Hydrothermal systems characterization of the Stromboli volcano using spatial and temporal changes of the seismic velocities

Abstract

Geophysical and geochemical networks are routinely deployed on active volcanoes to observe and monitor unrest periods. However, changes of the physical parameters with time are related to either magma/fluid movement or variations occurring in the hydrothermal systems hosted in the volcanic edifice. Here we use four years of ambient seismic noise recorded at the Stromboli volcano to reconstruct its shallow structure using the ambient noise cross-correlation method. At the same time, we detect temporal variations of the seismic velocities associated with the volcanic activity. We correlated the most reliable variations both in space and in time with other seismic and geochemical information in order to identify lapses of time of general unrest. We also implemented a method to enhance their spatial visualization for the interpretation. We found that the spatial mapping of the seismic velocity temporal variations obtained processing the data at high frequency (1.5–2.5 Hz) match with the location of the main hydrothermal reservoirs of the volcano. This suggests that there is a relationship between volcanic activity and hydrothermal areas that can be detected and monitored for a better understanding of the volcanic phenomena