Tidal triggering of microearthquakes on the Juan de Fuca Ridge

Abstract
Tidal stresses beneath the oceans can be up to an order of magnitude higher than those found in the continents because of the effects of loading by ocean tides. I have analyzed 1899 microearthquakes recorded during a 55‐day experiment on the Endeavour segment of the Juan de Fuca Ridge for tidal triggering. The tidal phase of the full data set and of a declustered subset comprising 987 events appears non‐random to a high level of confidence. Earthquakes occur more frequently near low tides, especially the lowest spring tides, when the extensional stresses are a maximum in all directions.