Permeable convection above magma bodies

Hardee, H.C.

doi:10.1016/0040-1951(82)90159-7

Cited by 52 publications

(36 citation statements)

References 18 publications

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“…The current caldera shape is the result of two collapses related to the Campanian Ignimbrite eruption (CI; 150-200 km 3 dense rock equivalent (DRE); age, 39 ky BP) and possibly to a minor subsidence associated with the Neapolitan Yellow Tuff eruption (NYT; 40 km 3 DRE; age, 12-15.6 ky BP) [21][22][23][24][25]. The caldera is underlain by a primary zone of magma storage that is 1.2 km to 1.5 km thick, and which has a top at about 7.5 km below the surface [26]; there is also a quenched relict of an ancient magma source at a depth of about 4 km [9,16,17], which has possibly been intruded into by new magma during recent unrests [9,16,17].…”

Section: Geological Setting and Heat Dischargementioning

confidence: 99%

“…Quiescent and active volcanism is almost always accompanied by heat and fluid output [1], and thus, thermal data are essential to assess the amount of energy being released and the mass transport within the shallow crust [2,3]. The thermal state of volcanoes and the temperature records are also important in correlating the areas of higher heat discharge with the main tectonics and structural features of volcanic edifices.…”

Section: Introductionmentioning

confidence: 99%

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Distributed-Temperature-Sensing Using Optical Methods: A First Application in the Offshore Area of Campi Flegrei Caldera (Southern Italy) for Volcano Monitoring

Carlino

Mirabile²,

Troise

et al. 2016

Remote Sensing

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Abstract:A temperature profile 2400 m along the off-shore active caldera of Campi Flegrei (Gulf of Pozzuoli) was obtained by the installation of a permanent fiber-optic monitoring system within the framework of the Innovative Monitoring for Coastal and Marine Environment (MON.I.C.A) project. The system consists of a submerged, reinforced, multi-fiber cable containing six single-mode telecom grade optical fibers that, exploiting the stimulated Brillouin scattering, provide distributed temperature sensing (DTS) with 1 m of spatial resolution. The obtained data show that the offshore caldera, at least along the monitored profile, has many points of heat discharge associated with fluid emission. A loose association between the temperature profile and the main structural features of the offshore caldera was also evidenced by comparing DTS data with a high-resolution reflection seismic survey. This represents an important advancement in the monitoring of this high-risk volcanic area, since temperature variations are among the precursors of magma migration towards the surface and are also crucial data in the study of caldera dynamics. The adopted system can also be applied to many other calderas which are often partially or largely submerged and hence difficult to monitor.

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Section: Geological Setting and Heat Dischargementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Distributed-Temperature-Sensing Using Optical Methods: A First Application in the Offshore Area of Campi Flegrei Caldera (Southern Italy) for Volcano Monitoring

Carlino

Mirabile²,

Troise

et al. 2016

Remote Sensing

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“…Faults and fractures, in particular, control the permeability of the rock masses according to Darcy's cubic law (Caine et al, 1996;Faulkner et al, 2010), whereas the permeability of soils relates to the grain-size distribution as well as compaction, cementation and alteration (Shepherd, 1989;Benson et al, 1995); consequently they all accomplish convective heat flow (Hardee, 1982). Variations in volcanic and geothermal activity have been frequently observed at sites such as Vulcano Island, Italy (Bukumirovic et al, 1997;Harris and Maciejewski, 2000), at Iwodake Volcano, Japan (Matsushima et al, 2003), at the Solfatara of Pozzuoli, Italy (Chiodini et al, 2007), and at Colima, Mexico (Stevenson and Varley;, but they were alternatively attributed to changes in the magmatic or hydrothermal source (Stevenson, 1993), to permeability changes due to conduit sealing by deposition or tectonic activity (Harris and Maciejewski, 2000), or a combination thereof.…”

Section: Introductionmentioning

confidence: 99%

The ring-shaped thermal field of Stefanos crater, Nisyros Island: a conceptual model

Pantaleo

Walter

2014

Solid Earth

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Abstract. Fumarole fields related to hydrothermal processes release the heat of the underground through permeable pathways. Thermal changes, therefore, are likely to depend also on the size and permeability variation of these pathways. There may be different explanations for the observed permeability changes, such as fault control, lithology, weathering/alteration, heterogeneous sediment accumulation/erosion and physical changes of the fluids (e.g., temperature and viscosity). A common difficulty, however, in surface temperature field studies at active volcanoes is that the parameters controlling the ascending routes of fluids are poorly constrained in general. Here we analyze the crater of Stefanos, Nisyros (Greece), and highlight complexities in the spatial pattern of the fumarole field related to permeability conditions. We combine high-resolution infrared mosaics and grain-size analysis of soils, aiming to elaborate parameters controlling the appearance of the fumarole field. We find a ring-shaped thermal field located within the explosion crater, which we interpret to reflect near-surface contrasts of the soil granulometry and volcanotectonic history at depth. We develop a conceptual model of how the ring-shaped thermal field formed at the Stefanos crater and similarly at other volcanic edifices, highlighting the importance of local permeability contrast that may increase or decrease the thermal fluid flux.

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“…This phenomenon is well studied and the influence of capillarity effects has been elaborated [McGuinness, 1996]. Such flows are called "heat pipes" and can transfer heat in excess of that by conduction alone [Hardee, 1982]. It is worth noting that the effectiveness of such flows (e.g., ratio of convective and conductive heat fluxes at given boundary temperatures) is higher than that of convection without phase transitions.…”

Section: Introductionmentioning

confidence: 99%

“…Porous convection of the liquid and gaseous water mixture in hydrothermal systems can operate in the form of one-dimensional phase settling flow [Hardee, 1982]. Liquid in equilibrium with the gas phase has a higher density and permanently moves downward while gas rises.…”

Section: Introductionmentioning

confidence: 99%

Salt loaded heat pipes: steady-state operation and related heat and mass transport

Simakin¹,

Ghassemi²

2003

Earth and Planetary Science Letters

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There is evidence suggesting that fluids in the root zone of many hydrothermal systems (at the brittle-ductile transition zone, about 3-4 km) can be highly saline. Therefore, fluid (state) can be expected to be in subcritical conditions and intensive multiphase convection may occur at those depths. The particular type of fluid-solid interaction and as well as the fluid state depends on the fluid and rock compositions. This can be rather complicated involving several liquid and gaseous phases. As the simplest illustrative example, we consider the NaCl-H 2 O system assuming the rock matrix to be chemically inert. When limited to three phases (NaCl-L-V), the critical curves and the pressures of the liquid-gas equilibrium in the system seem to be too low when compared with expected parameters of the root zone of the geothermal systems (T=380-450 o C). The fluid pressure is not well constrained and can be lower than hydrostatic due to active deformations that can increase rock porosity (fracture).In this work we examine the model for a onedimensional steady-state, two-phase gravity flow. The work involves derivation of the steady-state solution for mass balance equations for all components and fluid flow equations for the gas and liquid phases. Results show that in a three phase set (salt-water-gas), the plot of the steady-state liquid volume fraction, ε, vs. liquid temperature in the convecting column bifurcates into two sets of closed curves. Separation occurs because the maximum of the P 3b (T) curve divides the entire P-ε plane into domains of solution-like and hydrous NaCl melt liquid phases. For the salt-unsaturated two-phase equilibrium, dependence of the steady-state liquid volume fraction describes a folded surface in the P-T-ε space. An estimate of the upper level of heat flux that can be transported through the salt loaded heat pipe yields a maximum of 10-15 W/m 2 at a permeability coefficient value, k, of about 10 -15 m 2 . Due to difference in the solubility of salt (or silicate materials) in the liquid and gas phases, heat transfer in salt loaded heat pipes is intrinsically connected to mass transfer. We suggest that the multi-phase convection of aggressive brines at high P-T can cause deep karst in the zone of dissolution. This process can be facilitated by hydrolysis with the acid that separates as a gaseous phase upon boiling. Assuming a solubility level of about 10 wt % and a permeability of 10 -15 m 2 yields a net dissolution rate of 2-3 cm/yr. This is close to the subsidence rates measured in some geothermal fields. Mechanical deformation in the system may also play an important role in developing fluid pathways through continuously sealed areas separating geothermal fluid reservoirs in the brittle and ductile zones.

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Permeable convection above magma bodies

Cited by 52 publications

References 18 publications

Distributed-Temperature-Sensing Using Optical Methods: A First Application in the Offshore Area of Campi Flegrei Caldera (Southern Italy) for Volcano Monitoring

Distributed-Temperature-Sensing Using Optical Methods: A First Application in the Offshore Area of Campi Flegrei Caldera (Southern Italy) for Volcano Monitoring

The ring-shaped thermal field of Stefanos crater, Nisyros Island: a conceptual model

Salt loaded heat pipes: steady-state operation and related heat and mass transport

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