Aeolian Islands, Italy (38.79 N, 15.21 E)
(This report is relative to the period 13.01 - 04.04.1995)
Last report (see Bullettin, v. 20, n.1) described the seismic activity at Stromboli until 9 December 1994. The day after, due to funding problems, the power supply of the acquisition PC was interrupted. The activity of the station resumed only on 13 January 1995. Unfortunately, the funding problems still remain; for this reason we don't know for how long these reports, which began on October 1989, could be sent for publication to the Smithsonian Institution.
During the second half of January the seismic activity showed a behaviour not too different from the one recorded at the beginning of December, with few major shocks and average activity in terms of total number of events and tremor intensity.
February was characterized by a greater number of major shocks, although not reaching the frequency recorded in November 1994 (see Bullettin, v. 20, n.1). On 26 February the tremor intensity began to decrease, and for a few days its average value remained stable below 3 Volts x Seconds. In the meanwhile the number of major shocks was still considerable.
On 5 March, at 17.40 GMT, a big explosion accompanied the return of the tremor intensity to more usual values, around 5 Vs. The explosion threw pyroclastic material towards Forgia Vecchia and Fossetta, a depression SW of the crater area. The ejecta reached a sufficient height in order to be clearly seen from the village of Stromboli, where the explosion was strongly felt.
After the strong explosion the tremor level continued to increase; after a short decrease, it reached a peak of 10.8 Vs on 30 March. The number of major shocks showed a slight decrease.
It is noteworthy that the raise of the tremor intensity after the big event did not match the behaviour recorded after the two paroxysmal phases of 10 February 1993 (see Bullettin, v. 18, n. 1 & 2) and 16 October 1993 (see Bullettin, v. 18, n. 9); in those occasions a remarkable decrease of all the seismicity, and of the tremor level in particular, could be noted immediately after the events.
Throughout the period examined in this report the total number of shocks did not show significant variations.
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