Earth tides can trigger shallow thrust fault earthquakes

Science. 2004 Nov 12;306(5699):1164-6. doi: 10.1126/science.1103961. Epub 2004 Oct 21.

Abstract

We show a correlation between the occurrence of shallow thrust earthquakes and the occurrence of the strongest tides. The rate of earthquakes varies from the background rate by a factor of 3 with the tidal stress. The highest correlation is found when we assume a coefficient of friction of mu = 0.4 for the crust, although we see good correlation for mu between 0.2 and 0.6. Our results quantify the effect of applied stress on earthquake triggering, a key factor in understanding earthquake nucleation and cascades whereby one earthquake triggers others.