Pseudo-Prospective Evaluation of Operational UCERF3-ETAS Forecasts during the Ridgecrest, California, Earthquake Sequence

William H. Savran, Maximilian J. Werner, David A. Rhoades, David D. Jackson, Edward H. Field, Kevin R. Milner, Andrew J. Michael, Thomas H. Jordan, & Philip J. Maechling

Submitted August 14, 2019, SCEC Contribution #9576, 2019 SCEC Annual Meeting Poster #269

The Ridgecrest earthquake sequence began with a Mw6.4 earthquake that occurred on July 4, 2019, and was followed within 36 hours by a Mw7.1 earthquake. The sequence included the largest earthquake in California since the 1999 Mw7.1 Hector Mine and the first significant California earthquake since the USGS began their operational earthquake forecasting program. Deployed forecast models ranged in complexity from a simple Reasenberg-Jones model to the Uniform California Earthquake Rupture Forecast Version 3 – Episodic Type Aftershock Sequence (UCERF3-ETAS) and Coulomb-stress based models. Forecasts were computed rapidly following the initial Mw6.4 event and repeatedly updated. The first UCER3-ETAS forecasts were produced within hours of the initial event. The sequence provides an opportunity to evaluate operational forecasts in a pseudo-prospective sense and to provide some insight into the skill of these forecasts using near-real-time data products such as catalogs and finite source models. We use new evaluation metrics developed within the second phase of the Collaboratory for the Study of Earthquake Predictability (CSEP2) that consider the full distribution of earthquake. We focus evaluations on the forecasts produced by UCERF3-ETAS, the first model to integrate short-term clustering with long-term fault kinematics. We conclude with thoughts about truly prospective testing of OEF models, inconsistencies between observations and forecasts, and the influence of real-time data product quality on forecast quality.

Key Words
Earthquake Forecasting, Ridgecrest Sequence, Statistical Seismology, CSEP

Citation
Savran, W. H., Werner, M. J., Rhoades, D. A., Jackson, D. D., Field, E. H., Milner, K. R., Michael, A. J., Jordan, T. H., & Maechling, P. J. (2019, 08). Pseudo-Prospective Evaluation of Operational UCERF3-ETAS Forecasts during the Ridgecrest, California, Earthquake Sequence. Poster Presentation at 2019 SCEC Annual Meeting.


Related Projects & Working Groups
Ridgecrest Earthquakes