SCEC Award Number 16273 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Continued Development of OpenSHA/UCERF3 in Support of Operational Earthquake Forecasting, Hazard Assessment, and Loss Modeling
Investigator(s)
Name Organization
Thomas Jordan University of Southern California Edward Field United States Geological Survey Kevin Milner University of Southern California
Other Participants
SCEC Priorities 2b, 2e, 4e SCEC Groups CS, WGCEP, EFP
Report Due Date 03/15/2017 Date Report Submitted 06/30/2017
Project Abstract
 Major developments were made in support of Operational Earthquake Forecasting (OEF). Development was primarily focused on the UCERF3-ETAS model which was published in February 2017 (BSSA). This model bridges the gap between point process spatiotemporal clustering models and the UCERF3-TD finite fault models with elastic rebound. The model was used on demand in response to the September 2016 Bombay Beach swarm, influencing the CPEC response. Operationalization efforts expanded to include hazard calculations, with a comprehensive set of potential products presented to the user community. Development also continued on an Operational Aftershock Forecast which automatically calculates Reasenberg & Jones (1989) statistics for events in the USGS ComCat earthquake catalog. CyberShake collaboration has also been strong in this report period, primarily in support of the Utilization of Ground Motion Simulations committee and Study 17.3, the first central California CyberShake study.
Intellectual Merit The UCERF3-ETAS model implemented in OpenSHA was published in BSSA in February 2017. Typical short term clustering models do not consider the proximity to known faults when assessing the probability of a large aftershock, though CEPEC has recognized its importance. UCERF3-ETAS is the first model to couple ETAS statistics with a full fault based long term earthquake forecast, illustrating both the advantages and challenges therein. One significant UCERF3-ETAS discovery is the need for elastic rebound in fault based ETAS simulations. Without a rebound mechanism, ruptures are likely to trigger themselves which results in unrealistic, or even runaway sequences in the case of particularly characteristic faults.
Broader Impacts The UCERF3-ETAS model informed the CPEC response to the September 2016 Bombay Beach swarm. The statement issued by CPEC included a probability range across 3 models, one of which was UCERF3-ETAS. This statement received broad media attention. Additionally the model and its potential products was presented to the user community at an April 2017 USGS Powell Center meeting, with participation from FEMA, public utilities, and the insurance/loss modeling community.
Exemplary Figure Figure 1
Hazard map computed from UCERF3-ETAS simulation of seismicity following a M7 earthquake on the Mojave S section of the San Andreas Fault. Plot shows the probability of exceeding Modified Mercalli Intensity (MMI) 8 (severe) in the week immediately following the scenario Mojave M7 event.
Credits: Kevin Milner (USC)