Monitoring the response of volcanic CO2 emissions to changes in the Los Humeros hydrothermal system

AbstractCarbon dioxide is the most abundant, non-condensable gas in volcanic systems, released into the atmosphere through either diffuse or advective fluid flow. The emission of substantial amounts of CO2 at Earth’s surface is not only controlled by volcanic plumes during periods of eruptive activity or fumaroles, but also by soil degassing along permeable structures in the subsurface. Monitoring of these processes is of utmost importance for volcanic hazard analyses, and is also relevant for managing geothermal resources. Fluid-bearing faults are key elements of economic value for geothermal power generation. Here, we describe for the first time how sensitively and quickly natural gas emissions react to changes within a deep hydrothermal system due to geothermal fluid reinjection. For this purpose, we deployed an automated, multi-chamber CO2 flux monitoring system within the damage zone of a deep-rooted major normal fault in the Los Humeros Volcanic Complex (LHVC) in Mexico and recorded data over a period of five months. After removing the atmospheric effects on variations in CO2 flux, we calculated correlation coefficients between residual CO2 emissions and reinjection rates, identifying an inverse correlation of ρ = − 0.51 to − 0.66. Our results indicate that gas emissions respond to changes in reinjection rates within 24 h, proving an active hydraulic communication between the hydrothermal system and Earth’s surface. This finding is a promising indication not only for geothermal reservoir monitoring but also for advanced long-term volcanic risk analysis. Response times allow for estimation of fluid migration velocities, which is a key constraint for conceptual and numerical modelling of fluid flow in fracture-dominated systems.

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Episodic fluid flow in an active fault

Geology ◽

10.1130/g46254.1 ◽

2019 ◽

Vol 47 (10) ◽

pp. 938-942 ◽

Cited By ~ 8

Author(s):

Sarah Louis ◽

Elco Luijendijk ◽

István Dunkl ◽

Mark Person

Keyword(s):

Fluid Flow ◽

Numerical Models ◽

Damage Zone ◽

Normal Fault ◽

Geothermal Gradient ◽

Hydrothermal Activity ◽

The Past ◽

Discharge Rates ◽

Fault Damage Zone ◽

Wide Zone

Abstract We present a reconstruction of episodic fluid flow over the past ∼250 k.y. along the Malpais normal fault, which hosts the Beowawe hydrothermal system (Nevada, USA), using a novel combination of the apatite (U-Th)/He (AHe) thermochronometer and a model of the thermal effects of fluid flow. Samples show partial resetting of the AHe thermochronometer in a 40-m-wide zone around the fault. Numerical models using current fluid temperatures and discharge rates indicate that fluid flow events lasting 2 k.y. or more lead to fully reset samples. Episodic fluid pulses lasting 1 k.y. result in partially reset samples, with 30–40 individual fluid pulses required to match the data. Episodic fluid flow is also supported by an overturned geothermal gradient in a borehole that crosses the fault, and by breaks in stable isotope trends in hydrothermal sinter deposits that coincide with two independently dated earthquakes in the past 20 k.y. This suggests a system where fluid flow is triggered by repeated seismic activity, and that seals itself over ∼1 k.y. due to the formation of clays and silicates in the fault damage zone. Hydrothermal activity is younger than the 6–10 Ma age of the fault, which means that deep (∼5 km) fluid flow was initiated only after a large part of the 230 m of fault offset had taken place.

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Eruptive history and petrochemistry of the Bulusan volcanic complex: Implications for the hydrothermal system and volcanic hazards of Mt. Bulusan, Philippines

Geothermics ◽

10.1016/0375-6505(93)90029-m ◽

1993 ◽

Vol 22 (5-6) ◽

pp. 417-434 ◽

Cited By ~ 20

Author(s):

Francisco G. Delfin ◽

Conrado C. Panem ◽

Marc J. Defant

Keyword(s):

Hydrothermal System ◽

Volcanic Hazards ◽

Volcanic Complex ◽

Eruptive History

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A synthesis of geological and geochemical investigations of the TAG hydrothermal field: Insights into fluid-flow and mixing processes in a hydrothermal system

Ophiolites and oceanic crust: new insights from field studies and the Ocean Drilling Program ◽

10.1130/0-8137-2349-3.213 ◽

2000 ◽

Cited By ~ 19

Author(s):

Susan E. Humphris ◽

Margaret K. Tivey

Keyword(s):

Fluid Flow ◽

Hydrothermal System ◽

Hydrothermal Field ◽

Mixing Processes ◽

Tag Hydrothermal Field

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Spatial distribution of micrometre‐scale porosity and permeability across the damage zone of a reverse‐reactivated normal fault in a tight sandstone: Insights from the Otway Basin, SE Australia

Basin Research ◽

10.1111/bre.12345 ◽

2019 ◽

Vol 31 (3) ◽

pp. 640-658 ◽

Cited By ~ 3

Author(s):

Natalie Debenham ◽

Natalie J. C. Farrell ◽

Simon P. Holford ◽

Rosalind C. King ◽

David Healy

Keyword(s):

Spatial Distribution ◽

Damage Zone ◽

Normal Fault ◽

Tight Sandstone ◽

Porosity And Permeability

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Thermophysical reservoir properties of the Hauptdolomit-facies underneath the Viennese basin across fault zones analogues – a reservoir study for the GeoTief EXPLORE project

10.5194/egusphere-egu2020-21332 ◽

2020 ◽

Author(s):

Doris Rupprecht ◽

Sven Fuchs ◽

Andrea Förster ◽

Mariella Penz-Wolfmayr

Keyword(s):

Thermal Conductivity ◽

Thermal Diffusivity ◽

Fractured Rocks ◽

Damage Zone ◽

Fault Zones ◽

Rock Properties ◽

Zone Model ◽

Geothermal Resources ◽

Fault Rocks ◽

The Impact

The GeoTief EXPLORE project aims to explore the geothermal potential and quantify the geothermal resources of the Vienna Basin (Austria) and the underlying Northern Calcareous Alpine basement. The main target of geothermal interest is the massive and tectonically remolded Hauptdolomite facies that has been identified as potential geothermal reservoir in previous studies. Now, this formation is studied using outcrop analogues for the investigation of their petrophysical characterization and specific thermal properties (thermal conductivity and thermal diffusivity).&#160;Here, we report new measurements on a total of 60 samples from 6 outcrops in and around the area of Vienna applying different methods for the laboratory measurement of thermal and hydraulic rock properties. The petrophysical analysis considers the impact of deformation along and across fault zones, which introduces heterogeneity of storage properties and consequently in the thermophysical properties. Using the standard fault core and damage zone model, outcrop samples were grouped into unfractured and fractured protoliths, as well as in fault rocks, like breccias and cataclasites. Rock samples are then classified by their fracture density (m&#178; fracture surface per m&#179; rock) and by their matrix content and differences in grain sizes, respectively.&#160;The measured thermal rock properties vary significantly between the selected rock groups. The total range [90 % of values] is between 3.2 and 5.0 W/(mK) for thermal conductivity and between 1.3 and 2.7 mm&#178;/s for thermal diffusivity. The results generally met the expected trend for fractured rocks as conductivity and diffusivity decreases with increasing porosity under unsaturated and saturated conditions. The total porosities are less than 5%. The variability of thermal conductivity under saturated conditions shows complex trends depending on the different rock classifications where fault rocks and highly fractured rocks of the damage zone show lower increase in thermal conductivities.&#160;The new petrophysical characterization will be the base for further numerical investigations of the hydraulic and thermal regime as well as for the analysis of the geothermal resources of the Hauptdolomite.&#160;&#160;&#160;&#160;

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Integration of geophysical methods and fractures study for the Vallès geothermal system characterization (NE Spain)

10.5194/egusphere-egu2020-6769 ◽

2020 ◽

Author(s):

Gemma Mitjanas ◽

Juanjo Ledo ◽

Pilar Queralt ◽

Gemma Alías ◽

Perla Piña ◽

...

Keyword(s):

Fluid Flow ◽

Geophysical Methods ◽

Normal Fault ◽

Hot Water ◽

Fault System ◽

Geothermal System ◽

Thin Sections ◽

Main Structure ◽

Geological Map ◽

Ne Spain

The Vall&#232;s geothermal system is located in the Catalan Coastal Ranges (CCR) (NE Spain). The CCR are formed by horst and graben structures limited by NE-SW and ENE-WSW striking normal faults, developed during the opening of the Valencia Trough (northwestern Mediterranean) (Gaspar-Escribano et al., 2004). In the Vall&#232;s Basin area, the thermal anomaly is located in the northeastern horst-graben limit, where a highly fractured Hercynian granodiorite is in contact with Miocene rocks by a major normal fault. This main structure seems to control the heat and the hot-water flow, nevertheless, the geological structure of this area, as well as the role of the Vall&#232;s normal fault, is poorly understood.Magnetotellurics and gravity methods together with a detailed geological map have been applied in this area to understand the main structure. Although the geophysical part makes up most of the study, we are also elaborating a detailed geological map of the area, making a fractures study at different scales. We are working with DEM alignments analysis, and fractures study from outcrops and thin sections.Our preliminary results in gravity show a strong gravity gradient in the NE-SW Vall&#232;s half-graben system and the recent MT profiles image the main fault of that system (Vall&#232;s normal fault). These results show a basin geometry with the major thickness of the basin towards the depocenter, disagreeing with the roll-over geometry assumed in previous works.Interpretations of the fractures study, together with geophysical data and models, have allowed a preliminary characterization of damage zones associated with the fault system, which are directly related to the fluid flow and the hot springs. The nature of this damage zones could be related to relay ramps, commonly regarded as efficient conduits for fluid flow (Fossen and Rotevatn, 2016).

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