Overview

Extreme ground motions are the very large amplitudes of earthquake ground motions that can arise at very low probabilities of exceedance, as was the case for the 1998 PSHA for Yucca Mountain.  The Extreme Ground Motion (ExGM) project investigates the credibility of such ground motions through studies of physical limits to earthquake ground motions, unexceeded ground motions, and frequency of occurrence of very large ground motions or of earthquake source parameters (such as stress drop and faulting displacement) that cause them. The purpose of this project is seek physical limits on the amplitude of strong ground motion in rock, and is motivated by the issue of ground motion levels at very low probability levels at Yucca Mountain. This project is sponsored by the U.S. Department of Energy. The main SCEC discipline and focus groups that will work on this project are Geology – especially fault zone geology; Fault and Rupture Mechanics of earthquakes, and Ground Motion Prediction. This project is also discussed above within Seismic Hazard and Risk Analysis.