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Short- and long-term velocity variations and strain evolution at Ischia (ITALY) and their implications for dynamics of the hydrothermal system
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  • Stefania Tarantino,
  • Piero Poli,
  • Maurizio Vassallo,
  • Nicola D'Agostino
Stefania Tarantino
Istituto Nazionale di Geofisica e Vulcanologia

Corresponding Author:[email protected]

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Piero Poli
Universita Di Padova
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Maurizio Vassallo
Istituto Nazionale di Geofisica e Vulcanologia
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Nicola D'Agostino
Istituto Nazionale di Geofisica e Vulcanologia
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In active volcanic systems, the elevated pressurization of fluids and the movement of melt materials have an enormous influence on the stress-state of rocks and their mechanical behavior. We use seismic ambient noise to evaluate the static seismic velocity variations related to long-term volcanic deformation, and the dynamic changes associated with the 2017 Casamicciola earthquake (Mw 3.9), in the active volcanic complex of the Ischia Island (Italy). Our study reveals a significant dynamic velocity reduction mostly related to the near-surface damage, with a permanent drop near the red zone, that we posit to be related to the documented landslides and the subsidence observed immediately after the earthquake. We also report a positive long-term linear trend of velocity variations, sensitive to a generalized contraction of the Ischia Caldera that we revealed with geodetic modeling. Our results suggest a depressurization of the shallow hydrothermal system, through degassing along faults or sills.
01 Mar 2024Submitted to ESS Open Archive
05 Mar 2024Published in ESS Open Archive