Waveform Variation of the Explosion-Quakes as a function of the eruptive activity at Stromboli Volcano

Abstract

In the period from June to September 2011, the Stromboli volcano was affected by an activity characterized by an increase of the volcanic tremor amplitude, in the magnitude of explosions and with some lava overflows. In order to examine and understand in more detail this particular phase of the volcano, we present here an unsupervised investigation of the waveform variation of the explosion-quakes recorded during this period. The aim is to identify a possible relationship between the temporal changes of these events and the volcano seismic activity. The analysis is performed on a dataset of about 8400 explosion-quakes by using a SOM neural network. This technique works well with large datasets allowing to find out unpredicted characteristics among them. The SOM clustering highlights sudden changes occurring at the end of July and of August and a permanent variation between June and September reflecting a modification in the volcano activity. These results could be interesting for focusing the analysis of the seismological dataset in these intervals in order to evidence minor, but important variations, which were previously undetected and to improve the knowledge on the explosive dynamics of the volcano.