Seismic surveillance at Vulcano by use of a portable digital array: features of the seismicity and relocation of the events in a 3-D heterogeneous structure

Abstract

A considerable rise in temperature in the fumarolic gases, observed at Vulcano throughout 1988, was not accompanied by correlated geophysical markers indicating clear renewal of the volcanic activity Microseismicity remained at very low energy levels and was monitored during two months by use of a temporary array of three-component digital stations, in addition to the permanent seismic network of the Aeolian Islands. Comparison of the seismic activity recorded dunng thls experiment with the seismicity detected during a previous survey carried out in 1987, suggests that no substantial changes occurred in both the hypocentral volumes and energy release. Relocation of the events within a three-dimensionally heterogeneous medium, observation of waveforms similarities and kinematic analysis for reconnalssance of the seismic phases allow to draw a preliminary quantitative picture of the seismic behaviour of the volcanic field during the survelllance period.