Is there a relationship between large earthquakes that occur along major fault zones and nearby volcanic eruptions?
Sometimes, yes. A few historic large regional earthquakes (>M 6) are considered by scientists to be related to a subsequent eruption or to some type of unrest at a nearby volcano. The exact triggering mechanism for these historic examples is not well understood, but the volcanic activity probably occurs in response to a change in the local pressure surrounding the magma reservoir system as a consequence of either severe ground shaking caused by the earthquake or a change in the “strain” or pressure in the Earth’s crust in the region surrounding where the earthquake occurred. For example, on November 29, 1975, a large magnitude-7.2 earthquake struck the Big Island of Hawaii at 4:48 a.m. It was centered about 28 kilometers southeast of Kilauea Volcano’s summit caldera at a depth of 5 kilometers; the earthquake occurred within the volcano’s south flank. The earthquake was preceded by numerous foreshocks, the largest of which was a 5.7 magnitude jolt at 3:36 a.m. the same morning, and was
