Publication Date:
2023-08-31
Description:
Volcanic eruptions are key scenarios for developing new tools for volcanic monitoring. Among the geophysical techniques, electromagnetic methods are not extensively used in volcano monitoring. However, these methods are very sensitive to temporal changes in the subsoil due to the movement of fluids, which strongly affects the electrical resistivity of the subsoil. During the volcanic eruption that started on the island of La Palma on September 19th, 2021, and the subsequent post-eruptive process, we deployed several magnetotelluric (MT) stations in the vicinity of the new volcano to test the performances of such instrumentation as an effective volcanic monitoring tool. Magnetotelluric stations have been installed for continuous monitoring, recording electric and magnetic fields along the N-S and E-W directions. We have obtained good quality transfer functions for the period range of 0.01 - 100 s. The main objective of this MT experiment was to detect possible variations of the apparent resistivity and phase curves and to compare them with other geophysical and geochemical studies conducted in the same area. The preliminary results show slight changes in the resistivity over time that could be related to the development of a shallow hydrothermal system around the volcano. Furthermore, in comparing the pre-eruptive 3D resistivity model of the island, we observed that regions with low resistivity were almost aseismic, possibly due to the presence of ductile rocks like clays.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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