Location of the source and shallow velocity model deduced from the explosion quakes recorded by two seismic antennas at Stromboli volcano

The seismic wavefield associated to the ongoing eruptive activity at Stromboli volcano (Italy) is investigated using data from two small-aperture, short-period seismic arrays deployed on the northern and western flanks, located at about 1.7 km from the active craters. Two distinct approaches are used to analyze the recorded signals:

• 1.1) the zero-lag cross-correlation method is used to analyze the explosion quakes data, to estimate slowness and backazimuth as a function of lapse time;
• 2.2) multiple filter technique and phase matched filtering are used to estimate Rayleigh wave dispersion, to obtain a shallow velocity model of the two sites.

Estimates of slowness vectors at the two different array sites show a primary (volcanic) source located at shallow depth beneath the crater region. Secondary sources associated with path effects are located in close proximity of the sector graben of Sciara del Fuoco and of the old parasitic cone of Timpone del Fuoco. The shallow velocity structure derived for the western flank depicts striking resemblance with that previously inferred for the northern flank of the volcano.