Modeling of recent volcanic episodes at Phlegrean Fields (Italy): geochemical variations and ground deformation

Todesco, Micol; Rutqvist, Jonny; Chiodini, Giovanni; Pruess, Karsten; Oldenburg, Curtis M.

doi:10.1016/j.geothermics.2003.08.014

Cited by 102 publications

(73 citation statements)

References 34 publications

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“…When hydrothermal fluids from a magma reservoir are injected into surrounding rocks, hydraulic head in the hydrothermal systems will rise and the ground will be uplifted (e.g. Todesco et al, 2004;Hurwitz et al, 2007;Rinaldi et al, 2010;Fournier and Chardot, 2012), while strain due to chamber inflation generally leads to a water level fall together with ground uplift. Temperature sensors in monitoring wells provide additional valuable information, as hydrothermal fluid injections should lead to relatively fast temperature effects compared to heat transferred from an inflating chamber or a dyke intruding through the crust, which would reach the aquifer much later -in fact, after the poroelastic response is already equilibrated.…”

Section: General Considerationsmentioning

confidence: 99%

“…Numerical modelling of pressure changes in hydrological systems has focused on pressure and temperature transients in hydrothermal systems and resulting ground deformation due to the injection of hot magmatic fluids, using one-way coupling of solid deformation and porous flow (e.g. Todesco et al, 2004;Hurwitz et al, 2007;Hutnak et al, 2009;Rinaldi et al, 2010;Fournier and Chardot, 2012). Rutqvist et al (2002) have developed a two-way coupled code and applied it to problems related to carbon dioxide injection in aquifers and the disposal of nuclear waste in porous media.…”

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confidence: 99%

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Poroelastic responses of confined aquifers to subsurface strain and their use for volcano monitoring

2015

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Abstract. Well water level changes associated with magmatic unrest can be interpreted as a result of pore pressure changes in the aquifer due to crustal deformation, and so could provide constraints on the subsurface processes causing this strain. We use finite element analysis to demonstrate the response of aquifers to volumetric strain induced by pressurized magma reservoirs. Two different aquifers are invoked -an unconsolidated pyroclastic deposit and a vesicular lava flow -and embedded in an impermeable crust, overlying a magma chamber. The time-dependent, fully coupled models simulate crustal deformation accompanying chamber pressurization and the resulting hydraulic head changes as well as flow through the porous aquifer, i.e. porous flow. The simulated strain leads to centimetres (pyroclastic aquifer) to metres (lava flow aquifer) of hydraulic head changes; both strain and hydraulic head change with time due to substantial porous flow in the hydrological system.Well level changes are particularly sensitive to chamber volume, shape and pressurization strength, followed by aquifer permeability and the phase of the pore fluid. The depths of chamber and aquifer, as well as the aquifer's Young's modulus also have significant influence on the hydraulic head signal. While source characteristics, the distance between chamber and aquifer and the elastic stratigraphy determine the strain field and its partitioning, flow and coupling parameters define how the aquifer responds to this strain and how signals change with time.We find that generic analytical models can fail to capture the complex pre-eruptive subsurface mechanics leading to strain-induced well level changes, due to aquifer pressure changes being sensitive to chamber shape and lithological heterogeneities. In addition, the presence of a pore fluid and its flow have a significant influence on the strain signal in the aquifer and are commonly neglected in analytical models. These findings highlight the need for numerical models for the interpretation of observed well level signals. However, simulated water table changes do indeed mirror volumetric strain, and wells are therefore a valuable addition to monitoring systems that could provide important insights into preeruptive dynamics.

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Section: General Considerationsmentioning

confidence: 99%

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confidence: 99%

Poroelastic responses of confined aquifers to subsurface strain and their use for volcano monitoring

2015

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“…[4] Recent numerical modeling studies have indeed demonstrated that rates of GSD measured by geodetic techniques could theoretically be induced by poroelastic transients in the shallow hydrothermal system [Hurwitz et al, 2007;Todesco et al, 2004]. Todesco et al [2004] carried out simulations using a multiphase, multicomponent (H 2 O-CO 2 ) fluid to describe the recent evolution of a shallow (1.5 km deep) hydrothermal system in the Campi Flegrei Caldera (Italy), and Hurwitz et al [2007] carried out simulations using a single-component (H 2 O) fluid with the goal of determining the range of plausible conditions under which poroelastically induced GSD might occur.…”

Section: Introductionmentioning

confidence: 99%

“…Todesco et al [2004] carried out simulations using a multiphase, multicomponent (H 2 O-CO 2 ) fluid to describe the recent evolution of a shallow (1.5 km deep) hydrothermal system in the Campi Flegrei Caldera (Italy), and Hurwitz et al [2007] carried out simulations using a single-component (H 2 O) fluid with the goal of determining the range of plausible conditions under which poroelastically induced GSD might occur.…”

Section: Introductionmentioning

confidence: 99%

Numerical models of caldera deformation: Effects of multiphase and multicomponent hydrothermal fluid flow

et al. 2009

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[1] Ground surface displacement (GSD) in large calderas is often interpreted as resulting from magma intrusion at depth. Recent advances in geodetic measurements of GSD, notably interferometric synthetic aperture radar, reveal complex and multifaceted deformation patterns that often require complex source models to explain the observed GSD. Although hydrothermal fluids have been discussed as a possible deformation agent, very few quantitative studies addressing the effects of multiphase flow on crustal mechanics have been attempted. Recent increases in the power and availability of computing resources allow robust quantitative assessment of the complex time-variant thermal interplay between aqueous fluid flow and crustal deformation. We carry out numerical simulations of multiphase (liquid-gas), multicomponent (H 2 O-CO 2 ) hydrothermal fluid flow and poroelastic deformation using a range of realistic physical parameters and processes. Hydrothermal fluid injection, circulation, and gas formation can generate complex, temporally and spatially varying patterns of GSD, with deformation rates, magnitudes, and geometries (including subsidence) similar to those observed in several large calderas. The potential for both rapid and gradual deformation resulting from magma-derived fluids suggests that hydrothermal fluid circulation may help explain deformation episodes at calderas that have not culminated in magmatic eruption.

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“…The TOUGH-FLAC simulator has been recently applied and tested over a wide range of research fields, such as carbon sequestration (e.g., Cappa and Rutqvist, 2012;Rinaldi and Rutqvist, 2013), nuclear waste disposal (e.g., Rutqvist and Tsang, 2012, and references therein), hydrothermal systems and volcanology (Todesco et al, 2004), as well as studies related to water injection in geothermal fields (e.g., Rutqvist et al, 2013a;Vasco et al, 2013).…”

Section: Model Setupmentioning

confidence: 99%

Coupled THM Modeling of Hydroshearing Stimulation in Tight Fractured Volcanic Rock

et al. 2014

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In this study, we use the TOUGH-FLAC simulator for coupled thermo-hydro-mechanical (THM) modeling of well stimulation for an Enhanced Geothermal System (EGS) project. We analyze the potential for injection-induced fracturing and reactivation of natural fractures in a porous medium with associated permeability enhancement. Our analysis aims to understand how far the EGS reservoir may grow and how the hydroshearing effect depends upon system conditions. We analyze the enhanced reservoir, or hydrosheared zone, by studying the extent of the failure zone using an elasto-plastic model, and accounting for permeability changes as a function of the induced stresses. Results, for both fully saturated and unsaturated medium cases, demonstrate how the EGS reservoir growth depends on the initial fluid phase, and how the reservoir extent changes as a function of two critical parameters: the coefficient of friction and the permeabilityenhancing factor. Moreover, whereas the stimulation is driven by the pressure exceeding a hydroshearing threshold, the modeling also demonstrates how the injection-induced cooling boosts the stimulation a bit farther.

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Modeling of recent volcanic episodes at Phlegrean Fields (Italy): geochemical variations and ground deformation

Cited by 102 publications

References 34 publications

Poroelastic responses of confined aquifers to subsurface strain and their use for volcano monitoring

Poroelastic responses of confined aquifers to subsurface strain and their use for volcano monitoring

Numerical models of caldera deformation: Effects of multiphase and multicomponent hydrothermal fluid flow

Coupled THM Modeling of Hydroshearing Stimulation in Tight Fractured Volcanic Rock

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