Groundwater flow and fluid/groundwater geochemical characterization at Ischia Island: a new strategy for the mitigation of the volcanic risk

2020 ◽  
Author(s):  
Sandro de Vita ◽  
Mauro A. Di Vito ◽  
Enrica Marotta ◽  
Rosario Avino ◽  
Antonio Carandente ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
Hydrothermal Systems ◽  
Civil Defense ◽  
Thermal Springs ◽  
Volcanic Risk ◽  
Volcanic System ◽  
Geochemical Characterization ◽  
Tectonic Processes ◽  
Hydrogeological Information ◽  
Island Of Ischia

<p>The volcanic system of Ischia is characterized by an intense hydrothermal activity, documented since the early 16th century by the study of Iasolino (1588), which represents the first systematic analysis of the thermal springs of the island for therapeutic purposes. Later studies partially contributed to the enhancement of knowledge on the volcanic, hydrogeological and hydrothermal features of the island, highlighting the strong interaction between hydrothermal flowpaths and volcano-tectonic processes . The reconstruction of the hydrothermal system becomes, therefore, a fundamental element for territorial planning, not only in terms of management of the huge water and geothermal resource, but also and above all in a perspective of prevention and mitigation of volcanic risk. Thermal springs, fumaroles and clay deposits due to the hydrothermal alteration of volcanic products testifies for the existence of an active deep hydrothermal system. Commonly, the geochemical characterization of fluids and groundwater has been used for the definition of the origin and structure of hydrothermal systems, when hydrogeological information is incomplete. However, volcanic hydrothermal systems, such as that characterizes the island of Ischia, are particularly difficult to analyze and outline, as the groundwater resources are the result of an articulated and dynamic interaction among meteoric water, sea water and fluids of deep origin. In such cases, the need for an interdisciplinary approach is evident, involving knowledge and research methods ranging from geology to volcanology, geophysics, geochemistry and hydrogeology. With particular reference to the functional and structural representation of the geothermal system of the island of Ischia and the resulting correlations with the volcano-tectonic processes, the examination of previous information highlights the need to update and improve the knowledge on groundwater hydrodynamics and mineralization processes.</p><p>Therefore, this study represents the result of  a strong interdisciplinary action that, starting from the design and implementation of a database on the existing geological/volcanological and hydrogeological information, contributes to highlight the critical issues, defines an operating scheme of the hydro-geo-thermal system of the island of Ischia, and aims at upgrade its hydrogeological, geochemical and volcanic monitoring system, in order to contribute to the mitigation of natural risks.</p><p>Moreover, this study well fits into the framework of the ongoing researches on volcanic hazard at Ischia and is integrated with the actions planned by the Italian Department of Civil Defense. The knowledge of groundwater dynamics and pathways is of fundamental importance for understanding the water/magma interaction processes in case of re-alimentation of the shallow magmatic system, and the assessment of the possibility of phreatic explosions occurrence.</p><p> </p>

scholarly journals Response of a Hydrothermal System to Escalating Phreatic Unrest the Case of Turrialba and Irazú in Costa Rica (2007-2012)

2021 ◽  
Author(s):  
Dmitri Rouwet ◽  
Raul Mora-Amador ◽  
Carlos Ramirez ◽  
Gino González-Ilama ◽  
Eleonora Baldoni ◽  
...  
Keyword(s):  
Costa Rica ◽  
Hydrothermal System ◽  
Crater Lake ◽  
Removal Rate ◽  
Summit Crater ◽  
Hydrothermal Systems ◽  
Thermal Springs ◽  
Total Output ◽  
Crater Lakes ◽  
Phreatic Eruptions

Abstract This study presents the first hydrogeochemical model of the hydrothermal systems of Turrialba and Irazú volcanoes in central Costa Rica, manifested as thermal springs, summit crater lakes, and fumarolic degassing at both volcanoes. Our period of observations (2007-2012) coincides with the pre- and early syn-phreatic eruption stages of Turrialba volcano that resumed volcanic unrest since 2004, after almost 140 years of quiescence. Peculiarly, the generally stable Irazú crater lake dropped its level during this reawakening of Turrialba. The isotopic composition of discharged fluids reveals the Caribbean meteoric origin; a contribution of “andesitic water” for Turrialba fumaroles up to ~50% is suggested. Four groups of thermal springs drain the northern flanks of Turrialba and Irazú volcanoes into two main rivers. Río Sucio (i.e. “dirty river”) is a major rock remover on the North flank of Irazú, mainly fed by the San Cayetano spring group. Instead, one group of thermal springs discharges towards the south of Irazú. All thermal spring waters are of SO4-type (i.e. steam heated waters), although none of the springs has a common hydrothermal end-member. A water mass budget for thermal springs results in an estimated total output flux of 187 ± 37 L/s, with 100 ± 20 L/s accounted for by the San Cayetano springs. Thermal energy release is estimated at 110 ± 22 MW (83.9 ± 16.8 MW by San Cayetano), whereas the total rock mass removal rate by chemical leaching is ~3,000 m3/y (~2,400 m3/y by San Cayetano-Río Sucio). Despite Irazú being the currently less active volcano, it is a highly efficient rock remover, which, on the long term can have effects on the stability of the volcanic edifice with potentially hazardous consequences (e.g. flank collapse, phreatic eruptions). Moreover, the vapor output flux from the Turrialba fumaroles after the onset of phreatic eruptions on 5 January 2010 showed an increase of at least ~260 L/s above pre-eruptive background fumarolic vapor fluxes. This extra vapor loss implies that the drying of the summit hydrothermal system of Turrialba could tap deeper than previously thought, and could explain the coincidental disappearance of Irazú’s crater lake in April 2010.

3-D Geoelectrical Characterisation of the Central Volcanoes of São Miguel Island (Azores Archipelago, Portugal) using Broad-Band Magnetotelluric Data

2020 ◽  
Author(s):  
Duygu Kiyan ◽  
Colin Hogg ◽  
Volker Rath ◽  
Andreas Junge ◽  
Rita Carmo ◽  
...  
Keyword(s):  
Fracture Zone ◽  
Hydrothermal System ◽  
High Frequency ◽  
Broad Band ◽  
Hydrothermal Systems ◽  
Volcanic System ◽  
Magnetotelluric Soundings ◽  
Field Campaign ◽  
The North ◽  
Swarm Activity

<p>The Azores islands are located at the triple junction between the North American, Eurasian and African plates. The Mid-Atlantic Ridge separates the North America from Eurasia and African plates, while Azores-Gibraltar Fracture Zone is the boundary between Eurasia and African plates. São Miguel Island, situated at the southeastern part of the western segment of the Azores-Gibraltar Fracture Zone, has three active strato-volcanoes, Sete Cidades, Fogo (Água de Pau), and Furnas. At Furnas and Fogo volcanoes, intense circulation of volcanic fluids at depth leads to high CO<sub>2</sub> outgassing and flank destabilisation, whereas its neighbour Congro Fissural volcanic system, located between Fogo and Furnas volcanoes, experiences significant seismic swarm activity and poses considerable threat to the local population. Enhanced electrical conductivity values are typically associated with volcanic-hydrothermal systems and the modelled conductivity structures can provide constraints on these volcanic and hydrothermal processes.</p><p>Our previous work on Furnas volcano, which yielded a revised conceptual model developed from 39 high-frequency magnetotelluric soundings that imaged the hydrothermal system of the volcano to a depth of 1 km directly beneath the caldera, has now been expanded to include 35 additional broad-band magnetotelluric soundings from a recent field campaign conducted in late 2018, to image deeper and broader to gain new insights into the regional context of the Furnas volcanic system. The resistivity model of Furnas shallow hydrothermal system constructed from high-frequency dataset delineated two enhanced conductive zones, one at 100 m and another at 500 m depth, separated by a resistive layer. The shallow conductor has conductivity less than 1 S/m, which can be explained by clay mineral surface conduction with a mass fraction of at least 20% smectite. The deeper conductor extends across the majority of the survey area and is located at depths where smectite is generally not formed. We interpret this as the result of saline aqueous fluids near the boiling point, inferring temperatures of at least 240 <sup>o</sup>C. The less conductive layer found between these conductors is interpreted to be steam-dominated and coincides within the mixed-clay zone found in many volcanic hydrothermal systems. 3-D inversions using the deep-probing data indicate continuation of a strong conductive zone towards the south, beneath the 1630 Dome, which represents the most recent phase of eruptive activity in the multi-caldera complex. During the 2018 field campaign, we have enlarged our study to include 50 broad-band soundings on the adjacent Fogo (Água de Pau) volcano and Congro Fissural volcanic system. The Fogo-Congro region is subjected to seismic swarm activity and its relationship with the geoelectrical structure is being investigated.</p>

Seismo-volcanic source mechanism in White Island's hydrothermal system

2020 ◽  
Author(s):  
Dinko Sindija ◽  
Jurgen Neuberg
Keyword(s):  
Phase Change ◽  
Hydrothermal System ◽  
Pure Water ◽  
Hydrothermal Systems ◽  
Seismic Signals ◽  
Magma Body ◽  
Volcanic System ◽  
Volcanic Source ◽  
Phreatic Eruptions ◽  
Pressure Changes

<p>The signals preceding and accompanying phreatic eruptions, although observed on many volcanoes, are still not very well understood. As this type of eruption can have severe consequences, we need to understand the processes and the observed seismic signals leading up to these eruptions. Using seismic broadband instruments, we can detect signals in a wide frequency range, and careful analysis and modelling of these data can help us understand these processes. Phreatic eruptions are often accompanied, and sometimes preceded, by Very Long Period (VLP) seismic signals. These signals are caused by sudden pressure changes inside the volcanic system and in hydrothermal environments these pressure changes and, therefore, observed VLPs are attributed to the sudden expansion of water-filled cracks by vapourisation due to heat flow from the underlying magma body. <br>However previous studies consider pure water-water systems which sometimes assume unrealistic pressure-temperature changes in the system to produce a violent phase change from water to vapour. As there are instances of significant amounts of CO<sub>2</sub> measured within hydrothermal systems, we model how a sudden injection of CO<sub>2</sub> into the hydrothermal system, which would easily allow for explosive phase change could trigger the observed VLPs. Further, we show how poroelastic medium responds to such a source.</p>

scholarly journals Response of a hydrothermal system to escalating phreatic unrest: the case of Turrialba and Irazú in Costa Rica (2007–2012)

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
D. Rouwet ◽  
R. Mora-Amador ◽  
C. Ramírez ◽  
G. González ◽  
E. Baldoni ◽  
...  
Keyword(s):  
Costa Rica ◽  
Hydrothermal System ◽  
Crater Lake ◽  
Removal Rate ◽  
Summit Crater ◽  
Hydrothermal Systems ◽  
Thermal Springs ◽  
Total Output ◽  
Crater Lakes ◽  
Phreatic Eruptions

AbstractThis study presents the first hydrogeochemical model of the hydrothermal systems of Turrialba and Irazú volcanoes in central Costa Rica, manifested as thermal springs, summit crater lakes, and fumarolic degassing at both volcanoes. Our period of observations (2007–2012) coincides with the pre- and early syn-phreatic eruption stages of Turrialba volcano that resumed volcanic unrest since 2004, after almost 140 years of quiescence. Peculiarly, the generally stable Irazú crater lake dropped its level during this reawakening of Turrialba. The isotopic composition of all the discharged fluids reveals their Caribbean meteoric origin. Four groups of thermal springs drain the northern flanks of Turrialba and Irazú volcanoes into two main rivers. Río Sucio (i.e. “dirty river”) is a major rock remover on the North flank of Irazú, mainly fed by the San Cayetano spring group. Instead, one group of thermal springs discharges towards the south of Irazú. All thermal spring waters are of SO4-type (i.e. steam-heated waters), none of the springs has, however, a common hydrothermal end-member. A water mass budget for thermal springs results in an estimated total output flux of 187 ± 37 L/s, with 100 ± 20 L/s accounted for by the San Cayetano springs. Thermal energy release is estimated at 110 ± 22 MW (83.9 ± 16.8 MW by San Cayetano), whereas the total rock mass removal rate by chemical leaching is ~ 3000 m3/year (~ 2400 m3/year by San Cayetano-Río Sucio). Despite Irazú being the currently less active volcano, it is a highly efficient rock remover, which, on the long term can have effects on the stability of the volcanic edifice with potentially hazardous consequences (e.g. flank collapse, landslides, phreatic eruptions). Moreover, the vapor output flux from the Turrialba fumaroles after the onset of phreatic eruptions on 5 January 2010 showed an increase of at least ~ 260 L/s above pre-eruptive background fumarolic vapor fluxes. This extra vapor loss implies that the drying of the summit hydrothermal system of Turrialba could tap deeper than previously thought, and could explain the coincidental disappearance of Irazú’s crater lake in April 2010.

scholarly journals Analysis of Hydrothermal Systems Beneath Tayukeng through Long-Term Geochemical Signals of Hydrothermal Fluids in Tatun Volcano Group, Taiwan

2021 ◽  
Vol 18 (14) ◽  
pp. 7411
Author(s):  
Hsin-Fu Yeh ◽  
Hung-Hsiang Hsu
Keyword(s):  
Surface Temperature ◽  
Hydrothermal System ◽  
Hydrothermal Fluid ◽  
Thermal Water ◽  
Hydrothermal Systems ◽  
Hydrothermal Fluids ◽  
Geochemical Variations ◽  
Northern Taiwan

The Tatun Volcano Group (TVG) is located in northern Taiwan and consists of many springs and fumaroles. The Tayukeng (TYK) area is the most active fumarole site in the TVG. In this study, we analyzed the long-term geochemical variations of hydrothermal fluids and proposed a mechanism responsible for the variation in TYK. There are two different aquifers beneath the TYK area: a shallow SO42−-rich aquifer and a deeper aquifer rich in Cl−. TYK thermal water was mainly supplied by the shallow SO42−-rich aquifer; therefore, the thermal water showed high SO42− concentrations. After 2015, the inflow of deep thermal water increased, causing the Cl− concentrations of the TYK to increase. Notably, the inferred reservoir temperatures based on quartz geothermometry increased; however, the surface temperature of the spring decreased. We inferred that the enthalpy was lost during transportation to the surface. Therefore, the surface temperature of the spring does not increase with an increased inflow of deep hydrothermal fluid. The results can serve as a reference for understanding the complex evolution of the magma-hydrothermal system in the TVG.

Mercury concentrations in thermal waters of the Bolshoi Semyachik hydrothermal system, Russia, Kamchatka.

2021 ◽  
Author(s):  
Anton Nuzhdaev
Keyword(s):  
Hydrothermal System ◽  
Kamchatka Peninsula ◽  
Hydrothermal Systems ◽  
Thermal Waters ◽  
Hydrothermal Solutions ◽  
Average Value ◽  
Thermal Fields ◽  
Gas Jets ◽  
First Time ◽  
Hydrothermal Fields

<p>The study of mercury receipt within volcanic activity zones and large hydrothermal systems recently causes the big interest connected with attempts of an estimation of volumes of natural mercury receipt on a daily surface.</p><p>The hydrothermal system connected with volcanic massif Big Semyachik is one of the largest on the territory of Kamchatka peninsula. On the surface, the hydrothermal system is manifested by three large hydrothermal fields - the Verhnee Field, the parychay Dolina, and the Northern Crater of the Central Semyachik, the heat export from which is estimated at 300 MW (Vakin, 1976). On the surface of the thermal fields hot thermal waters and powerful steam-gas jets are unloaded.  At the same time, due to the inaccessibility of thermal fields remain poorly studied, and in particular, there is no information on the concentrations of mercury in hydrothermal solutions.</p><p>During fieldwork in 2020 all types of thermal waters were sampled, chemical types of waters were established, concentrations of mercury in hydrothermal solutions: for hot thermal waters the average value of mercury was - 0.44 mcg / L, and in steam-gas jets - the average value of mercury was - 4.60 mcg / L.</p><p>Thus, in the course of the work the data on concentrations of mercury in hydrothermal solutions of one of the largest hydrothermal systems of Kamchatka were received for the first time.</p><p> </p>

scholarly journals Hydrothermal systems generation scheduling using cultural algorithm

2009 ◽  
Vol 11 (1) ◽  
pp. 65-78 ◽  
Author(s):  
Xiaohui Yuan ◽  
Hao Nie ◽  
Yanbin Yuan ◽  
Anjun Su ◽  
Liang Wang
Keyword(s):  
Differential Evolution ◽  
Heuristic Search ◽  
Hydrothermal System ◽  
Selection Criteria ◽  
Optimization Methods ◽  
Hydrothermal Systems ◽  
Cultural Algorithm ◽  
Short Term ◽  
Generation Scheduling ◽  
Simple Selection

This paper proposes an enhanced cultural algorithm to solve the short-term generation scheduling of hydrothermal systems problem, in which differential evolution is embedded into a cultural algorithm and applies two knowledge sources to influence the variation operator of differential evolution and couples with simple selection criteria based on feasibility rules and heuristic search strategies to handle constraints in the cultural algorithm effectively. A test hydrothermal system is used to verify the feasibility and effectiveness of the proposed method. Results are compared with those of other optimization methods reported in the literature. It is shown that the proposed method is capable of yielding higher quality solutions.

Geochemical characterization and origins of the thermal springs in southern Gaoligong Mountains, China

2014 ◽  
Vol 72 (8) ◽  
pp. 3089-3098 ◽  
Author(s):  
Li Xiangquan ◽  
Hou Xinwei ◽  
Zhou Zhichao ◽  
Liu Lingxia
Keyword(s):  
Thermal Springs ◽  
Geochemical Characterization

scholarly journals Review article: Brief history of volcanic risk in Neapolitan area (Campania, Southern Italy): a critical review

2021 ◽  
Author(s):  
Stefano Carlino
Keyword(s):  
Southern Italy ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Campi Flegrei ◽  
Volcanic Risk ◽  
Campania Region ◽  
Systematic Strategy ◽  
History Of ◽  
Very High ◽  
Island Of Ischia

Abstract. The presence of three active volcanoes (Vesuvius, Campi Flegrei and Ischia Island) along the coast of Naples did not constrained the huge expansion of the urbanized zones around them. On the contrary, since Greek-Roman era, volcanoes have been an attractor for people who colonized Campania region. Stable settlements around Vesuvius, Campi Flegrei caldera and the Island of Ischia were progressively enlarged, reaching the maximum growth-rate between 1950 and 1980. Between 1982 and 1984, Neapolitan people faced the last and most dramatic volcanic crises, occurred at Campi Flegrei (Pozzuoli), without an eruption. Since that time, volcanologists have focused the attention on the problem of risk associated to eruptions in Neapolitan area, but a systematic strategy to reduce the very high volcanic risk of this area still lacks. A brief history of volcanic risk in Neapolitan district is here reported, trying to obtain new food for thought for the scientific community which works to the mitigation of volcanic risk of this area.

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