Villarrica volcano (Chile): characteristics of the volcanic tremor and forecasting of small explosions by means of a material failure method

Villarrica volcano (Chile, 39.42°S, 71.93°W) is one of the most active volcanoes in the Andes. It shows persistent strombolian activity in a small lava lake situated at the bottom of the summit crater. From September to December 2000, the volcano exhibited anomalous behaviour: after a regional tectonic seismic event on 22 September, the eruption of a small volume of lava apparently plugged the conduit. This situation then lasted for ten days. On 5 and 8 October, a series of explosions reopened the system. This eruption behaviour has allowed us to study the evolution of the characteristic tremor in the open and closed states of the conduit: a shift in the peak frequency from 1 Hz (open) to 2 Hz (closed). The explosions related to the opening of the conduit were forecasted by means of a material failure method.