scholarly journals Interpretation of Recent Unrest Events (Bradyseism) at Campi Flegrei, Napoli (Italy): Comparison of Models Based on Cyclical Hydrothermal Events versus Shallow Magmatic Intrusive Events

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
A. Lima ◽  
R. J. Bodnar ◽  
B. De Vivo ◽  
F. J. Spera ◽  
H. E. Belkin
Keyword(s):  
Hydrothermal System ◽  
Fluid Pressure ◽  
Hydrothermal Activity ◽  
Temporal Variations ◽  
Geological Structure ◽  
Campi Flegrei ◽  
Pressure Gradients ◽  
Silica Precipitation ◽  
Eruption Precursors ◽  
Upper Aquifer

Several recent models that have been put forth to explain bradyseism at Campi Flegrei (CF), Italy, are discussed. Data obtained during long-term monitoring of the CF volcanic district has led to the development of a model based on lithological-structural and stratigraphic features that produce anisotropic and heterogeneous permeability features showing large variations both horizontally and vertically; these data are inconsistent with a model in which bradyseism is driven exclusively by shallow magmatic intrusions. CF bradyseism events are driven by cyclical magmatic-hydrothermal activity. Bradyseism events are characterized by cyclical, constant invariant signals repeating over time, such as area deformation along with a spatially well-defined seismogenic volume. These similarities have been defined as “bradyseism signatures” that allow us to relate the bradyseism with impending eruption precursors. Bradyseism is governed by an impermeable shallow layer (B-layer), which is the cap of an anticlinal geological structure culminating at Pozzuoli, where maximum uplift is recorded. This B-layer acts as a throttling valve between the upper aquifer and the deeper hydrothermal system that experiences short (1-102 yr) timescale fluctuations between lithostatic/hydrostatic pressure. The hydrothermal system also communicates episodically with a cooling and quasi-steady-state long timescale (103-104 yr) magmatic system enclosed by an impermeable carapace (A layer). Connectivity between hydrostatic and lithostatic reservoirs is episodically turned on and off causing alternatively subsidence (when the systems are connected) or uplift (when the systems are disconnected), depending on whether permeability by fractures is established or not. Earthquake swarms are the manifestation of hydrofracturing which allows fluid expansion; this same process promotes silica precipitation that seals cracks and serves to isolate the two reservoirs. Faults and fractures promote outgassing and reduce the vertical uplift rate depending on fluid pressure gradients and spatial and temporal variations in the permeability field. The miniuplift episodes also show “bradyseism signatures” and are well explained in the context of the short timescale process.

scholarly journals Temperature and pressure gas geoindicators at the Solfatara fumaroles (Campi Flegrei)

2011 ◽  
Vol 54 (2) ◽  
Author(s):  
Giovanni Chiodini ◽  
Rosario Avino ◽  
Stefano Caliro ◽  
Carmine Minopoli
Keyword(s):  
Hydrothermal System ◽  
Fluid Pressure ◽  
Critical Conditions ◽  
Campi Flegrei ◽  
Gas System ◽  
Show Evidence ◽  
Long Time ◽  
Compositional Variations ◽  
Pressure Changes ◽  
Solfatara Crater

Long time series of fluid pressure and temperature within a hydrothermal system feeding the Solfatara fumaroles are investigated here, on the basis of the chemical equilibria within the CO2&ndash;H2O&ndash;H2&ndash;CO gas system. The Pisciarelli fumarole external to Solfatara crater shows an annual cycle of CO contents that indicates the occurrence of shallow secondary processes that mask the deep signals. In contrast, the Bocca Grande and Bocca Nova fumaroles located inside Solfatara crater do not show evidence of secondary processes, and their compositional variations are linked to the temperature&ndash;pressure changes within the hydrothermal system. The agreement between geochemical signals and the ground movements of the area (bradyseismic phenomena) suggests a direct relationship between the pressurization process and the ground uplift. Since 2007, the gas geoindicators have indicated pressurization of the system, which is most probably caused by the arrival of deep gases with high CO2 contents in the shallow parts of the hydrothermal system. This pressurization process causes critical conditions in the hydrothermal system, as highlighted by the increase in the fumarole temperature, the opening of new vents, and the localized seismic activity. If the pressurization process continues with time, it is not possible to rule out the occurrence of phreatic explosions.<br />

Intraventricular injection of antibodies to β1-integrins generates pressure gradients in the brain favoring hydrocephalus development in rats

2009 ◽  
Vol 297 (5) ◽  
pp. R1312-R1321 ◽  
Author(s):  
Gurjit Nagra ◽  
Lena Koh ◽  
Isabelle Aubert ◽  
Minhui Kim ◽  
Miles Johnston
Keyword(s):  
Fluid Pressure ◽  
Active Role ◽  
Intraventricular Injection ◽  
Pressure Gradients ◽  
Tissue Pressure ◽  
Before And After ◽  
The Matrix ◽  
System 2 ◽  
Periventricular Area ◽  
The Brain

In some tissues, the injection of antibodies to the β1-integrins leads to a reduction in interstitial fluid pressure, indicating an active role for the extracellular matrix in tissue pressure regulation. If perturbations of the matrix occur in the periventricular area of the brain, a comparable lowering of interstitial pressures may induce transparenchymal pressure gradients favoring ventricular expansion. To examine this concept, we measured periventricular (parenchymal) and ventricular pressures with a servo-null micropipette system (2-μm tip) in adult Wistar rats before and after anti-integrin antibodies or IgG/IgM isotype controls were injected into a lateral ventricle. In a second group, the animals were kept for 2 wk after similar injections and after euthanization, the brains were removed and assessed for hydrocephalus. In experiments in which antibodies to β1-integrins ( n = 10) but not isotype control IgG/IgM ( n = 7) were injected, we observed a decline in periventricular pressures relative to the preinjection values. Under similar circumstances, ventricular pressures were elevated ( n = 10) and were significantly greater than those in the periventricular interstitium. We estimated ventricular to periventricular pressure gradients of up to 4.3 cmH2O. In the chronic preparations, we observed enlarged ventricles in many of the animals that received injections of anti-integrin antibodies (21 of 29 animals; 72%) but not in any animal receiving the isotype controls. We conclude that modulation/disruption of β1-integrin-matrix interactions in the brain generates pressure gradients favoring ventricular expansion, suggesting a novel mechanism for hydrocephalus development.

scholarly journals Development and analytical validation of a finite element model of fluid transport through osteochondral tissue

2020 ◽  
Author(s):  
Brady D. Hislop ◽  
Chelsea M. Heveran ◽  
Ronald K. June
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Fluid Transport ◽  
Fluid Pressure ◽  
Viscoelastic Model ◽  
Element Model ◽  
Pressure Gradients ◽  
Superficial Zone ◽  
Bone Interface ◽  
Osteochondral Tissue

AbstractFluid transport between cartilage and bone is critical to joint health. The objective of this study was to develop and analytically validate a finite element model of osteochondral tissue capable of modeling cartilage-bone fluid transport. A biphasic viscoelastic model using an ellipsoidal fiber distribution was created with three distinct layers of cartilage (superficial zone, middle zone, and deep zone) along with a layer of subchondral bone. For stress-relaxation in unconfined compression, our results for compressive stress, radial stress, effective fluid pressure, and elastic recoil were compared with established biphasic analytical solutions. Our model also shows the development of fluid pressure gradients at the cartilage-bone interface during loading. Fluid pressure gradients developed at the cartilage-bone interface with consistently higher pressures in cartilage following initial loading to 10% strain, followed by convergence towards equal pressures in cartilage and bone during the 400s relaxation period. These results provide additional evidence that fluid is transported between cartilage and bone during loading and improves upon estimates of the magnitude of this effect through incorporating a realistic distribution and estimate of the collagen ultrastructure. Understanding fluid transport between cartilage and bone may be key to new insights about the mechanical and biological environment of both tissues in health and disease.

scholarly journals Modelling ground displacement and gravity changes with the MUFITS simulator

2020 ◽  
Vol 54 ◽  
pp. 89-98
Author(s):  
Andrey Afanasyev ◽  
Ivan Utkin
Keyword(s):  
Scientific Community ◽  
Hydrothermal Activity ◽  
Campi Flegrei ◽  
Ground Displacement ◽  
Benchmark Study ◽  
Comprehensive Method ◽  
Gravity Changes ◽  
Subsurface Flows ◽  
Reservoir Simulator ◽  
First Time

Abstract. We present an extension of the MUFITS reservoir simulator for modelling the ground displacement and gravity changes associated with subsurface flows in geologic porous media. Two different methods are implemented for modelling the ground displacement. The first approach is simple and fast and is based on an analytical solution for the extension source in a semi-infinite elastic medium. Its application is limited to homogeneous reservoirs with a flat Earth surface. The second, more comprehensive method involves a one-way coupling of MUFITS with geomechanical code presented for the first time in this paper. We validate the accuracy of the development by considering a benchmark study of hydrothermal activity at Campi Flegrei (Italy). We investigate the limitations of the first approach by considering domains for the geomechanical problem that are larger than those for the fluid flow. Furthermore, we present the results of more complicated simulations in a heterogeneous subsurface when the assumptions of the first approach are violated. We supplement the study with the executable of the simulator for further use by the scientific community.

Geochemical evidence of volcanic plumbing system processes from fumarolic gases and diffuse CO2 degassing of Taal volcano, Philippines, prior to the January 2020 eruption 

2021 ◽  
Author(s):  
Pedro A. Hernández ◽  
Gladys Melian ◽  
María Asensio-Ramos ◽  
Eleazar Padron ◽  
Hirochicka Sumino ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
Temporal Variations ◽  
Average Value ◽  
Taal Volcano ◽  
Magmatic Intrusion ◽  
Volcanic Plumbing System ◽  
Wide Range ◽  
Fumarolic Gases ◽  
Co2 Degassing ◽  
Increasing Trends

&lt;p&gt;Significant temporal variations in the chemical and isotopic composition of Taal fumarolic gas as well as in diffuse CO&lt;sub&gt;2&lt;/sub&gt; emission from Taal Main Crater Lake (TMLC) have been observed across the ~12 years of geochemical monitoring (Arpa et al., 2013; Hern&amp;#225;ndez et a., 2017), with significant high CO&lt;sub&gt;2 &lt;/sub&gt;degassing rates, typical of plume degassing volcanoes, measured in 2011 and 2017. In addition to these CO&lt;sub&gt;2&lt;/sub&gt; surveys at the TCML, soil CO&lt;sub&gt;2&lt;/sub&gt; efflux continuous monitoring was implemented at Taal volcano since 2016 and a clear increasing trend of the soil CO&lt;sub&gt;2&lt;/sub&gt; efflux in 2017 was also observed. Increasing trends on the fumarolic CO&lt;sub&gt;2&lt;/sub&gt;/St, He/CO&lt;sub&gt;2&lt;/sub&gt;, CO/CO&lt;sub&gt;2&lt;/sub&gt; and CO&lt;sub&gt;2&lt;/sub&gt;/CH&lt;sub&gt;4&lt;/sub&gt; ratios were recorded during the period 2010-2011 whereas increasing SO&lt;sub&gt;2&lt;/sub&gt;/H&lt;sub&gt;2&lt;/sub&gt;S, H&lt;sub&gt;2&lt;/sub&gt;/CO&lt;sub&gt;2&lt;/sub&gt; ratios were recorded during the period 2017-2018. A decreasing on the CO&lt;sub&gt;2&lt;/sub&gt;/CH&lt;sub&gt;4&lt;/sub&gt; and CO&lt;sub&gt;2&lt;/sub&gt;/St ratios was observed for 2017-2018. These changes are attributed to an increased contribution of magmatic fluids to the hydrothermal system in both periods. Observed changes in H&lt;sub&gt;2&lt;/sub&gt; and CO contents suggest increases in temperature and pressure in the upper parts of the hydrothermal system of Taal volcano. The &lt;sup&gt;3&lt;/sup&gt;He/&lt;sup&gt;4&lt;/sup&gt;He ratios corrected (Rc/Ra), and &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C of fumarolic gases also increased during the periods 2010-2011 and 2017-2018 before the eruption onset. During this study, diffuse CO&lt;sub&gt;2&lt;/sub&gt; emission values measured at TMCL showed a wide range of values from &gt;0.5&amp;#8201;g&amp;#8201;m&lt;sup&gt;&amp;#8722;2&lt;/sup&gt; d&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; up to 84,902 g&amp;#8201;m&lt;sup&gt;&amp;#8722;2&lt;/sup&gt; d&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;. The observed relatively high and anomalous diffuse CO&lt;sub&gt;2&lt;/sub&gt; emission rate across the ~12 years reached values of 4,670 &amp;#177; 159 t d&lt;sup&gt;-1 &lt;/sup&gt;on March 24, 2011, and 3,858 &amp;#177; 584 t d&lt;sup&gt;-1&lt;/sup&gt; on November 11, 2017. The average value of the soil CO&lt;sub&gt;2&lt;/sub&gt; efflux data measured by the geochemical station showed oscillations around background values until 14 March, 2017. Since then at 22:00 hours, a sharp increase of soil CO&lt;sub&gt;2&lt;/sub&gt; efflux from ~0.1 up to 1.1 kg m&lt;sup&gt;-2&lt;/sup&gt; d&lt;sup&gt;-1&lt;/sup&gt; was measured in 9 hours and continued to show a sustained increase in time up to 2.9 kg m&lt;sup&gt;-2&lt;/sup&gt; d&lt;sup&gt;-1&lt;/sup&gt; in 2 November, that represents the main long-term variation of the soil CO&lt;sub&gt;2&lt;/sub&gt; emission time series. All the above variations might be produced by two episodes of magmatic intrusion which favored degassing of a gas-rich magma at depth. During the 2010-2011 the magmatic intrusion of volatile-rich magma might have occurred from the mid-crustal storage region at shallower depths producing important changes in pressure and temperature conditions, whereas a new injection of more degassed magma into the deepest zone of the hydrothermal system occurring in 2017-2018 might have favored the accumulation of gases in the subsurface, promoting conditions leading to a phreatic eruption. These geochemical observations are most simply explained by magma recharge to the system, and represent the earliest warning precursor signals to the January 2020 eruptive activity.&lt;/p&gt;&lt;p&gt;Arpa, M.C., et al., 2013. Bull. Volcanol. 75, 747. https://doi.org/10.1007/s00445-013-0747-9.&lt;/p&gt;&lt;p&gt;Hern&amp;#225;ndez, P.A., et al.,&amp;#160; 2017. Geol. Soc. Lond. Spec. Publ. 437:131&amp;#8211;152. https://doi.org/10.1144/SP437.17.&lt;/p&gt;

Trade-offs between deep (magmatic) and shallow (hydrological) forcings on volcanic unrest at La Soufrière de Guadeloupe (Lesser Antilles)

2021 ◽  
Author(s):  
David Jessop ◽  
Roberto Moretti ◽  
Séverine Moune ◽  
Vincent Robert
Keyword(s):  
Time Series ◽  
Hydrothermal System ◽  
Temporal Variations ◽  
Temperature Record ◽  
Trade Offs ◽  
External Forcings ◽  
Seismic Swarms ◽  
Long Time ◽  
Deep Activity

&lt;p&gt;Fumarolic gas composition and temperature record deep processes that generate and transfer heat and mass towards the surface. &amp;#160;These processes are a result of the emplacement, degassing and cooling of magma and the overturning of the above hydrothermal system. &amp;#160;A reasonable expectation, and too often an unproved assumption, is that fumarole temperatures and the deep heat sources vary on similar timescales. &amp;#160;Yet signals from deep and shallow processes have vastly different temporal variations.&amp;#160; This indicates that signals arising from deep activity may be masked or modified by intervening hydrothermal processes, such as fluid-groundrock reactions in which secondary minerals play a major role. &amp;#160;Clearly, this complicates the interpretation of the signals such as the joint variation of fumarole vent temperature and geochemical ratios in terms of what is occurring at depth. &amp;#160;So what do the differences between the timescales governing deep and shallow processes tell us about the intervening transport mechanisms?&lt;/p&gt;&lt;p&gt;At the volcanic dome of La Soufri&amp;#232;re de Guadeloupe, the Observatoire Volcanologique et Sismologique de la Guadeloupe has performed weekly-to-monthly in-situ vent gas sampling over many years. &amp;#160;These analyses reliably track several geochemical species ratios over time, which provide important information about the evolution of deep processes. &amp;#160;Vent temperature is measured as part of the in-situ sampling, giving a long time series of these measurements. &amp;#160;Here, we look to exploit the temporal variations in these data to establish the common processes, and also to determine why these signals differ. &amp;#160;By fitting sinusoids to the gas-ratio time series we find that several of the deep signals are strongly sinusoidal. &amp;#160;For example, the He/CH&lt;sub&gt;4&lt;/sub&gt; and CO&lt;sub&gt;2&lt;/sub&gt;/CH&lt;sub&gt;4&lt;/sub&gt; ratios, which involve conservative components and mark the injection of deep and hot magmatic fluids, oscillate on a timescale close to 3 years. We also analyse the frequency content of the temperature measurements since 2011 and find that such long signals are not seen. &amp;#160;This may be due to internal buffering by the hydrothermal system, but other external forcings are also present. &amp;#160;From these data we build up a more informed model of the heat-and-mass supply chain from depth to the surface. &amp;#160;This will potentially allow us to predict future unrest (e.g. thermal crises, seismic swarms), and distinguish between sources of unrest.&lt;/p&gt;

scholarly journals Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of a restless caldera

Solid Earth ◽  
2016 ◽  
Vol 7 (2) ◽  
pp. 557-577 ◽  
Author(s):  
A. Coco ◽  
J. Gottsmann ◽  
F. Whitaker ◽  
A. Rust ◽  
G. Currenti ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Pore Pressure ◽  
Hydrothermal System ◽  
Ground Deformation ◽  
Numerical Models ◽  
Gravity Data ◽  
Ground Surface ◽  
Campi Flegrei ◽  
Hazard Evaluation ◽  
Gravity Changes

Abstract. Ground deformation and gravity changes in restless calderas during periods of unrest can signal an impending eruption and thus must be correctly interpreted for hazard evaluation. It is critical to differentiate variation of geophysical observables related to volume and pressure changes induced by magma migration from shallow hydrothermal activity associated with hot fluids of magmatic origin rising from depth. In this paper we present a numerical model to evaluate the thermo-poroelastic response of the hydrothermal system in a caldera setting by simulating pore pressure and thermal expansion associated with deep injection of hot fluids (water and carbon dioxide). Hydrothermal fluid circulation is simulated using TOUGH2, a multicomponent multiphase simulator of fluid flows in porous media. Changes in pore pressure and temperature are then evaluated and fed into a thermo-poroelastic model (one-way coupling), which is based on a finite-difference numerical method designed for axi-symmetric problems in unbounded domains.Informed by constraints available for the Campi Flegrei caldera (Italy), a series of simulations assess the influence of fluid injection rates and mechanical properties on the hydrothermal system, uplift and gravity. Heterogeneities in hydrological and mechanical properties associated with the presence of ring faults are a key determinant of the fluid flow pattern and consequently the geophysical observables. Peaks (in absolute value) of uplift and gravity change profiles computed at the ground surface are located close to injection points (namely at the centre of the model and fault areas). Temporal evolution of the ground deformation indicates that the contribution of thermal effects to the total uplift is almost negligible with respect to the pore pressure contribution during the first years of the unrest, but increases in time and becomes dominant after a long period of the simulation. After a transient increase over the first years of unrest, gravity changes become negative and decrease monotonically towards a steady-state value.Since the physics of the investigated hydrothermal system is similar to any fluid-filled reservoir, such as oil fields or CO2 reservoirs produced by sequestration, the generic formulation of the model will allow it to be employed in monitoring and interpretation of deformation and gravity data associated with other geophysical hazards that pose a risk to human activity.

scholarly journals Shallow Magmatic Hydrothermal Eruption in April 2018 on Ebinokogen Ioyama Volcano in Kirishima Volcano Group, Kyushu, Japan

Geosciences ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 183 ◽  
Author(s):  
Yasuhisa Tajima ◽  
Setsuya Nakada ◽  
Fukashi Maeno ◽  
Toshio Huruzono ◽  
Masaaki Takahashi ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
Hydrothermal Activity ◽  
Volcanic Field ◽  
Multiple Systems ◽  
Geothermal Activity ◽  
Hydrothermal Eruption ◽  
Kirishima Volcano ◽  
Geophysical Observation ◽  
Under The Volcano ◽  
Fluid Pressurization

The Kirishima Volcano Group is a volcanic field ideal for studying the mechanism of steam-driven eruptions because many eruptions of this type occurred in the historical era and geophysical observation networks have been installed in this volcano. We made regular geothermal observations to understand the hydrothermal activity in Ebinokogen Ioyama Volcano. Geothermal activity resumed around the Ioyama from December 2015. A steam blowout occurred in April 2017, and a hydrothermal eruption occurred in April 2018. Geothermal activity had gradually increased before these events, suggesting intrusion of the magmatic component fluids in the hydrothermal system under the volcano. The April 2018 eruption was a magmatic hydrothermal eruption caused by the injection of magmatic fluids into a very-shallow hydrothermal system as a bottom–up fluid pressurization, although juvenile materials were not identifiable. Additionally, the upwelling of mixed magma–meteoric fluids to the surface as a kick was observed just before the eruption to cause the top–down flashing of April 2018. A series of events was generated in the shallower hydrothermal regime consisting of multiple systems divided by conductive caprock layers.

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