Evaluating the Significance of Changes in the Gutenberg-Richter b-value in Western North America

Abstract:

Earthquake precursors have long been sought out as a means to predict earthquakes with very limited success. Recently it has been found that a drop in Gutenberg-Richter b-value after a M_w 6 earthquake is predictive of a mainshock of larger magnitude. We analyze the temporal changes in the frequency-magnitude distribution systematically for every M_w 6+ earthquake sequence in the USGS Earthquake Catalog for Western North America. We then consider smaller events, those with a potential foreshock magnitude as small as M_w 5, and repeat the analysis to assess its performance for events that modify stresses over smaller spatial regions. We also consider recent earthquakes in California and Nevada and apply the method in real time, making predictions for these events. Finally, we discuss whether this analysis is consistent with the requirements of the IASPEI procedure to evaluate earthquake precursors and whether changes in b-value are a useful tool for earthquake prediction.