SCEC Award Number 12169 View PDF
Proposal Category Workshop Proposal
Proposal Title CSEP Workshop: Final Evaluation of the Regional Earthquake Likelihood Models (RELM) Experiment
Investigator(s)
Name Organization
Maximilian Werner Princeton University J. Douglas Zechar University of Southern California Danijel Schorlemmer University of Southern California Thomas Jordan University of Southern California Edward Field United States Geological Survey
Other Participants CSEP & RELM Working Groups
SCEC Priorities 2b, 2e, 4e SCEC Groups CSEP, WGCEP, EFP
Report Due Date 07/07/2012 Date Report Submitted N/A
Project Abstract
 The topics of this two-day workshop held June 6-7 in Rancho Mirage, California, were (i) a thorough evaluation of the five-year Regional Earthquake Likelihood Models (RELM) initiative, (ii) lessons for the design of future forecast evaluations, and (iii) operational earthquake forecasting and validation. The RELM experiment, conducted within the Collaboratory for the Study of Earthquake Predictability (CSEP) at SCEC, helped clarify many ideas about how to conduct earthquake forecast evaluations; it sparked further research into model development and evaluation; and served as a blueprint for numerous similar experiments within CSEP around the globe. This workshop facilitated the dissemination of the RELM results and provided a forum for the discussion and future planning of earthquake predictability studies. Several important avenues for future research were identified, including finite-size rupture and improved short-term forecasting experiments. These are important because of their relevance for hazard purposes (e.g., for the Uniform California Earthquake Rupture Forecast and Operational Earthquake Forecasting by official agencies) and as probes into the physics of earthquake triggering (e.g., Coulomb stress transfer).
Intellectual Merit This workshop served as a forum for the dissemination, discussion and interpretation of the RELM results among RELM and CSEP modelers, testers and those interested more broadly in the predictability of earthquakes. We discussed the significance of the results in terms of the underlying models of earthquake occurrence and their implications for seismogenesis and seismic hazard. We also identified lessons from the RELM experiment for current and future forecasting experiments. These lessons benefit ongoing CSEP experiments around the globe (e.g., in China, Italy, Japan and New Zealand). Another objective of the workshop was to discuss the implementation, real-time operation and validation of near-term probabilistic earthquake forecasts for the purpose of providing the public with authoritative, dynamic and scientifically accurate information about seismic hazard. This workshop helped focus the community on some of the challenges and opportunities for generating and evaluating such forecasts.
Broader Impacts The study of earthquake predictability is critical for society because seismic hazard assessments, which inform policy decisions, can be evaluated and improved, and because the predictive skills of hypotheses and models are a fundamental demonstration of scientific accuracy and usefulness. The earthquake forecasting experiment designed by the RELM working group (and implemented and expanded within CSEP) provides a reproducible, transparent and scientifically rigorous (via prospective forecasts) example of procedures to establish predictive skill of hypotheses of earthquake occurrence. This workshop helped advanced our understanding of the current level of predictive skill of such hypotheses and provided an opportunity to coordinate research into further improvements.
Exemplary Figure Figure 3 [from Zechar et al., 2012, in press in Bull. Seismol. Soc. Am.). Results of consistency tests for RELM mainshock forecasts. Red points indicate that the forecast failed the test and green points indicate that the forecast passed the test. Horizontal black lines delimit the 95% confidence “pass” region. a) Results of the two-sided N-test, where the forecast number of target earthquakes is indicated as the middle vertical dash on each horizontal line, and the observed number of target earthquakes is indicated by the filled circle. The circle is not in the same place for all forecasts due to masking. b-d) Results of the one-sided L (S,M)-test; circles represent the observed space-rate-magnitude (space, magnitude) log-likelihood for each forecast and the horizontal black lines delineate the top 95% of log-likelihoods from simulated catalogs that are consistent with the forecast.