9725562 Tullis The P.I.s propose an experimental program focussed on understanding fundamental processes that may be responsible for causing earthquakes to occur. Crustal earthquakes occur due to rapid sliding on faults, and they occur suddenly because it is harder for the sliding to begin than for it to continue once it has started. The experiments proposed will aim at trying to understand why sliding is easier when it occurs faster, and why faults grow stronger as they sit quietly between earthquakes. Several fundamental explanations have been offered, and these laboratory experiments on friction of rock will be testing some of the predominant hypotheses. Ultimately it is hoped that improving understanding of fundamental earthquake processes might show ways of predicting earthquakes and understanding the origin of the damaging strong ground motions. ***
