Two-dimensional seismic attenuation images of Stromboli Island using active data

Abstract

In this work we present intrinsic and scattering seismic attenuation 2-D images of Stromboli Volcano. We used 21,953 waveforms from air gun shots fired by an oceanographic vessel and recorded at 33 inland and 10 ocean bottom seismometer seismic stations. Coda wave envelopes of the filtered seismic traces were fitted to the energy transport equation in the diffusion approximation, obtaining a couple of separate Qi and Qs in six frequency bands. Using numerically estimated sensitivity kernels for coda waves, separate images of each quality factor were produced. Results appear stable and robust. They show that scattering attenuation prevails over intrinsic attenuation. The scattering pattern shows a strong concordance with the tectonic lineaments in the area, while an area of high total attenuation coincides with the zone where most of the volcanic activity occurs. Our results provide evidence that the most important attenuation effects in volcanic areas are associated with the presence of geological heterogeneities.