scholarly journals Re-pressurized magma at Mt. Etna, Italy, may feed eruptions for years

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Pasquale De Gori ◽  
Elisabetta Giampiccolo ◽  
Ornella Cocina ◽  
Stefano Branca ◽  
Carlo Doglioni ◽  
...  
Keyword(s):  
Induced Seismicity ◽  
Fluid Pressure ◽  
Sharp Change ◽  
Feeding System ◽  
Seismic Wave Velocity ◽  
Internal Dynamics ◽  
Central System ◽  
Mt Etna ◽  
High Fluid ◽  
Different Depths

AbstractIdentifying and monitoring the presence of pressurized magma beneath volcanoes allows for improved understanding of internal dynamics and prediction of eruptions. Here we show with time-repeated tomography clear evidence that fresh melts accumulate since 2019 in three reservoirs located at different depths in the central feeding system. In these three volumes, we observe a significant reduction of seismic wave velocity, an anomaly that has endured for almost two years. Reservoir re-pressurization induced seismicity clusters around the pressurized volumes within high fluid pressure compartments. This indicated a sharp change in volcano behavior, with re-pressurization of the central system replacing two-decade-long, flank collapse-dominated dynamics. The volume where the velocities are altered is remarkable in size, suggesting the injection of new melt, and that erupted lava represents only a small percentage. Our findings suggest that ongoing volcanic recrudescence can persist.

scholarly journals Combining High- and Low-Rate Geodetic Data Analysis for Unveiling Rapid Magma Transfer Feeding a Sequence of Violent Summit Paroxysms at Etna in Late 2015

2021 ◽  
Vol 11 (10) ◽  
pp. 4630
Author(s):  
Alessandro Bonforte ◽  
Flavio Cannavò ◽  
Salvatore Gambino ◽  
Francesco Guglielmino
Keyword(s):  
Ground Deformation ◽  
High Rate ◽  
Rate Data ◽  
Scale Analysis ◽  
Feeding System ◽  
Magma Sources ◽  
Mt Etna ◽  
Multi Temporal ◽  
Gnss Measurements ◽  
Low Rate

We propose a multi-temporal-scale analysis of ground deformation data using both high-rate tilt and GNSS measurements and the DInSAR and daily GNSS solutions in order to investigate a sequence of four paroxysmal episodes of the Voragine crater occurring in December 2015 at Mt. Etna (Italy). The analysis aimed at inferring the magma sources feeding a sequence of very violent eruptions, in order to understand the dynamics and to image the shallow feeding system of the volcano that enabled such a rapid magma accumulation and discharge. The high-rate data allowed us to constrain the sources responsible for the fast and violent dynamics of each paroxysm, while the cumulated deformation measured by DInSAR and daily GNSS solutions, over a period of 12 days encompassing the entire eruptive sequence, also showed the deeper part of the source involved in the considered period, where magma was stored. We defined the dynamics and rates of the magma transfer, with a middle-depth storage of gas-rich magma that charges, more or less continuously, a shallower level where magma stops temporarily, accumulating pressure due to the gas exsolution. This machine-gun-like mechanism could represent a general conceptual model for similar events at Etna and at all volcanoes.

scholarly journals Emplacement and biodegradation of oil in fractured basement: the ‘coal’ deposit in Moinian gneiss at Castle Leod, Ross-shire

2016 ◽  
Vol 107 (1) ◽  
pp. 23-32 ◽  
Author(s):  
John Parnell ◽  
Mas'ud Baba ◽  
Stephen Bowden
Keyword(s):  
Lower Devonian ◽  
Fluid Pressure ◽  
Low Permeability ◽  
Coal Deposit ◽  
Basin Inversion ◽  
Mineral Phases ◽  
Metamorphic Basement ◽  
Major Fault ◽  
High Fluid ◽  
Transfer Faults

ABSTRACTBitumen veins were formerly mined as ‘coal’ from Moinian metamorphic basement at Castle Leod, Strathpeffer, Ross-shire. The abundance and spatial concentration of hydrocarbons implies generation of a large volume of oil that exerted a fluid pressure great enough to open veins to 1+ m width. Biomarker characteristics, including β-carotane and a high proportion of C28 steranes, correlate the bitumen to Lower Devonian non-marine shales separated from the Moinian basement by a major fault. Bitumen in the Moinian basement has higher diasterane/sterane ratios than bitumen in the Devonian sequence, indicating greater levels of biodegradation, which may reflect more interaction with water in the basement. Replacive bitumen nodules in the Moinian basement, containing thoriferous/uraniferous mineral phases, are comparable with bitumen nodules in basement terrains elsewhere. Formation of the nodules represents hydrocarbon penetration of low-permeability basement, consistent with high fluid pressure. Bitumen veins are particularly orientated E–W, and may be associated with E–W transfer faults attributed to Permo-Carboniferous basin inversion.

Chemical-physical constraints of the 2015 eruptive activity of Mt. Etna: new insights from thermo-barometry and geochemistry of olivine-hosted melt inclusions

2021 ◽  
Author(s):  
Pier Paolo Giacomoni ◽  
Federico Casetta ◽  
Virginia Valenti ◽  
Carmelo Ferlito ◽  
Gabriele Lanzafame ◽  
...  
Keyword(s):  
Melt Inclusions ◽  
New South ◽  
Basalt Magma ◽  
Feeding System ◽  
Physical Constraints ◽  
Eruptive Event ◽  
North East ◽  
Central Crater ◽  
Mt Etna ◽  
Crystallization Conditions

<p>The concomitant activation off all four summit craters of Mt. Etna during the December 2015 eruptive event allow us to investigate the chemical-physical crystallization conditions and magma dynamics in the shallower portion of the open-conduit feeding system. In this study, we discuss new petrological, geochemical and thermo-barometric data as well as the composition of major element and volatile content (H<sub>2</sub>O, CO<sub>2</sub>, F, Cl and S) of olivine-hosted melt inclusions from the explosive and effusive products emitted during the December 2015 eruptive event.</p><p>Results and rhyolite-MELTS thermodynamic modelling of mineral phase stability highlight the relatively shallow crystal equilibrium depth prior to the eruption ranging from 400-500 MPa for Central Crater and North East Crater, up to 200 MPa below the New South East Crater. The study of high-pressure and high-temperature homogenized olivine-hosted melt inclusions allowed us to identify the composition of the almost primary alkali-basalt magma (11.8 wt% MgO) containing up to 4.9 wt% and 8151 ppm of H<sub>2</sub>O and CO<sub>2 </sub>respectively. The results, together with those already reported for the previous paroxystic events of the 2011-2012 (Giacomoni et al., 2018), reinforce the model of a vertically extended feeding system and highlight that the activity at the New South East Crater was fed by a magma residing at significant shallower depth with respect to Central Craters and North East Crater, although all conduits are fed by a common deep (P = 530-440 MPa) basic magmatic refilling. Plagioclase stability model and dissolution and resorption textures confirm its dependence on H<sub>2</sub>O content, thus suggesting that further studies on the effect that flushing from fluids with different H<sub>2</sub>O/CO<sub>2</sub> ratio are needed in order to understand the eruption triggering mechanisms of paroxystic fountaining.</p><p> </p><p><strong>References</strong></p><p>Giacomoni P., Coltorti M., Mollo S., Ferlito C., Braiato M., Scarlato P. 2018. The 2011-2012 paroxysmal eruptions at Mt. Etna volcano: Insights on the vertically zoned plumbing system. JVGR 349, 370-391.</p>

scholarly journals Displacement across the Trecastagni Fault (Mt. Etna) and induced seismicity: the October 2009 to January 2010 episode

2011 ◽  
Vol 54 (4) ◽  
Author(s):  
Salvatore Gambino ◽  
Alessandro Bonforte ◽  
Antonino Carnazzo ◽  
Giuseppe Falzone ◽  
Ferruccio Ferrari ◽  
...  
Keyword(s):  
Induced Seismicity ◽  
Mt Etna

Mélanges and disrupted rocks at the leading edge of the Humber Arm Allochthon, W. Newfoundland Appalachians: Deformation under high fluid pressure

2019 ◽  
Vol 74 ◽  
pp. 216-236 ◽  
Author(s):  
Ryan A. Lacombe ◽  
John W.F. Waldron ◽  
S. Henry Williams ◽  
Nicholas B. Harris
Keyword(s):  
Fluid Pressure ◽  
Leading Edge ◽  
High Fluid ◽  
High Fluid Pressure

Fluid pressure response to undrained compression in saturated sedimentary rock

Geophysics ◽  
1986 ◽  
Vol 51 (4) ◽  
pp. 948-956 ◽  
Author(s):  
Douglas H. Green ◽  
Herbert F. Wang
Keyword(s):  
Pore Pressure ◽  
Effective Stress ◽  
Wave Attenuation ◽  
Fluid Pressure ◽  
Confining Pressure ◽  
Pressure Response ◽  
Additional Parameter ◽  
Seismic Wave Velocity ◽  
Specific Storage ◽  
Order Of Magnitude

The pore pressure response of saturated porous rock subjected to undrained compression at low effective stresses are investigated theoretically and experimentally. This behavior is quantified by the undrained pore pressure buildup coefficient, [Formula: see text] where [Formula: see text] is fluid pressure, [Formula: see text] is confining pressure, and [Formula: see text] is the mass of fluid per unit bulk volume. The measured values for B for three sandstones and a dolomite arc near 1.0 at zero effective stress and decrease with increasing effective stress. In one sandstone, B is 0.62 at 13 MPa effective stress. These results agree with the theories of Gassmann (1951) and Bishop (1966), which assume a locally homogeneous solid framework. The decrease of B with increasing effective stress is probably related to crack closure and to high‐compressibility materials within the rock framework. The more general theories of Biot (1955) and Brown and Korringa (1975) introduce an additional parameter, the unjacketed pore compressibility, which can be determined from induced pore pressure results. Values of B close to 1 imply that under appropriate conditions within the crust, zones of low effective pressure characterized by low seismic wave velocity and high wave attenuation could exist. Also, in confined aquifer‐reservoir systems at very low effective stress states, the calculated specific storage coefficient is an order of magnitude larger than if less overpressured conditions prevailed.

scholarly journals Fracturing and Porosity Channeling in Fluid Overpressure Zones in the Shallow Earth’s Crust

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Daniel Koehn ◽  
Sandra Piazolo ◽  
Till Sachau ◽  
Renaud Toussaint
Keyword(s):  
Effective Stress ◽  
Fluid Pressure ◽  
Mean Stress ◽  
High Porosity ◽  
Principal Stresses ◽  
Pressure Buildup ◽  
Failure Patterns ◽  
Vertical Zone ◽  
High Fluid ◽  
Fluid Overpressures

At the time of energy transition, it is important to be able to predict the effects of fluid overpressures in different geological scenarios as these can lead to the development of hydrofractures and dilating high-porosity zones. In order to develop an understanding of the complexity of the resulting effective stress fields, fracture and failure patterns, and potential fluid drainage, we study the process with a dynamic hydromechanical numerical model. The model simulates the evolution of fluid pressure buildup, fracturing, and the dynamic interaction between solid and fluid. Three different scenarios are explored: fluid pressure buildup in a sedimentary basin, in a vertical zone, and in a horizontal layer that may be partly offset by a fault. Our results show that the geometry of the area where fluid pressure is successively increased has a first-order control on the developing pattern of porosity changes, on fracturing, and on the absolute fluid pressures that sustained without failure. If the fluid overpressure develops in the whole model, the effective differential and mean stress approach zero and the vertical and horizontal effective principal stresses flip in orientation. The resulting fractures develop under high lithostatic fluid overpressure and are aligned semihorizontally, and consequently, a hydraulic breccia forms. If the area of high fluid pressure buildup is confined in a vertical zone, the effective mean stress decreases while the differential stress remains almost constant and failure takes place in extensional and shear modes at a much lower fluid overpressure. A horizontal fluid pressurized layer that is offset shows a complex system of effective stress evolution with the layer fracturing initially at the location of the offset followed by hydraulic breccia development within the layer. All simulations show a phase transition in the porosity where an initially random porosity reduces its symmetry and forms a static porosity wave with an internal dilating zone and the presence of dynamic porosity channels within this zone. Our results show that patterns of fractures, hence fluid release, that form due to high fluid overpressures can only be successfully predicted if the geometry of the geological system is known, including the fluid overpressure source and the position of seals and faults that offset source layers and seals.

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