Influence of permeability on the hydrothermal system at Vulcano Island (Italy): inferences from numerical simulations

Santina Chiara Stissi,Rosalba Napoli,Giordano Montegrossi,Gilda Currenti,Andrey Afanasyev

doi:10.1186/s40623-021-01515-z

Abstract

Volcano-hydrothermal systems are governed by complex interactions between fluid transport, and geochemical and mechanical processes. Evidence of this close interplay has been testified by distinct spatial and temporal correlations in geochemical and geophysical observations at Vulcano Island (Italy). To understand the interaction between fluid circulation and the geochemical and geophysical manifestations, we perform a parametric study to explore different scenarios by implementing a hydro-geophysical model based on the equations for heat and mass transfer in a porous medium and thermo-poroelastic theory. Numerical simulations allow us to define the controlling role of permeability distribution on the different modeled parameters as well as on the geophysical observables. Changes in the permeability within the highly fractured crater area could be responsible for the fluctuations in gas emission and temperature recorded during the crisis periods, which are accompanied by shallow volcano-seismicity in the absence of significant deformation and gravity variations. Despite the general medium permeability of the volcanic edifice, the presence of more highly permeable pathways, which allow the gas to rapidly escape, as testified by the presence of a well-developed fumarolic field, prevents the pressure buildup at shallow depths.Graphic abstract

Highlights

In recent decades, a number of efforts have been made to improve the comprehension of the interplay between fluid flow and mechanical rock response (Chiodini et al 2016; Ingebritsen et al 2010; Rinaldi et al 2010; Tanaka et al 2018; Troiano et al 2011)
Thermo-poro-elastic approaches, coupling fluid flow and rock strain, have been explored in several volcano geothermal areas, which have demonstrated the important role of elastic and transport properties in leading to changes in geochemical and geophysical observables at the surface related to hydrothermal activity (Chiodini et al 2016; Peiffer et al 2018; Rinaldi et al 2010; Tanaka et al 2018)
Discussions and conclusions The complex interplay among fluid transport, geochemical, and mechanical processes controls the dynamics of volcano-hydrothermal systems and regulates the spatial–temporal evolutions of geochemical and geophysical observables at the ground surface

Summary

Introduction

A number of efforts have been made to improve the comprehension of the interplay between fluid flow and mechanical rock response (Chiodini et al 2016; Ingebritsen et al 2010; Rinaldi et al 2010; Tanaka et al 2018; Troiano et al 2011). Temperature (T), pressure (P), and gas saturation ( Sg ) distributions obtained in the steady state (Additional file 1: Fig. S1) and for an unrest phase (Fig. 2) are evaluated in all the model domain for both HP and LP configurations.

Results

Conclusion