The influence of great earthquakes on volcanic eruption rate along the Chilean subduction zone

Seismic activity has been postulated as a trigger of volcanic eruption on a range of timescales, but demonstrating the occurrence of triggered eruptions on timescales beyond a few days has proven difficult using global datasets. Here, we use the historic earthquake and eruption records of Chile and the Andean southern volcanic zone to investigate eruption rates following large earthquakes. We show a significant increase in eruption rate following earthquakes of M-W>8, notably in 1906 and 1960, with similar occurrences further back in the record. Eruption rates are enhanced above background levels for similar to 12 months following the 1906 and 1960 earthquakes, with the onset of 3-4 eruptions estimated to have been seismically influenced in each instance. Eruption locations suggest that these effects occur from the near-field to distances of similar to 500 km or more beyond the limits of the earthquake rupture zone. This suggests that both dynamic and static stresses associated with large earthquakes are important in eruption-triggering processes and have the potential to initiate volcanic eruption in arc settings over timescales of several months. (C) 2008 Elsevier B.V. All rights reserved.