Volcanic unrest leading to the July-August 2001 lateral eruption at Mt. Etna: Seismological constraints

摘要

A close relationship between earthquake swarms, volcanic eruptions, and ground deformation at Mt. Etna was well documented shortly before the beginning of the July-August 2001 eruption. Past experiences at this volcano suggest how magma/dike intrusion in the shallow crust or in the upper part of the volcanic pile normally occurs after several years/months of internal recharging. Since seismic investigations provide a means to study the scale and origin of stress perturbations at active volcanoes, allowing to better investigating the preparation phase of an eruption, in this paper, we performed a close examination of the seismic activity recorded at Mt. Etna in the months preceding the 2001 eruption and in particular between November 2000 and July 2001. After integrating data recorded by the two networks operating during that time and run by the Istituto Intemazionale di Vulcanologia and SISTEMA POSEIDON, we relocated 522 earthquakes by using the tomoDD code in a 3D velocity model, and then we computed their fault plane solutions. The application of different selection criteria enabled obtaining a good-quality revised data set consisting of 111 fault plane solutions.