Seismic Monitoring of Active Rock Fall Source Areas in the Yosemite National Park

Between 1857 and 2007 moe than 600 landslide events hav been documented in Yosemite National Park with the vast majority of events occurring as rock falls in Yosemite Valley. Teh conditions leading to and triggering rock fall are unerstood in approximately 50% of cases, but in the other 50%, there were no apparent triggers. Occasionally, larg rock falls have been preceded by smaller events that in retrospect may have been precursors. Close range seismic monitoring presents an opportunity to study the conditons leading up to rock fall, as well as the mechanics of the actual rock fall as recorded seismically.