Earthquake-induced thermal anomalies at active volcanoes

Answering the question whether a regional earthquake can trigger or enhance volcanic activity requires a systematic measure of volcanic activity. One such measure is heat flux. The availability since A. D. 2000 of a satellite-derived heat flux inventory for global volcanism allows us to explore how earthquakes and volcanic activity may be linked. Examination of 7 yr of global volcanic heat flux data reveals 37 volcanic responses to regional earthquakes. Each response is expressed by an increase in heat flux within 1-21 days of the triggering earthquake. Whether a volcano responds depends on earthquake magnitude, distance to the epicenter, and orientation of the earthquake focal mechanism in respect to the volcano: the focal mechanism has to align with the responding system. Of the 7 global major increases of seismic energy during 2000-2006, 4 were followed by a global volcanic heat flux increase. The largest response involved a 300% increase and followed the largest earthquake in the period, the 2004 Sumatra-Andaman (Indonesia) earthquake, moment magnitude, M-W = 9.3.