An Overview of the 3rd Uniform California Earthquake Rupture Forecast (UCERF3)

Edward H. Field, & Other WGCEP Participants

Submitted August 14, 2017, SCEC Contribution #7578, 2017 SCEC Annual Meeting Poster #018

Previous fault-based earthquake forecast models have generally assumed segmentation, excluded multi-fault ruptures, and ignored spatiotemporal clustering (aftershocks and otherwise triggered earthquakes), each of which has been brought into question by recent earthquakes.  The Working Group on California Earthquake Probabilities ( has addressed all these issues in their most recent model: the Third Uniform California Earthquake Rupture Forecast (UCERF3), which is the first complete fault-based model to provide self-consistent rupture probabilities over forecasting intervals from less than an hour to more than a century, and the first capable of evaluating the short-term hazards due to multi-event sequences of complex faulting.  We find that combining a fault-based forecast with statistical seismology clustering models (e.g., ETAS) requires both characteristic magnitude-frequency distributions on faults (non-Gutenberg-Richter), as well as the inclusion of elastic rebound, apparently settling debates on whether either of these attributes is required. All models embody assumptions, approximations, and uncertainties, so the USGS is currently exploring whether the model is right enough to be useful, and useful enough to warrant deployment as an operational earthquake forecasting system.

Key Words
Earthquake Forecast, OEF

Field, E. H., & WGCEP Participants, . (2017, 08). An Overview of the 3rd Uniform California Earthquake Rupture Forecast (UCERF3). Poster Presentation at 2017 SCEC Annual Meeting.

Related Projects & Working Groups
Working Group on California Earthquake Probabilities (WGCEP)