Active volcanoes are associated with microearthquake (MEQ) hypocenters that form plane-oriented cluster distributions. These are faults delineating a magma injection system of dykes and sills. The ...Frac-Digger program was used to track fracking faults in the Kamchatka active volcanic belt and fore-arc region of Russia. In the case of magma laterally injected from volcanoes into adjacent structures, high-temperature hydrothermal systems arise, for example at Mutnovsky and Koryaksky volcanoes. Thermal features adjacent to these active volcanoes respond to magma injection events by degassing CO2 and by transient temperature changes. Geysers created by CO2-gaslift activity in silicic volcanism areas also flag magma and CO2 recharge and redistributions, for example at the Uzon-Geyserny, Kamchatka, Russia and Yellowstone, USA magma hydrothermal systems. Seismogenic faults in the Kamchatka fore-arc region are indicators of geofluid fracking; those faults can be traced down to 250 km depth, which is within the subduction slab below primary magma sources.
Secondary minerals assemblages that are deposited from thermal solutions at the top of geysers (Velikan, Bolshoy) were investigated. It is established that assemblages are represented mainly by opal ...and high-silica zeolites (mordenite and heulandite). As conditions of feeding hydrothermal reservoir change, minerals of the kaolinite group and smectites may appear.
This study reports and interprets observational data of geyser cycling in the Valley of Geysers and Uzon hydrothermal systems between 2007 and 2015. The monitoring of the Velikan and Bolshoy Geysers ...after the catastrophic landslide on 3.06.2007 (which dammed and created Podprudnoe Lake, drowning some geysers) and before a mudflow on 3.01.2014 (which destroyed the dam and almost completely drained Podprudnoe Lake) shows that the interval between eruptions (IBE) of the Bolshoy Geyser decreased from 108 to 63min and that the IBE of the Velikan Geyser slowly declined over three years from 379min to 335min. The seasonal hydrological cycle of the Velikan Geyser shows an increase in the IBE during winter (average of 41min). The dilution of the chloride deep components of the Bolshoy (−23%) and Velikan Geysers (−12%) is also observed. A local TOUGH2 model of the Velikan Geyser is developed. This model is used to describe the transient thermal hydrodynamic and CO2 changes in a Velikan Geyser conduit during the entire cycling process by using cyclic, time-dependent boundary mass flow conditions (major eruption discharge and sub-cyclically assigned CO2 mass flow recharge into the base of the geyser conduit and water recharge at the mid-height of the geyser conduit) and a constant mass flow of water into the geyser at depth. This model also indicates a seepage element at the conduit's top to allow pre-eruptive discharge and a buffering isothermal reservoir below to compensate for pressure declines from major eruptions at earlier times. A local TOUGH2 model is successfully calibrated against temperature observations at both the mid-height and base of the conduit of the Velikan Geyser, which shows the essential role of the above parameters in describing the functionality of the geyser. A reservoir model of shallow production geysers is also developed. This 2D model is used to describe changes in the thermal hydrodynamic state and evolving chloride concentrations in the areas of most prominent discharge, both at steady state and when perturbed by cold water injection from Podprudnoe Lake and other cold water sources (after 3.06.2007). A “well on deliverability” option is used to model the geyser discharge features in the model. The modeled increases in geyser discharge that is caused by an increase in the reservoir pressure from cold water injection reasonably matches observations of IBE decreases in the Bolshoy (~58%) and Velikan Geysers (~9%). The modeling also shows the possibility of chloride dilution in the Velikan Geyser but no dilution in the Bolshoy Geyser. The latter observation is attributed to the presence of direct cold water inflow into the Bolshoy Geyser conduit.
•Velikan and Bolshoy Geysers showed that Interval Between Eruptions (IBE) are sensitive to giant landslides and seasonal events.•A local TOUGH2 model demonstrated the essential role of CO2 cyclic flux in regulating the eruption periodicity.•The modeled geyser discharge increased due to cold water injection from Lake is matched the observed geyser IBE decreases.
This special issue comprises 12 papers from authors in 10 countries with new insights on the close coupling between magma as an energy and fluid source with hydrothermal systems as a primary control ...of magmatic behavior. Data and interpretation are provided on the rise of magma through a hydrothermal system, the relative timing of magmatic and hydrothermal events, the temporal evolution of supercritical aqueous fluids associated with ore formation, the magmatic and meteoric contributions of water to the systems, the big picture for the highly active Krafla Caldera, Iceland, as well as the implications of results from drilling at Krafla concerning the magma–hydrothermal boundary. Some of the more provocative concepts are that magma can intrude a hydrothermal system silently, that coplanar and coeval seismic events signal “magma fracking” beneath active volcanoes, that intrusive accumulations may far outlast volcanism, that arid climate favors formation of large magma chambers, and that even relatively dry rhyolite magma can convect rapidly and so lack a crystallizing mush roof. A shared theme is that hydrothermal and magmatic reservoirs need to be treated as a single system.
Here, we report on a new geyser (named Shaman) formed in the Uzon caldera (Kronotsky Federal Nature Biosphere Reserve, Russia) in autumn 2008 from a cycling hot Na-Cl spring. The geyser is a ...pool-type CO2-gas lift driven. From 2012 to 2018, the geyser has shown a rather stable interval between eruptions (IBE) from 129 to 144 min with a fountain height up to 4 m, and the geyser conduit has gradually enlarged. In 2019, the Shaman geyser eruption mode significantly changed: cold water inflow from the adjacent stream was re-directed into the geyser conduit and the average IBE decreased to 80 min. We observed two eruptive modes: a cycling hot spring (June 2019) and a cycling geyser (after June 2019). Bottom-hole temperature recording was performed in the geyser conduit to understand its activity. The TOUGH2-EOS2 model was used to reproduce the obtained temperature records and estimate geyser recharge/discharge parameters in both modes. Modeling shows that a larger cold inflow into the conduit causes a switch from cycling geyser to hot cycling spring mode. It was also found that the switch to cycling geyser mode corresponds to a larger mass of CO2 release during the time of the eruption.
The thermal, hydrogeological, and chemical processes affecting Kamchatka geothermal reservoirs were studied by using isotope and geochemistry data: (1) The Geysers Valley hydrothermal reservoirs; (2) ...The Paratunsky low temperature reservoirs; (3) The North-Koryaksky hydrothermal system; (4) The Mutnovsky high temperature geothermal reservoir; (5) The Pauzhetsky geothermal reservoir. In most cases water isotope in combination with Cl
-
transient data are found to be useful tool to estimate reservoirs natural and disturbed by exploitation recharge conditions, isotopes of carbon-13 (in CO
2
) data are pointed either active magmatic recharge took place, while SiO
2
and Na-K geothermometers shows opposite time transient trends (Paratunsky, Geysers Valley) suggest that it is necessary to use more complicated geochemical systems of water/mineral equilibria.
The temperature in the Valley of Geysers (Kamchatka) geothermal reservoir calculated using the feldspar Na-K-geothermometer has been steadily increasing over the past 10 years on average from 165 to ...235 °C, which is close to the temperature values of a hydrothermal explosion of the steam and water mixture. For the analysis of chemical geothermometers, TOUGHREACT-simulation was used, with the help of which the previously known Na-K feldspar geothermometer was reproduced on a single-element model and new formulas were obtained for three Na-K geothermometers: zeolite, smectite, and based on volcanic glass. Data of chemical analysis for the period 1968-2018, in which the chloride ion is considered as an inert tracer of geofiltration processes, indicates that after 2007 a significant inflow of infiltration water (its mass fraction is estimated from 5 to 15 %) into the Geyser reservoir. It is assumed that the Na-K increased values of the feldspar geothermometer are not the result of the temperature increase in the Geyser reservoir, but the effect of smectite water dilution.
A three-dimensional numerical model of the Pauzhetsky geothermal field has been developed based on a conceptual hydrogeological model of the system. It extends over a 13.6-km super(2) area and ...includes three layers: (1) a base layer with inflow; (2) a geothermal reservoir; and (3) an upper layer with discharge and recharge/infiltration areas. Using the computer program iTOUGH2 Finsterle, S., 2004. Multiphase inverse modeling: review and iTOUGH2 applications. Vadose Zone J. 3, 747-762, the model is calibrated to a total of 13,675 calibration points, combining natural-state and 1960-2006 exploitation data. The principal model parameters identified and estimated by inverse modeling include the fracture permeability and fracture porosity of the geothermal reservoir, the initial natural upflow rate, the base-layer porosity, and the permeabilities of the infiltration zones. Heat and mass balances derived from the calibrated model helped identify the sources of the geothermal reserves in the field. With the addition of five make-up wells, simulation forecasts for the 2007-2032 period predict a sustainable average steam production of 29 kg/s, which is sufficient to maintain the generation of 6.8 MWe at the Pauzhetsky power plant.
The paper describes the role of hydrothermal fluid circulation in the creation of porous reservoirs bounded by low–permeability layers in volcanogenic rocks, which can accumulate fluids of different ...origin and phase conditions. The Rogozhnikovsky oil-bearing volcanogenic production reservoir in west Siberia, hosted in Triassic rhyolite tuffs and lavas, and the Mutnovsky high temperature geothermal reservoir hosted in recent rhyolites and andesites, are considered as benchmark examples. TOUGHREACT modeling scenarios show that formation of production reservoirs due to hydrothermal circulation may result from chemical fluid-rock interactions. The model shows short- term pressure drop conditions in the early stage of circulation (favorable for fluid migration into the reservoir), followed by reservoir self-sealing at the last stage of hydrothermal circulation (favorable for fluid trapping and formation of mineral resource deposits).
A large dike intrusion and fissure eruption lasting 9months began on November 27, 2013, beneath the south flank of Tolbachik Volcano, Kamchatka, Russia. The eruption was the most recent at Tolbachik ...since the Great Tolbachik Eruption from 1975 to 1976. The 2012 eruption was preceded by more than 6months of seismicity that clustered beneath the east flank of the volcano along a NW–SE trend. Seismicity increased dramatically before the eruption, with propagation of the seismicity from the central volcano conduit in the final hours. We use interferometric synthetic aperture radar (InSAR) to compute relative displacement images (interferograms) for SAR data pairs spanning the eruption. We use satellite SAR data from the Canadian Space Agency's RADARSAT-2 and from the Italian Space Agency's COSMO-SkyMed missions. Data are modeled first through a Markov Chain Monte Carlo solution for a single tensile dislocation (dike). We then use a boundary element method that includes topography to model a distributed dike-opening model. We find the best-fitting dike dips 80° to the WNW with maximum opening of 6–8m, localized in the near surface and more broadly distributed in distinct regions up to 3km beneath the surface, which varies from 1 to 2km elevation for the eruptive fissures. The distribution of dike opening and its correspondence with co-diking seismicity suggests that the dike propagated radially from Tolbachik's central conduit.
•Satellite InSAR data constrains a shallow distributed dike model.•Seismic swarm occurred prior to the eruption SE of Tolbachik.•The dike model and timing of seismicity suggests lateral dike propagation.
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