards. The project utilizes the findings of UCERF3 but uses an entirely different method to reach the final product. Having two views of the same picture provides insights into the robustness of hazard estimates that society requires.

This project also funds the production of many short You Tube science videos.
To date, there have been nearly 1.5 million views of these movies.
Exemplary Figure FIGURE 5. UCERF3-ES Rupture Forecast. 30 year probability of experiencing a quake M>5.5 (left) and M>6.7 (right) per 0.1 x 0.1 degree cells. This format is identical to the recently released UCERF3 Rupture Forecast. I believe that these are the first rupture forecasts for all of California to derive from an earthquake simulator.