“Is this eruption related to that earthquake?” That’s a question commonly asked of volcanologists and seismologists when a newsworthy volcanic eruption develops within days or weeks following a newsworthy earthquake somewhere else in the world. Accurate answers are important: Continued scientific advances in understanding tectonic and magmatic processes and their interaction are fundamental to providing reliable information on the nature of hazards that large earthquakes and volcanic eruptions pose to many population centers around the globe.
Traditional answers to the question are of the form, “Not likely. The stress changes from that earthquake are too small—smaller than stresses associated with the solid-earth tides (about 0.001 MPa)—to influence processes at this volcano. Furthermore, the temporal patterns of volcanic eruptions and earthquakes appear to be stochastic, and statistically independent sequences occasionally produce events that are nearly coincident in time.” Such answers are based largely on calculations that model earthquakes as shear dislocations—that...
