scholarly journals Signals from the Campi Flegrei hydrothermal system: Role of a “magmatic” source of fluids

2009 ◽  
Vol 114 (B5) ◽  
Author(s):  
Micol Todesco
Keyword(s):  
Hydrothermal System ◽  
Campi Flegrei ◽  
Magmatic Source

scholarly journals CO2 and H2S Degassing at Fangaia Mud Pool, Solfatara, Campi Flegrei (Italy): Origin and Dynamics of the Pool Basin

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1051
Author(s):  
Dmitri Rouwet ◽  
Giancarlo Tamburello ◽  
Tullio Ricci ◽  
Alessandra Sciarra ◽  
Francesco Capecchiacci ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
Co2 Flux ◽  
Campi Flegrei ◽  
Gas Migration ◽  
Campi Flegrei Caldera ◽  
Active Crater ◽  
Physical And Chemical ◽  
Solfatara Crater

The Fangaia mud pool provides a “window” into the hydrothermal system underlying the degassing Solfatara crater, which is the most active volcanic centre inside the restless Campi Flegrei caldera, Southern Italy. The present study aimed at unravelling the degassing dynamics of CO2 and H2S flushing through the pH 1.2 steam-heated Fangaia mud pool, an ideal field laboratory as a proxy of an active crater lake. Our results from MultiGAS measurements above Fangaia’s surface show that H2S scrubbing, demonstrated by high CO2/H2S ratios, was most efficient in the portions of the basin affected by diffusive degassing. Convective bubbling degassing instead was the most effective mechanism to release gas in quantitative terms, with lower CO2/H2S ratios, similar to the Solfatara crater fumaroles, the high-T end member of the hydrothermal system. Unsurprisingly, total estimated CO2 and H2S fluxes from the small Fangaia pool (~184 m2 in June 2017) were at least two orders of magnitude lower (CO2 flux < 64 t/d, H2S flux < 0.5 t/d) than the total CO2 flux of the Campi Flegrei caldera (up to 3000 t/d for CO2), too low to affect the gas budget for the caldera, and hence volcano monitoring routines. Given the role of the rising gas as “sediment stirrer”, the physical and chemical processes behind gas migration through a mud pool are arguably the creating processes giving origin to Fangaia. Follow-up studies of this so far unique campaign will help to better understand the fast dynamics of this peculiar degassing feature.

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 Geophysical and hydrogeological experiments from a shallow hydrothermal system at Solfatara Volcano, Campi Flegrei, Italy: Response to caldera unrest

2007 ◽  
Vol 112 (B6) ◽  
Author(s):  
Pier Paolo G. Bruno ◽  
Giovanni P. Ricciardi ◽  
Zaccaria Petrillo ◽  
Vincenzo Di Fiore ◽  
Antonio Troiano ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
Campi Flegrei ◽  
Caldera Unrest

scholarly journals Hydrothermal fields of the Piip submarine volcano, Komandorsky Back-Arc Basin: Chemistry and origin of vent mineralization and bubbling gas

1994 ◽  
Vol 41 ◽  
pp. 55-64
Author(s):  
Pavel V. Torokhov ◽  
Yuri A. Taran
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Isotopic Composition ◽  
Significant Role ◽  
Hydrothermal System ◽  
Submarine Volcano ◽  
Bacterial Sulphate Reduction ◽  
Back Arc ◽  
Hydrothermal Fields

Active thermal vents of the Piip submarine volcano were studied in 1990 from aboard sub­mersibles MIR 1 and 2. Samples of free gas and hydrothermal deposits were collected in the areas of thermal fluid discharge. Mineralogical, isotopic and microprobe studies of samples have shown, as the hydrothermal system cools, the high-temperature anhydrite association displayed at the surface is substituted by calcite-barite and later by calcite-barite-sulfide assemblages. The chemical and isotopic composition of gas and carbonates indicates the significant role of hydrocarbons from the sedimentary layers which, during the low-temperature stage, stimulate the processes of bacterial sulphate reduction. The evolution of a simular hydrothermal system is traced in the Great Caucasus barite deposits.

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 Repeated absolute gravity measurements on a dense network at Campi Flegrei – a reliable tool for volcano monitoring

2020 ◽  
Vol 52 ◽  
pp. 41-54
Author(s):  
Giovanna Berrino ◽  
Giuseppe Ricciardi
Keyword(s):  
Hydrothermal System ◽  
Field Measurements ◽  
Volcano Monitoring ◽  
Campi Flegrei ◽  
Absolute Gravity ◽  
Absolute Gravimeter ◽  
Time Intervals ◽  
Gravity Measurements ◽  
Gravity Network ◽  
Absolute Measurements

Abstract. Since 1981, relative gravity measurements have routinely carried out at the Campi Flegrei caldera, a densely populated area. The gravity network also includes two absolute stations periodically measured with a laboratory absolute gravimeter, which does not permit field measurements. At the end of 2014, the Osservatorio Vesuviano, Section of Napoli of the Istituto Nazionale di Geofisica e Vulcanologia (INGV-OV), acquired a portable absolute gravimeter that allows field operations on outdoor sites. Therefore, in 2015 a dense absolute gravity network was established in Campi Flegrei. This will permit an advanced approach for volcano monitoring. The net consists of 36 stations, 34 of which located inside the caldera and placed upon or very close to gravity stations belonging to the relative network. Five surveys were carried out on June 2015, on February and November 2017, on October 2018 and on October 2019. The comparison with height changes suggests that significant Δg are partly due to the uplift occurred over the same time intervals and mostly to shallow processes associated to the dynamic of the local hydrothermal system. The comparison with the gradients observed during the last large uplift (1982–1984) and the following subsidence (1985–2003) confirms this observation. These results suggest that the present activity may be due to a transient or pulsating phenomenon as the alternating recharge/discharge of fluids in the surface hydrothermal system. Gravity changes detected by absolute measurements are in good agreement with those obtained by relative ones, and confirms the feasibility of this methodology for volcano monitoring. Finally, they also encourage replacing the relative networks with absolute ones, with all the consequent advantages.

scholarly journals A roadmap for amphibious drilling at the Campi Flegrei caldera: insights from a MagellanPlus workshop

2019 ◽  
Vol 26 ◽  
pp. 29-46 ◽  
Author(s):  
Marco Sacchi ◽  
Giuseppe De Natale ◽  
Volkhard Spiess ◽  
Lena Steinmann ◽  
Valerio Acocella ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
In Situ Monitoring ◽  
Campi Flegrei ◽  
Magma Chambers ◽  
Pyroclastic Deposits ◽  
Campi Flegrei Caldera ◽  
Magma Reservoirs ◽  
Campanian Plain ◽  
International Ocean Discovery Program

Abstract. Large calderas are among the Earth's major volcanic features. They are associated with large magma reservoirs and elevated geothermal gradients. Caldera-forming eruptions result from the withdrawal and collapse of the magma chambers and produce large-volume pyroclastic deposits and later-stage deformation related to post-caldera resurgence and volcanism. Unrest episodes are not always followed by an eruption; however, every eruption is preceded by unrest. The Campi Flegrei caldera (CFc), located along the eastern Tyrrhenian coastline in southern Italy, is close to the densely populated area of Naples. It is one of the most dangerous volcanoes on Earth and represents a key example of an active, resurgent caldera. It has been traditionally interpreted as a nested caldera formed by collapses during the 100–200 km3 Campanian Ignimbrite (CI) eruption at ∼39 ka and the 40 km3 eruption of the Neapolitan Yellow Tuff (NYT) at ∼15 ka. Recent studies have suggested that the CI may instead have been fed by a fissure eruption from the Campanian Plain, north of Campi Flegrei. A MagellanPlus workshop was held in Naples, Italy, on 25–28 February 2017 to explore the potential of the CFc as target for an amphibious drilling project within the International Ocean Discovery Program (IODP) and the International Continental Drilling Program (ICDP). It was agreed that Campi Flegrei is an ideal site to investigate the mechanisms of caldera formation and associated post-caldera dynamics and to analyze the still poorly understood interplay between hydrothermal and magmatic processes. A coordinated onshore–offshore drilling strategy has been developed to reconstruct the structure and evolution of Campi Flegrei and to investigate volcanic precursors by examining (a) the succession of volcanic and hydrothermal products and related processes, (b) the inner structure of the caldera resurgence, (c) the physical, chemical, and biological characteristics of the hydrothermal system and offshore sediments, and (d) the geological expression of the phreatic and hydromagmatic eruptions, hydrothermal degassing, sedimentary structures, and other records of these phenomena. The deployment of a multiparametric in situ monitoring system at depth will enable near-real-time tracking of changes in the magma reservoir and hydrothermal system.

Upscaling laboratory measurements: Quantifying the role of hydrothermal alteration in creating geothermal and epithermal mineral resources

2020 ◽  
Author(s):  
Michael Heap ◽  
Darren Gravley ◽  
Ben Kennedy ◽  
Albert Gilg ◽  
Elisabeth Bertolett ◽  
...  
Keyword(s):  
Rock Mass ◽  
Hydrothermal Alteration ◽  
Hydrothermal System ◽  
Geothermal Energy ◽  
Laboratory Data ◽  
Mineral Resources ◽  
Low Permeability ◽  
Fluid Circulation ◽  
Porosity And Permeability

&lt;p&gt;Hydrothermal fluids can alter the chemical and physical properties of the materials through which they pass and can therefore modify the efficiency of fluid circulation. The role of hydrothermal alteration in the development of geothermal and epithermal mineral resources, systems that require the efficient hydrothermal circulation provided by fracture networks, is investigated here from a petrophysical standpoint using samples collected from a well exposed and variably altered palaeo-hydrothermal system hosted in the Ohakuri ignimbrite deposit in the Taup&amp;#333; Volcanic Zone (New Zealand). Our new laboratory data show that, although quartz and adularia precipitation reduces matrix porosity and permeability, it increases the uniaxial compressive strength, Young&amp;#8217;s modulus, and propensity for brittle behaviour. The fractures formed in highly altered rocks containing quartz and adularia are also more planar than those formed in their less altered counterparts. All of these factors combine to enhance the likelihood that a silicified rock-mass will host permeability-enhancing fractures. Indeed, the highly altered silicified rocks of the Ohakuri ignimbrite deposit are much more fractured than less altered outcrops. By contrast, smectite alteration at the margins of the hydrothermal system does not significantly increase strength or Young&amp;#8217;s modulus, or significantly decrease permeability, and creates a relatively unfractured rock-mass. Using our new laboratory data, we provide permeability modelling that shows that the equivalent permeability of a silicified rock-mass will be higher than that of a less altered rock-mass or a rock-mass characterised by smectite alteration, the latter of which provides a low-permeability cap required for an economically viable hydrothermal resource. Our new data show, using a petrophysical approach, how hydrothermal alteration can produce rock-masses that are both suitable for geothermal energy exploitation (high-permeability reservoir and low-permeability cap) and more likely to host high-grade epithermal mineral veins, such as gold and silver (localised fluid flow).&lt;/p&gt;

The role of transfer structures on volcanic activity at Campi Flegrei (Southern Italy)

1999 ◽  
Vol 91 (2-4) ◽  
pp. 123-139 ◽  
Author(s):  
V Acocella ◽  
F Salvini ◽  
R Funiciello ◽  
C Faccenna
Keyword(s):  
Volcanic Activity ◽  
Southern Italy ◽  
Campi Flegrei
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