SCEC Award Number 21049 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Global Earthquake Activity Rate Model
Name Organization
David Jackson University of California, Los Angeles
Other Participants Han Bao
SCEC Priorities 5a, 5b, 5d SCEC Groups EFP, Seismology, SAFS
Report Due Date 03/15/2022 Date Report Submitted 03/06/2022
Project Abstract
The objects of the project (called GEAR) are (1) to construct and test a forecast model (rate of earthquake epicenters within location, magnitude, and time windows) at high resolution (0.1 by 0.1 degree), over the whole earth surface, for events of magnitude threshold 5.0, 5.8 and 7.0; (2) to compare GEAR results to those of other global and/or regional forecasts; and (3) to identify spatial and temporal conditions in which observed earthquake rates are substantialy higher or lower than forecasted.
GEAR rates are inferred from a weighted combination of smoothed seismicity and tectonic deformation estimated from plate tectonic and geodetic data. The forecast rate is submitted once, for testing prospectively over an indefinite time interval (decades) against earthquakes reported in the Global Central Moment Tensor (GCMT) earthquake catalog. Magnitudes are assumed to follows the Tapered Gutenberg-Righter distribution with one of five corner magnitude values depending on regional tectonics. The first version (GEAR1) was published in 2015 and submitted to the Collaboratory for Study of Earthquake Predictability (CSEP) for testing. We now use an adapted version based on the PDE catalog which is complete to magnitude 5.0 and thus contains many more earthquakes than the GCMT.
Our subsequent aims have been to explore magnitude distributions and other assumptions using our own statistical tests, and to compare GEAR results with regional forecasts for California.
Intellectual Merit Our project explores the extent to which prior earthquake forecasts, based on common assumptions, agree with earthquake occurrence before and after the forecasts, contributing to the understanding of earthquake processes. We also developed methods for associating finite ruptures on faults with prescribed descriptions of such events, a necessary step in evaluating forecasts of such events, and we tested some of these ideas on forecasts of the Working Group on California Earthquake Probabilities (WGCEP). Association and testing of finite ruptures have been major goals of the Collaboratory for Study of Earthquake Predictability (CSEP).
Broader Impacts Our research affects seismic hazard and risk estimation, with implications for public safety, risk management, and public policy. We’ve presented our results to students and faculty at universities, including UCLA, UC Riverside, ETH Zurich, EFZ Potsdam, Victoria Univerity Wellington; at SCEC Annual meetings, the Seismological Society of America, and the American Geophysical Union.
We show that Physics, Geology, Geodesy, and Statistics can be combined to solve real world problems. We’ve discussed our analysis with students and faculty in Statistics, showing them applications and encouraging their participation in seismological research.
Exemplary Figure Figure 4. Maps of 2015 GEAR1 rate forecast, its two parent forecasts, and the ratio of the Seismic to Tectonic forecasts. The color code on the top row applies to the upper left, upper right, and bottom left diagrams.. The color code on the lower right corresponds to the lower right diagram. Squares show earthquakes after 1977. Green, white, and blue squares correspond to most, intermediate, and least earthquakes expected ones.