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Red Geysers are galaxies with low-star formation rates and galactic scale ionized outflows likely driven by low-luminosity active galactic nuclei (AGN). We investigated the impact of AGN winds on the oxygen abundance using integral field spectroscopic data from Mapping Nearby Galaxies for Red Geysers, control galaxies (quiescent galaxies without outflows), and AGN hosts within the inner 1.5 kpc radius. Red Geyser galaxies have higher W |$_{80}$| values compared to those of AGN and controls, with 64 per cent showing W |$_{80}\gt 500$|  km s |$^{-1}$| that is indicative of outflow. Only 40 per cent of controls and 31 per cent of AGNs reach this value. We found a small tendency of the oxygen abundance distribution of controls to be biased towards higher values than those of Red Geysers. However, Red Geysers do not show a correlation between H |$\alpha$| width (parametrized by the W |$_{\rm 80}$|⁠) and oxygen abundance, which indicates that AGN winds are not significantly impacting the chemical abundance of the nuclear region of these galaxies. The oxygen abundance distribution mean value for the tree samples is |$\rm 12+log(O/H)\sim$| 8.7 (⁠|$\mathit{Z}\sim \rm Z_{\odot })$|⁠. On the other hand, AGN hosts show a positive correlation between W |$_{80}$| and O/H which could be due to star formation that outflows from the active nuclei could induce; or to the reservoir of gas that makes the nucleus active, and its is also used in the star formation. [ABSTRACT FROM AUTHOR]

In 2020, in the caldera of Uzon volcano (Kamchatka Peninsula), electrical prospecting studies were carried out using the electrotomography method within the eastern thermal field near Shaman geyser. The geoelectric section is divided into three zones according to the level of electrical resistivity: relatively high-resistivity cold zones at the edges and a relatively low-resistivity hot zone in the center. The hot zone, situated at a depth of 5–20 m and hosting the Shaman geyser, is distinguished by anomalously low resistivity (less than 0.5 Ω m), which indicates the highest fracturing and saturation of rocks with fluid. Resistivity monitoring was carried out above the geyser using an Omega-48 electrical tomography station and two cables with lengths of 235 and 47 m. The first cable provided a survey depth of 60 m; the second, ∼12 m. Four phases of the geyser's operation are distinguished on the difference geoelectric sections, constructed from the monitoring results: filling, outpouring, spouting, and steaming in the form of alternating positive and negative electric field anomalies. The channel to the geyser was found from the results of areal measurements. [ABSTRACT FROM AUTHOR]

There is considerable interest in sending a mission to Enceladus to sample its erupting materials, which are sourced from its ocean, a proposed habitable environment. However, we lack resolution between competing ascent and eruption models, which offer differing consequences and challenges for mission sampling and access strategies. We report a new Enceladus ascent and eruption model, "Cryo‐Erupt," where ascent from ocean to jet is driven by the exsolution and expansion of dissolved gases from ascending water within conduits. This mechanism shares many similarities with some forms of terrestrial activity, including explosive silicate volcanism, cold‐water geysers and "limnic" eruptions. This preliminary study suggests that this mode of ascent and eruption is viable and broadly consistent with a range of observations including the apparent co‐existence of point‐ (jet) and fissure‐ (curtain) sourced activity as well as strong contrasts in velocity and ice‐to‐vapor ratio between the plume and the jets feeding it. However, it requires the co‐existence of a sublimation plume as an additive component to the broader plume. The outcomes of the Cryo‐Erupt model differ in terms of conduit physical and chemical processes from previously proposed boiling interface eruption models, for example, predicting larger dynamic pressures and narrower conduits, which could present challenges for direct robotic access. Due to the lack of a static boiling interface or wall condensation, bulk composition is unlikely to change appreciably during ascent from the ocean‐conduit interface to the jet, potentially simplifying the interpretation of samples collected in space or on Enceladus' surface. Plain Language Summary: High‐speed jets from giant ice fissures on Saturn's moon Enceladus feed a large plume, which is of interest to scientists because it contains salts and organic compounds, which are evidence of a subsurface ocean that may possibly host life. However, it is unclear how the chemistry of the plume material (gas and grains) might be altered as this material moves from the ocean into space, and to what extent samples from the plume are representative of ocean composition. Previous models to predict this behavior mostly relied on boiling of water as the primary way that gas and droplets are ejected, but these models do not take into account all of the physics involved, and do not fully reproduce what Cassini observed at Enceladus. We propose a new model that instead invokes dissolved gas molecules expanding, similar to explosive volcanoes on Earth and essentially the same mechanism that causes cans of soda to explode upon opening if shaken. We predict that the erupting jets would largely preserve bulk ocean content and thus would be the best place to study ocean content, in contrast with the broader plume, which would have more water that has sublimated from the surface. Key Points: Recent studies on the ascent and eruption of Enceladus' plume have neglected the role of exsolution and expansion of dissolved volatilesVolatile‐driven direct ocean‐to‐jet liquid water ascent is generally consistent with observations if combined with a sublimation co‐plumeThis mode of ascent could preserve ocean bulk content in jets, leading to jet sampling strategies being preferred for future missions [ABSTRACT FROM AUTHOR]

The storm sewer geyser is a process where an air–water mixture violently erupts from a manhole. Despite the low hydrostatic pressure, violent eruptions can achieve a height of tens of meters above the ground. This current study experimentally investigates large-scale violent geysers using a large air pocket inserted from a pressurized air tank. The total length of the pipe system is approximately 88 m with a 0.1572 m diameter pipe. This large-scale experiment facilitates the investigation of spontaneous geyser eruptions. This study identifies the role of air–water volume ratio and coefficient of pressure (ratio of absolute initial static pressure to initial dynamic pressure) on the geyser intensity using eruption images and pressure plots. A total of 116 cases are tested, in which the volume ratio is parametrically increased from 0 to 1.1 under various operating conditions. A geyser score is defined to quantify the geyser eruption nature based on visual observations. The key findings are as follows: first, a sharp transition in geyser intensity is observed at the critical volume ratio of 0.5, and pre-transition and post-transition intensity exhibit a linear relationship with the volume ratio; and second, the critical volume ratio linearly varies with the coefficient of pressure. [ABSTRACT FROM AUTHOR]

Magmatism in the Quaternary Clear Lake volcanic field (CLVF), with its youngest eruption having only occurred c. 10 ka ago, is commonly invoked as the heat source for the world's largest commercial geothermal reservoir, The Geysers, in northern California. A shallow silicic magma reservoir in the upper-middle crust has been discovered for some time, but the location and mechanism of a potential deep mafic magma reservoir have remained elusive. Here, we present a seismic tomographic model that images the entire crustal column, clearly revealing a multilevel transcrustal magmatic system beneath the Geysers-Clear Lake area. Upwelling melts from the mantle traverse across the crust-mantle boundary and accumulate in the lower crust underneath the southeastern part of Clear Lake, resulting in a hot Moho in between. Mafic melts primarily ascend westward due to the extensional regime in the west and physical barrier effect from the overlying rigid ophiolite fragment, ultimately forming a shallow silicic magma reservoir underlying and heating The Geysers geothermal field. In addition, this study also links compositionally diverse volcanism in a continental setting to differentiation in a multilevel transcrustal magmatic system. [ABSTRACT FROM AUTHOR]

We analyze nearest‐neighbor proximities of earthquakes in California based on the joint distribution (T, R) of rescaled time T and rescaled distance R between pairs of earthquakes (Zaliapin & Ben‐Zion, 2013a, https://doi.org/10.1002/jgrb.50179), using seismic catalogs from several regions and several catalogs for the San Jacinto Fault Zone (SJFZ). The study aims to identify informative modes in nearest‐neighbor diagrams beyond the general background and clustered modes, and to assess seismic catalogs derived by different methods. The results show that earthquake clusters with large and small‐to‐medium mainshocks have approximately diagonal and horizontal (T, R) distributions of the clustered mode, respectively, reflecting different triggering distances of mainshocks. Earthquakes in the creeping section of San Andreas Fault have a distinct "repeaters mode" characterized by very large rescaled times T and very small rescaled distances R, due to nearly identical locations of repeating events. Induced seismicity in the Geysers and Coso geothermal fields follow mostly the background mode, but with larger rescaled times T and smaller rescaled distances R compared to tectonic background seismicity. We also document differences in (T, R) distributions of catalogs constructed by different techniques (analyst‐picks, template‐matching and deep‐learning) for the SJFZ, and detect a mode with very large R and small T in the template‐matching and deep‐learning based catalogs. This mode may reflect dynamic triggering by passing waves and/or catalog artifacts. Plain Language Summary: Earthquake patterns in space and time provide important information about the properties of active faults, the surrounding crust, and different loading mechanisms. Nearest‐neighbor diagrams of earthquake proximities in a combined space‐time‐magnitude domain can be used to detect different types of seismicity patterns. Using such diagrams to analyze several earthquake catalogs in California, we examine characteristics of different sections of the San Andreas and San Jacinto faults along with geothermal areas and the entire southern California. The results highlight features of seismicity beyond the well‐known background and clustered modes of earthquakes, including a mode of repeating events in the creeping section of the San Andreas fault and differences between events in regular tectonic areas and geothermal fields. Analyses of different catalogs for the region around the San Jacinto fault also reveal differences related to the different techniques used to construct the catalogs. The results show that nearest‐neighbor diagrams can provide a simple and efficient way to identify different types of seismicity and assess the quality of earthquake catalogs. Key Points: Nearest‐neighbor diagrams provide an efficient way to identify different types of earthquake patternsRepeating events, large versus small‐moderate mainshocks, and induced seismicity have characteristic signaturesNearest‐neighbor diagrams help to evaluate features in catalogs constructed by different methods [ABSTRACT FROM AUTHOR]

In recent years, due to high electricity prices in South Asian countries, natural gas-based tankless water heaters (instant geysers) have been widely installed for sustainable household water heating. The wastewater after household use is drained into the sewerage system, so a significant amount of heat energy is wasted with this water (usually at Th1 = 30–40 °C). In this work, the energy wasted with this wastewater is recovered to preheat the input water (from water tank at Tc1 = 5–10 °C) by using a heat exchanger between this high-temperature water and input water to the geyser. Due to variable input water temperature (Tin), the output temperature (Tout) can fluctuate; so, to obtain a constant output water temperature, a low-cost customized gas flowmeter was designed using servo motors. The difference in heat consumption rates (savings in the amount of gas consumption) in the geyser with and without using a heat exchanger (Q2) was compared with the speed of energy recovered in the heat exchanger (Q1). This research will provide some insights and considerations at the household level for sustainable operations of gas-based instant geysers. [ABSTRACT FROM AUTHOR]

The violent nature of storm sewer geysers has been puzzling researchers worldwide for a very long time. This paper investigates the geyser simulation methodology using a small-scale set-up, where important flow structures such as slugs, eruption patterns, and pressure oscillations are compared with experimental results to test the fidelity of the numerical modelling. In this exercise, a geyser-like process is produced using a continuous insertion of air in the horizontal pipe. The established methodology is used to simulate the hypothesized scenario of a finite trapped air pocket in the relatively longer pipe system. A geyser produced from a finitely trapped air pocket shows a different eruption mechanism compared to those found in previous studies. First, no slug is observed in the horizontal pipe, resulting in continuous air release. Second, the interface continuously atomizes in the vertical pipe, creating a churn-slug flow that produces a large number of small eruptions. [ABSTRACT FROM AUTHOR]

In this work, we study the trajectories of the dust particles ejected in the geysers of the moon Enceladus, inside its Hill sphere, where its gravitational influence dominates. Our goal is to determine the properties of the particles that escape from the moon or of those that eventually impact on its surface. The analysis considers the gravity of Enceladus, the Lorentz force due to Saturn's magnetic field and the gas drag from the geysers. The local magnetic field around Enceladus is derived from an interpolation of Cassini data from six flybys. In general, we obtain that grain sizes and launching speeds define whether grains escape, though the launching angle may also play an important role in some cases. Plain Language Summary: Dust grains expelled from the geysers of the small Saturnian moon Enceladus follow particular trajectories determined by the different forces like the gravity of the moon, the gas drag of the geysers and the magnetic field of Saturn. In this work we study the dynamics of these grains inside a region around the moon, called the Hill sphere, where its gravitational influence dominates, in order to determine the effects of the different forces on the grains, as well as the properties of grains, like their size, mass and electric charge. Key Points: We study the trajectories of dust grains from the geysers of Enceladus inside the Hill sphere of the moonWe implement an interpolated magnetic field background to study the trajectories of dust grainsWe study the dynamic properties of dust grains that are able to escape from Enceladus [ABSTRACT FROM AUTHOR]

Dirichlet process mixture models (or mixture of Dirichlet process [MDP]) are Bayesian non‐parametric mixture models that can solve the problem of determining the number of components in mixture models by assuming infinitely many components. We propose a new approach for MDP by using a matrix‐generalized half‐ t distribution as a non‐informative prior for the covariance in the base distribution. This new approach aims to improve the performance of MDP in cases where conjugacy constraints cause underperformance of current priors, such as Wishart distribution or inverse‐Wishart. The effectiveness of this approach is demonstrated through simulations and by comparing its performance on the Old Faithful geyser dataset with existing MDP specifications. [ABSTRACT FROM AUTHOR]

Transient (highly unsteady) air--water two-phase flows and spring-like geysers have been one of the critical concerns in drainage pipeline systems, which may cause or exacerbate drainage flooding problems and associated damage consequences. In this paper, the flow dynamics and energy evolution mechanism of the induced spring-like geysers are innovatively investigated through a two-phase full-2D numerical model developed in this study. After full validation by laboratory experimental tests conducted in this study, the proposed 2D model is systematically applied to simulate transient air--water flows in drainage pipelines. The results have shown acceptable accuracy of this full-2D model to capture the complex flow interactions between the air and water phases, and indicated that the velocity and pressure distribution patterns are highly relevant to the air--water interface deformation and energy exchange. The in-depth energy analysis demonstrates that the intermittent eruption of geysers could be attributed to the conservation and release of different energy forms during the transient air--water two-phase flow process. Besides, the numerical applications for the systems with different boundaries and initial conditions indicate that the different ventilation conditions and initially entrapped air volume may significantly affect the velocity distribution of the air phase, thereby playing an essential role to provide effective measures to mitigate unexpected geyser events and pressure oscillations in the system. The results and findings of this paper could provide insights to improve the theory and practice of transient air--water two-phase flows in drainage pipeline systems. [ABSTRACT FROM AUTHOR]

Geysers fascinate scientists and visitors for several centuries. However, many driving mechanisms such as heat transfer in the conduit and in the subsurface remain poorly understood. We document for the first time transient temperature variations inside the active Strokkur's and nearby quasi‐dormant Great Geysir's conduits, Iceland. While recording temperature inside the conduit, we visually monitored Strokkur's activity at the vent with a high‐speed camera, providing a high temporal resolution of the eruptions. Our results reveal heat transfer from a bubble trap to and through the conduit. We propose a model for the eruptive cycle of Strokkur that includes vapor slug rise, eruption, and conduit refill. Each water jet of an eruption is marked by an initial pulse of liquid water and vapor, emitted at a velocity between 5 and 28 m/s and generally followed by a second pulse less than a second later. The timing of eruptions coincides with temperature maxima in the conduit. After the eruption, the conduit is refilled by water falling back in the pool and drained from neighboring groundwater‐saturated geological units. This results in a temperature drop, the amplitude of which increases with depth while its period is reduced. This reflects faster heat transfer in the deeper than shallower part of the conduit. The amplitude of temperature drop following an eruption also increases with the eruption order, implying larger heat release by higher‐order eruptions. Temperature in the conduit subsequently increases until the next eruption, starting then a new cycle. Plain Language Summary: Geysers are hot springs that erupt intermittently. Although they have been studied for several centuries, many aspects such as heat transfer in the conduit and subsurface remains poorly understood. We recorded the temperature evolution inside the active Strokkur and quasi‐dormant Great Geysir geysers, located 100 m apart, in the Haukadalur hydrothermal field (Iceland). Comparing the timing of eruptions, visually monitored at Strokkur with its temperature records allowed us to characterize the thermal cycle associated with eruptions. Each eruption is marked by a temperature drop and subsequent rise inside the conduit to which we refer as the cooling and warming phases, respectively. We characterize the duration of these phases and the associated temperature variations, which revealed a faster heat transfer in the deeper than shallower part of the conduit and larger heat release by higher‐order eruption. A high‐speed camera revealed the eruption of a water jet in details. Each jet is marked by a first pulse of liquid water and vapor, emitted at a velocity between 5 and 28 m/s, which is generally followed by a second pulse, less than a second later. We propose a new and complementary model for vapor rise, eruption and, conduit refill of Strokkur. Key Points: In situ temperature evolution from an active geyser reveals heat transfer from a bubble trap to the conduitTransient measurement reveals the conduit dynamics during the geyser's eruptive cycleDetails of water jet eruptions captured by high‐speed camera [ABSTRACT FROM AUTHOR]

Simple Summary: Earthquakes are a common occurrence at The Geysers geothermal field in California which, over the years, have led to general land sinking in the area. In our study, we explore the correlation of geothermal data and seismicity and find that the injection rate exhibits a high correlation with the number of earthquakes. Additionally, we rely on satellite imagery which measures the extent of the land subsidence and develop a machine learning model that predicts future land subsidence, finding that it has a relatively low error rate. Moreover, we incorporate geothermal data into this model and find that it performs even better. All in all, this encourages the use of machine learning models in hazard mitigation in order to minimize the potential impacts that land subsidence might bring. The Geysers geothermal field in California is experiencing land subsidence due to the seismic and geothermal activities taking place. This poses a risk not only to the underlying infrastructure but also to the groundwater level which would reduce the water availability for the local community. Because of this, it is crucial to monitor and assess the surface deformation occurring and adjust geothermal operations accordingly. In this study, we examine the correlation between the geothermal injection and production rates as well as the seismic activity in the area, and we show the high correlation between the injection rate and the number of earthquakes. This motivates the use of this data in a machine learning model that would predict future deformation maps. First, we build a model that uses interferometric synthetic aperture radar (InSAR) images that have been processed and turned into a deformation time series using LiCSBAS, an open-source InSAR time series package, and evaluate the performance against a linear baseline model. The model includes both convolutional neural network (CNN) layers as well as long short-term memory (LSTM) layers and is able to improve upon the baseline model based on a mean squared error metric. Then, after getting preprocessed, we incorporate the geothermal data by adding them as additional inputs to the model. This new model was able to outperform both the baseline and the previous version of the model that uses only InSAR data, motivating the use of machine learning models as well as geothermal data in assessing and predicting future deformation at The Geysers as part of hazard mitigation models which would then be used as fundamental tools for informed decision making when it comes to adjusting geothermal operations. [ABSTRACT FROM AUTHOR]

The generation of strong earthquakes is a long‐debated problem in seismology, and its importance is increased by the possible implications for earthquake forecasting. It is hypothesized that the earthquake generation processes are anticipated by several phenomena occurring within a nucleation region. These phenomena, also defined as preparatory processes, load stress on the fault leading it to reach a critical state. In this paper, we investigate the seismicity preceding 19 moderate (Mw ≥ 3.5) earthquakes at The Geysers, Northern California, aiming to verify the existence of a preparatory phase before their occurrence. We apply an unsupervised K‐means clustering technique to analyze time series of physics‐related features extracted from catalog information and estimated for events occurred before the mainshocks. Specifically, we study the temporal evolution of the b‐value from the Gutenberg‐Richter (b), the magnitude of completeness (Mc), the fractal dimension (Dc), the inter‐event time (dt), and the moment rate (M˙0 ${\dot{M}}_{0}$). Our analysis shows that out of 19 moderate magnitude events considered, a common preparatory phase for 11 events is clearly identified, plus other five events for which we can guess a preparatory phase but with different characteristics from the previous ones. The latter result confirms that even within the same tectonic context different possible activation behaviors may exist. The duration of the preparatory process ranges between about 16 hr and 4 days. We observe that also for the retrieved preparatory process a decrease in b, Mc, and Dc, and an increase of M˙0 ${\dot{M}}_{0}$. Finally, we show a clear correlation between events with a preparation phase and the location of injection's wells, suggesting an important role of fluids in the preparatory process. Plain Language Summary: We investigate the preparatory phase of moderate magnitude‐induced earthquakes at The Geysers geothermal field in California by studying the spatiotemporal evolution and dynamic properties of small magnitude events and using an unsupervised machine learning approach. To this aim, we rely on features extracted from seismic catalog information that are used for a K‐means clustering analysis. Our results highlight changes in the seismicity characteristics before the moderate‐induced earthquakes. We find that most of the analyzed target earthquakes present a preparatory phase, and that most of the cases the latter presents common characteristics in their key features. We show that the seismicity clusters in space and time before moderate events also becoming more energetic. We estimate a duration for the detected preparatory phases that ranges from 16 hr to 4 days. Finally, we show that the presence of a preparatory phase is correlated to the proximity of injection's wells, suggesting a significant role of fluids in the earthquake's nucleation process. Key Points: Moderate‐induced earthquakes at The Geysers can be preceded by a preparatory phase detectable using K‐means clustering on catalog featuresThe detected preparatory phase has common characteristics presenting negative trends of b‐value, Mc, and Dc and a positive trend of M˙0 ${\dot{M}}_{0}$The earthquakes with a preparatory phase are located nearer to the injection's wells in the area than the events without it [ABSTRACT FROM AUTHOR]

We introduce a seismic identification method for collapse events using moment tensors (MTs). We start by computing full (six-element) MT solutions for 43 identified collapse events from around the world, and statistically characterizing the population on the MT hypersphere. We then test a large data set of over 1000 full MTs for the western U.S. against the distribution of collapses using a MT-based identification method similarly as used for testing explosions. Known collapses and explosions are readily identified, along with other anomalous events in the Geysers and central California coast. Misidentification rates are determined for various screening angles with optimal misidentification rates between earthquakes and collapses on the order of 3 per cent. The method is demonstrated to be very effective at identifying non-earthquake sources with a 97–98 per cent accuracy. It is likely to be transportable to other regions, and can be used for event identification anywhere full MT solutions are routinely calculated. [ABSTRACT FROM AUTHOR]

The present study describes the isolation of an extremely thermophilic bacterium from El Tatio, a geyser field in the high planes of Northern Chile. The thermophile bacterium named Thermus thermophilus strain ET-1 showed 99% identity with T. thermophilus SGO.5JP 17-16 (GenBank accession No. CP002777) by 16S rDNA gene analysis. Morphologically, the cells were non-sporeforming Gram-negative rods that formed colonies with yellow pigmentation. This strain is able to proliferate between 55 and 80 °C with a pH range of 6–10, presenting an optimum growth rate at 80 °C and pH 8. The bacterium produces an extracellular protease activity. Characterization of this activity in a concentrated enzyme preparation revealed that extracellular protease had an optimal enzymatic activity at 80 °C at pH 10, a high thermostability with a half-life at 80 °C of 10 h, indicating that this enzyme can be classified as an alkaline protease. The proteolytic enzyme exhibits great stability towards chelators, divalent ions, organic solvents, and detergents. The enzyme was inhibited by phenylmethylsulfonyl fluoride (PMSF), implying that it was a serine protease. The high thermal and pH stability and the resistance to chelators/detergents suggest that the protease activity from this T. thermophilus. strain could be of interest in biotechnological applications. [ABSTRACT FROM AUTHOR]

The well-known inspection paradox of renewal theory states that, in expectation, the inspection interval is larger than a common renewal interval, in general. For a random inspection time, which includes the deterministic case, and a delayed renewal process, representations of the expected length of an inspection interval and related inequalities in terms of covariances are shown. Datasets of eruption times of Beehive Geyser and Riverside Geyser in Yellowstone National Park, as well as several distributional examples, illustrate the findings. [ABSTRACT FROM AUTHOR]

In the past century, most eruptions of Steamboat Geyser in Yellowstone National Park's Norris Geyser Basin were mainly clustered in three episodes: 1961–1969, 1982–1984, and ongoing since 2018. These eruptive episodes resulted in extensive disturbance to surrounding trees. To characterize tree response over time as an indicator of geyser activity adjustments to climate variability, aerial and ground images were analyzed to document changes in tree coverage around the geyser since 1954. Radiocarbon dating of silicified tree remnants from within 14 m of the geyser vent was used to examine geyser response to possible variations in decadal to centennial precipitation patterns. We searched for atypical or absent growth rings in cores from live trees in years associated with large geyser eruptions. Photographs indicate that active eruptive phases have adversely affected trees up to 30 m from the vent, primarily in the dominant downwind direction. Radiocarbon dates indicate that the geyser formed before 1878, in contrast to the birthdate reported in historical documents. Further, the ages of the silicified trees cluster within three episodes that are temporally correlated with periods of relative drought in the Yellowstone region during the 15th–17th centuries. The discontinuous growth of trees around the geyser suggests that changes in eruptive patterns occur in response to decadal to multidecadal droughts. This inference is supported by the lack of silicified specimens with more than 20 annual rings and by the existence of atypical or missing rings in live trees during periods of extended geyser activity. Plain Language Summary: Steamboat Geyser, in Yellowstone National Park's Norris Geyser Basin, has the tallest eruptions among the world's active geysers. To examine whether eruptions impact trees in the vicinity of the geyser, we analyzed aerial photos acquired since 1954 which indicate that prior periods of frequent eruptions have adversely affected trees up to 30 m from the vent, primarily in the dominant wind direction. To examine if the limited availability of water may have caused the geyser to stop erupting in past centuries, we dated silicified tree remnants with radiocarbon. Results suggest that trees were growing near Steamboat during three periods when the geyser was not erupting because of prolonged droughts in the Yellowstone region during the 15th–17th centuries. This inference is supported by observations that none of the silicified tree specimens had more than 20 annual rings, implying that the trees did not grow for long periods, and by the presence of atypical or missing rings in live trees during periods of geyser activity. Key Points: Aerial photos indicate that recent eruptive phases of Steamboat Geyser have adversely impacted trees up to 30 m from the vent14C dates of silicified trees cluster in three periods that temporally correlate with regional droughts during the 15th–17th centuriesAtypical or absent tree‐rings suggest that prolonged eruption episodes impacted tree growth around Steamboat Geyser [ABSTRACT FROM AUTHOR]

This article, titled "Science Is for Questions," is a poem written by Rebecca Kai Dotlich. The poem explores the various aspects of science, such as the study of stars, rocks, soil, and natural phenomena like hurricanes and earthquakes. It emphasizes the wide range of subjects that science encompasses, including trees, butterflies, mountains, and transportation. The poem encourages readers to question and explore the world around them. The article also provides suggestions for further exploration and engagement with science, such as setting up a science table in the classroom and encouraging students to write about their observations and thoughts. The author of the article, Amy Ludwig VanDerwater, is an author and teacher, while A. T. Baron is a children's book author, illustrator, and zoologist. [Extracted from the article]

Geyser and volcano monitoring suffer from temporal, geographic, and instrumental biases. We present a recording bias identified through multiyear monitoring of Steamboat Geyser in Yellowstone National Park, USA. Eruptions of Steamboat are the tallest of any geyser in the world and they produce broadband signals at two nearby stations in the Yellowstone National Park Seismograph Network. In winter, we observe lower eruption signal amplitudes at these seismometers. Instead of a source effect, we find that environmental conditions affect the recorded signals. Lower amplitudes for 23–45 Hz frequencies are correlated with greater snow depths at the station 340 m away from Steamboat, and we calculate an energy attenuation coefficient of 0.21 ± 0.01 dB per cm of snow. More long‐term monitoring is needed at geysers to track changes over time and identify recording biases that may be missed during short, sporadic studies. Plain Language Summary: What we learn about geysers and volcanoes depends on when, where, and how we are able to monitor them. Here we present a case study of how seasonal changes affect data recorded on a seismometer, which is an instrument that measures ground motion. The world's tallest geyser, Steamboat Geyser in Yellowstone National Park, has intense eruptions that eject a mixture of water and steam. The eruptions are powerful enough to cause tiny ground motions from sound waves that begin in the air and then transfer into the ground. In the winter, we see smaller ground motions at two nearby seismometers. This might imply that Steamboat's eruptions are weaker in the winter; however, winter in Yellowstone comes with snow, and snow is good at absorbing sound wave energy. We find that smaller ground motions occur when snow depths are greater, and that the strength of ground motions should not be used to directly compare eruption intensity. Few geysers around the world are monitored with scientific equipment for long periods of time. Our result highlights the need for more of this type of monitoring so that we can identify biases that may be missed during shorter investigations. Key Points: Seismic signals from Steamboat Geyser eruptions contain ground‐coupled airwaves at distances up to 2.2 kmSnow dampens airwave arrivals leading to lower apparent signal amplitudes in winterInterpretation of eruption signals at both geysers and volcanoes should take changing environmental factors into account [ABSTRACT FROM AUTHOR]

The geyser phenomenon seriously threatens the safe operation of deep tunnel drainage systems and drop shaft structural safety. To simulate the geyser process in a baffle-drop shaft, a 1:50 scale model test system was used to research the response relationship between the geyser mechanism and test parameters such as water depth, inlet pressure, and inlet volume. The results show that the pressure in a baffle-drop shaft fluctuates sharply during the geyser process. This is caused by the release of a high-pressure air mass, and high-speed movement of the air–water mixture causes a local pressure imbalance in the drop shaft. A prediction formula for the maximum geyser height of a baffle-drop shaft was established by a multiple linear regression model. Geyser occurrence conditions for the baffle-drop shaft were proposed combined with the response relationship between different influence variables and geyser intensity. Except for the inlet pressure, submerged state of the baffles, and measured location, the hydrodynamic load on the bottom of the baffles is also related to the randomness of the air–water mixture jetted on the baffle bottom. The maximum hydrodynamic load on the baffle bottom during the geyser is 10 times the hydrodynamic load on the baffle surface under normal discharge conditions. This research provides a theoretical reference for the structural design and safe operation of baffle-drop shafts. [ABSTRACT FROM AUTHOR]

From April to July 2021, West Crater at Iwo-Yama, Kirishima Volcanic Complex, Japan, was repeatedly filled with hydrothermal water and subsequently evacuated. The overall cycle lasted 14–70 h, and the course of a single cycle followed this sequence of phases: (i) steam effusion disappeared 20–40 min before hydrothermal water discharge; (ii) hydrothermal water discharge occurred, generating a hydrothermal water pool; (iii) steam effusion resumed and gradually increased; and (iv) drain-back (evacuation) of the hydrothermal water occurred 1–1.5 h before the onset of the next hydrothermal water discharge. We used multi-parametric observations (optical camera, thermometer, electric self-potential (SP) electrodes, seismometer, acoustic sensor, and tiltmeter) to investigate the cause of the cyclic hydrothermal water discharge. A change in SP data occurred approximately 2 h before the onset of hydrothermal water discharge. However, the change in SP was small when hydrothermal water discharge did not occur. The temporal change in SP is inferred to have been caused by groundwater flow through the region below West Crater, implying that groundwater flow was occurring 2 h before hydrothermal water discharge. The polarity of SP change suggests that groundwater flowed toward the region underlying the vents. Seismic signals in the frequency range of < 20 Hz decreased 15–45 min after the onset of change in SP. This seismic signal pattern is inferred to have been caused by bubble activity in boiling fluid. We interpret that the inflow of cold groundwater inhibited boiling activity in the conduit, which in turn caused the cessation of both steam effusion and seismic activity. SP data suggest that the inflow of cold groundwater gradually decreased before hydrothermal water discharge. Pressurization sufficient to force the water in the upper part of the conduit to ascend could have built up in the lower part of the conduit owing to a decrease in the input of groundwater into the upper part of the conduit and the continuing supply of steam bubbles and hot water. This increase in pressure finally led to hydrothermal water discharge at the surface. We suggest that the inflow of cold groundwater into the geyser conduit was the key control on the occurrence and cyclicity of hydrothermal water discharge in West Crater at Iwo-Yama. [ABSTRACT FROM AUTHOR]

Transient flows in stormwater systems can lead to damaging and dangerous operational conditions, as exemplified by geysering events created by the uncontrolled release of entrapped air pockets. Extreme rain and associated rapid inflows may result in air pocket entrapment, which causes significant changes in flow conditions and potentially geysering. Stormwater geysers have been studied in different experimental and numerical modeling studies, as well as from limited data gathered within real systems. However, there is still no complete understanding of geysering events, as stormwater system geometries vary considerably. Most past studies involved releasing air from an intermediate shaft, in which a significant fraction of the entrapped air may bypass the release. This work advances the understanding of geysering by considering uncontrolled air release through an upstream shaft or manhole. In such cases, the entire air pocket is released upon reaching the shaft, worsening the occurrence of geysering. Pressure and water level measurements were performed for various combinations of initial water pressure, trapped air pocket volume, and vertical shaft geometries, indicating the higher severity of these geysering events. The results obtained also corroborate previous studies in that the measured pressure heads were lower than the grade elevation. Future studies should include larger-scale testing and the representation of this geometry using CFD. [ABSTRACT FROM AUTHOR]

Liquefied petroleum gas on combustion with deficient oxygen produces toxic carbon monoxide. It is used as a fuel to heat water in gas geysers. Here, we report a fatal case of carbon monoxide poisoning resulting from the usage of gas water heater. A 24‑year‑old female had gone to take bath in a bathroom where a gas geyser was installed to heat the water. As she did not come out of the bathroom even after more than an hour, the door was broken down by the relatives and she was found dead. Cherry red postmortem hypostasis, congested and edematous pinkish lungs, and cerebral edema were salient autopsy findings. Carboxyhemoglobin was quantified in blood to 76.55%. The cause of death was attributed to carbon monoxide poisoning; accidental in manner. This case highlights the hazards of using a gas geyser in an ill‑ventilated bathroom. [ABSTRACT FROM AUTHOR]

Storm sewer systems may experience storm geysers, raising concerns about public safety. A thorough understanding of the influential factors of the geysers is essential yet insufficiently investigated in the literature. A transient three-dimensional (3D) computational fluid dynamics model incorporating the volume of fluid method is used to investigate the geyser formation mechanism and hydrodynamics. An air pocket in a pressurized pipe travels with water past a vertical shaft, producing an air-releasing geyser and, subsequently, a rapid-filling geyser. If the air pocket in the pipe is too small or if it moves too quickly, a hybrid geyser might be set off when the air-releasing and rapid-filling geysers overlap. A hybrid geyser has unique properties since it combines an air-releasing geyser and a rapid-filling geyser. The presence of hybrid geysers lowers the height of air-releasing and rapid-filling geysers. Equations are proposed for predicting the heights of the geysers with errors of about 15%. The height of the air-releasing geyser increases with the water level in the shaft. As the pressure difference between the two ends of the pipe reduces, the height of the rapid-filling geyser increases. The vertical shaft diameter has little influence on rapid-filling geysers, while a small diameter often results in high air-releasing geysers. The effect on the height of both kinds of geysers is negligible when the air pocket volume is large enough. The findings can be used for designing storm geyser mitigation measures. [ABSTRACT FROM AUTHOR]

Entrapped air pockets reduce flood conveying capacity of a surcharged drainage tunnel, and could be released explosively as geysers from vertical dropshafts. Nevertheless, the impact of dropshaft inflow on air pocket expulsion has hitherto not been fully understood. In this work, experiments was performed on a simplified drainage system consisting of a dropshaft with inflow. An air pocket was introduced into the tunnel; its dynamics in the dropshaft was measured with a high speed camera and pressure transducers. A heuristic analysis on the kinematics of the air pocket showed that when the dropshaft inflow is greater than a critical flow dependent on the dropshaft diameter, the increased compression leads to stronger air pocket expulsion, as spewing and/or ejection of air-water mixture. Observed occurrence of the phenomena generally agrees with the prediction. [ABSTRACT FROM AUTHOR]

Red geysers are a specific type of quiescent galaxy, denoted by twin jets emerging from their galactic centres. These bisymmetric jets possibly inject energy and heat into the surrounding material, effectively suppressing star formation by stabilizing cool gas. In order to confirm the presence and evolutionary consequences of these jets, this paper discusses the scaling, stacking, and conversion of 21-cm H  i flux data sourced from the H  i -MaNGA survey into H  i gas-to-stellar mass (G/S) spectra. Our samples were dominated by non-detections, or galaxies with weak H  i signals, and consequently by H  i upper limits. The stacking technique discussed successfully resolved emission features in both the red geyser G/S spectrum and the control sample G/S spectrum. From these stacked spectra, we find that on average, red geyser galaxies have G/S of 0.086 ± 0.011 (random) + 0.029 (systematic), while non-red geyser galaxies of similar stellar mass have a G/S ratio of 0.039 ± 0.018 (random) + 0.013 (systematic). Therefore, we find no statistically significant evidence that the H  i content of red geysers is different from the general quiescent population. [ABSTRACT FROM AUTHOR]

Siliceous spicules are micro‐laminated geyserite deposits, or micro‐stromatolites, found around high temperature hot‐springs and geysers, associated with intermittent splashes of water. Understanding conditions of formation of these structures will give insights of critical parameters involved in prebiotic environments and early life. We provide a new data set around two geysers from the El Tatio hydrothermal field, Atacama Desert, Chile, a modern analogue for habitable environments on early Earth and Mars. Small spicules (<5 mm diameter) dominate in the near vent areas, whereas larger spicules (>5 mm diameter) form complex columnar structures in the distal vent (>0.3 m distance from the vent). Hydrodynamics, eruption periodicity, and environmental conditions modulate the temperature and cooling patterns around vents. During geyser eruptions, the temperature of water reaching the ground decreases with the distance from the vent. Cooling is stronger during the evenings, due to strong winds and cold air temperature. Rapid water cooling drives supersaturation of amorphous silica, and therefore precipitation rates increase significantly with distance from the vent. Cooling also controls changes in the bacterial communities, from thin filaments <1 μm diameter predominating closer to the vent, to 1–2 μm diameter filaments in the distal vent. Changes in the silica precipitation rate and biota may control the growth of spicules and the transition to columns. Estimated precipitation rates of silica provide a first approximation of the longevity of these structures and the timing for the formation of internal laminations. Microlamination will form in year time‐scales closer to the vent, and weeks farther from the vent. Key Points: Precipitation rates of silica around the geyser increase with the distance from the ventStrong daily changes in air temperature and wind speed modulate the precipitation rates of silica at El TatioSpicule size and internal lamination increase farther away from the vent due to change in cooling and precipitation rates [ABSTRACT FROM AUTHOR]

Water injection in geothermal areas is the preferential strategy to sustain the natural production of geothermal resources. In this context, monitoring microearthquakes is a fundamental tool to track changes in the reservoirs in terms of soil composition, response to injections, and resource exploitation with space and time. Therefore, refined source characterization is crucial to better estimate the size, source mechanism, and rupture process of microearthquakes, as they are possibly related to industrial activities, and to identify any potential variation in the background seismicity. Standard approaches for source parameter estimation are ordinarily based on the modelling of Fourier displacement spectra and its characteristic parameters: the low-frequency spectral level and corner frequency. Here, we apply an innovative time domain technique that uses the curves of P-wave amplitude vs. time along the seismogram. This methodology allows estimation of seismic moment, source radius, and stress release from the plateau level and the corner time of the average logarithm of P-wave displacement versus time with the assumption of a triangular moment rate function, uniform rupture speed, and a constant/frequency-independent Q-factor. In the current paper, this time domain methodology is implemented on a selected catalog of microearthquakes consisting of 83 events with a moment magnitude ranging between 1.0 and 1.5 that occurred during a 7-year period (2007–2014) of fluid extraction/injection around Prati-9 and Prati-29 wells at The Geysers geothermal field. The results show that the time domain technique provides accurate seismic moment (moment magnitude) and rupture duration/radius estimates of microearthquakes down to the explored limit (M 1) while accounting for the anelastic attenuation effect in the radiated high-frequency wavefield. The retrieved source radius vs. moment scaling is consistent with a self-similar, constant stress drop scaling model, which proves an appropriate attenuation correction and the validity of the assumed, triangular moment rate function for microearthquake ruptures. Two alternative mechanical models are proposed to explain the observed difference (about two orders of magnitude) in the retrieved average stress release estimates between the time and frequency domain methods. We argue that the two quantities may not refer to the same physical quantity representing the stress release of earthquake ruptures. Either the smaller stress release values from the time domain method may indicate a larger fracture area (by a factor of 20) radiating the observed P-waveforms than the one estimated from the corner frequencies, or the frequency domain estimate is a proxy for dynamic stress release while the time domain is more representative of the static release. The latter is associated with a much lower dynamic friction value than static friction value at the fault during the rupture process. [ABSTRACT FROM AUTHOR]

Yellowstone National Park (YNP) is home to roughly 500 geysers, making it the most concentrated geyser field in the world. Recent studies exploring the mechanics of geyser eruptions utilizing laboratory models were limited by a lack of knowledge of the subsurface geometry of the geyser features. This study presents results from active hydrogeophysical surveys, including ground penetrating radar, nuclear magnetic resonance (NMR), seismic refraction, electrical resistivity tomography, and transient electromagnetics to image subsurface geyser structure and constrain the geophysical response of the reservoir structure of Spouter Geyser, Yellowstone National Park. Previous geophysical studies on similar geyser systems in Yellowstone characterize the hydrothermal reservoir that supplies the geyser with hydrothermal fluids and vapors as high porosity, low density structures. Whereas our imaging highlights the hydrothermal conduits and reservoir as high resistivity and high velocity structures, interpreted as silica precipitate decreasing the porosity and increasing the bulk modulus (i.e., from unconsolidated media to semi/fully consolidated). Ground penetrating radar identifies sinter thickness around the geyser, NMR provides porosity measurements of the geyser reservoir, and transient electromagnetics maps the depth to the Biscuit Basin Rhyolite bedrock throughout the field site. Electrical resistivity tomography and seismic refraction image the shallow geyser conduit structures to ∼15 m depth and establish the extent of the geyser hydrothermal reservoir structure. Furthermore, a spatial correlation of the electrical resistivity and seismic velocity results establishes the interpreted hydrothermal geyser reservoir as a high resistivity, high velocity structure located to the northeast of Spouter Geyser at depths greater than 15 m. Plain Language Summary: The dynamics of geyser eruptions are uncertain. Much of this uncertainty stems from a lack of knowledge of their subsurface structure. Therefore, to better understand geyser eruption dynamics, we must first establish the subsurface structure of geysers and their associated hydrothermal geyser reservoirs that supply the erupted hydrothermal fluids and vapors. Geophysical imaging provides an opportunity to image these structures, but active geophysical methods have not been extensively explored for this application. In this study, we use various active geophysical methods to (a) constrain the characteristics of the structure and (b) better understand the subsurface geometry of Spouter Geyser (YNP) and its hydrothermal reservoir. We find that Spouter Geyser's structure and its reservoir have high electrical resistivity and seismic velocity responses, indicative of low porosity and highly cohesive characteristics due to silica precipitate from hydrothermal fluids. We also find that Spouter Geyser's subsurface geometry consists of silica‐lined conduits that extend 15 m to a broad, laterally offset geyser hydrothermal reservoir structure. With the knowledge of the characteristics and geometry of Spouter Geyser and its hydrothermal reservoir, an additional study (Geyser Dynamics II) is better positioned to explore the dynamics of geyser eruptions with active geophysical methods. Key Points: Geophysical results reveal a laterally offset, low porosity and highly consolidated geyser reservoir structure at Spouter GeyserDistinct vertical conduit structures extending to the hydrothermal geyser reservoir at 15 m depth are interpreted at Spouter GeyserVelocity and resistivity distribution characterize Spouter Geyser's reservoir structure as high velocity‐high resistivity [ABSTRACT FROM AUTHOR]

Geysers are unique hydrothermal features, requiring specific geometry, fluid, and vapor input, and heat to produce eruptions. In a geyser eruption, the decompression of superheated hydrothermal fluids results in a conversion of thermal to kinetic energy. Recent studies conclude that a laterally offset cavity structure (bubble trap) plays an integral role in the geyser eruption process. In this second study of Spouter Geyser, Yellowstone National Park (YNP), we build on the geyser structure developed in the first publication and explore how structural components, such as the bubble trap, control eruption dynamics. We utilize time‐lapse electrical resistivity tomography (ERT) and transient electromagnetics (TEM) geophysical methods to track changes in the saturation of conductive hydrothermal fluid and resistive vapor through the eruption cycle. Additionally, we use pressure‐temperature transducer data to measure eruption and recharge durations over the past 23 years at Spouter Geyser, identifying long‐period trends in geyser behavior. The geophysics results support the bubble trap model, capturing an increase in resistivity in the bubble trap structure during the recharge phase interpreted as a vapor saturation increase. The TEM also captures a resistivity increase in the 20–30 m depth interval during the eruption phase, interpreted as a vapor‐dominated "flash eruption zone" where the superheated hydrothermal fluids flash into steam and drive fluid out of this zone during the eruption. From the temperature time‐series detailing 23 years of eruption and recharge durations, we find that eruption durations have remained constant at ∼2 hr while recharge durations have decreased linearly at 6.6 min/year. Plain Language Summary: Current geyser eruption models include a bubble trap structure, a laterally offset, subsurface cavity that pressurizes with hydrothermal fluid and vapor before an eruption. Hydrothermal fluid conducts electrical current more efficiently than hydrothermal vapors, and thus the two phases have different electrical resistivity properties, a measurable geophysical parameter. Here, we pioneer the application of active, time‐lapse electrical and electromagnetic geophysical methods, sensitive to the subsurface electrical resistivity properties, to track hydrothermal fluid and vapor through a geyser system at Spouter Geyser, Yellowstone National Park. Through this, we expand on conclusions of Spouter Geyser's structure (Geyser Dynamics I) by investigating the movement of hydrothermal fluids and vapors to contribute to the understanding of geyser eruption dynamics. We find that electrical resistivity at the top of the geyser hydrothermal reservoir increases while the geyser is not erupting, indicative of vapor buildup in a bubble trap structure. We also find that electrical resistivity increases in a section of the geyser hydrothermal reservoir during the eruption, interpreted as hydrothermal vapors flashing to steam and driving fluids to the surface. Finally, we investigate eruption durations over the past two decades at Spouter Geyser, revealing constant average eruption durations but an increase in eruption frequency. Key Points: Time‐lapse electrical and electromagnetic methods track changes in hydrothermal fluid and vapor saturations in Spouter Geyser's structureTime‐lapse geophysics informs a conceptual model of eruption dynamics at Spouter Geyser that supports the bubble trap geyser modelA 6.6 min/year decrease in Spouter Geyser's average recharge duration over the last 23 years offers insight into long‐duration behavior [ABSTRACT FROM AUTHOR]

The article explores views of several visitors of the Yellowstone National Park on the park's geysers, waterfalls, gurgling mud pots, and animals. Several visitor's whose views are expressed include Frank Carpenter, who compare the park's Upper Geyser Basin with Wonderland; W. E. Strong, who found grandest spectacle in the park; and Gary Ferguson, who mentions the beauty of Geyser Land far superior to anything.

Over the south pole of Enceladus, an icy moon of Saturn, geysers eject water into space in a striped pattern, making Enceladus one of the most attractive destinations in the search for extraterrestrial life. We explore the ocean dynamics and tracer/heat transport associated with geysers as a function of the assumed salinity of the ocean and various core-shell heat partitions and bottom heating patterns. We find that, even if heating is concentrated into a narrow band on the seafloor directly beneath the south pole, the warm fluid becomes quickly mixed with its surroundings due to baroclinic instability. The warming signal beneath the ice is diffuse and insufficient to prevent the geyser from freezing over. Instead, if heating is assumed to be local to the geyser (either generated in the ice due to tidal dissipation or friction or generated in the ocean as water flushes in/out of the geyser slot under tidal forcing), geyser can be sustained. In this case, the upper ocean beneath the ice becomes stably stratified creating a barrier to vertical communication, leading to transit time-scales from the core to the ice shell of hundreds of years in contrast to purported transit time-scales of weeks to months. [ABSTRACT FROM AUTHOR]

Geysers are among the most fascinating geological features on Earth. Yet, little is still known about their hydrogeological structure at depth. To shed light on the spatial relationships between the vertical conduits and the aquifers feeding them, we conducted a 3D geoelectrical campaign in the Haukadalur hydrothermal field, Iceland. We deployed 24 Iris Fullwavers across the hydrothermal field and inverted resistivity and chargeability measurements. Additionally, we measured temperature variations inside Strokkur and Great Geysir geysers showing temperature fluctuations pointing out the oscillatory behavior that characterizes the geysering cycle of the geysers. By combining a semi‐quantitative temperature distribution of the thermal springs across the hydrothermal field with the inversion of the geoelectrical data, we highlight the control that extensional tectonics have on the distribution of fluids across the hydrothermal field. We also point out the occurrence of a common deep groundwater reservoir feeding the hydrothermal centers. Induced polarization data show that the geysers are fed by sub‐vertical water‐filled fracture zones. The geysers are found at the margins of highly resistive regions where we speculate boiling groundwater and vapor is found. Our proposed model suggests that local waters feeding the main groundwater reservoir downwell from the nearby region and then convect upwards, phase transitioning into vapor at about 200 m depth. From here, fluids flow toward the surface through pipes cutting a highly pressurized and hot system. This study shows to the best of our knowledge the first full 3D tomographic image of a hydrothermal field hosting geysers. Plain Language Summary: Geysers are erupting jets of boiling waters. Despite being one of the most fascinating geological processes on Earth, little is still known about their plumbing system at depth. To investigate the 3D geological structure of the Haukadalur hydrothermal field in Iceland, we injected electrical current into the ground and recorded the voltage across the hydrothermal field caused by such an injection. The measured voltage is proportional to the resistive structure of the hydrothermal field where the roots of the Strokkur and Great Geysir geysers are located. We also lowered thermometers into the geyser's conduits to measure temperature variations during geysering cycles. Our multidisciplinary study has shown the occurrence of a fault system along which the hydrothermal fluids are focused. We believe that the shallow hydrothermal springs are fed by a common reservoir at depth but we could not infer whether the two main geysers share the same reservoir. To the best of our knowledge our study shows the first 3D image of the structure of a geyser field. Key Points: 3D resistive structure of the geyser‐hosting Haukadalur hydrothermal fieldVapor‐saturated boiling reservoirs feeding geysers and hydrothermal pondsFluid flow controlled by local tectonics [ABSTRACT FROM AUTHOR]

Red Geysers are quiescent galaxies with galactic scale ionized outflows, likely due to low-luminosity active galactic nuclei (AGN). We used Gemini GMOS-IFU observations of the inner ∼1–3 kpc of nine Red Geysers selected from the MaNGA survey to study the gas ionization and kinematics. The emission-line ratios suggest the presence of Seyfert/LINER (Low Ionization Nuclear Emission Region) nuclei in all sources. Two galaxies show  Hα equivalent width ( Hα EW) larger than 3 Å (indicative of AGN ionization) within an aperture 2 |${_{.}^{\prime\prime}}$| 5 of diameter (1.3–3.7 kpc at the distance of galaxies) for MaNGA data, while with the higher resolution GMOS data, four galaxies present  Hα EW>3 Å within an aperture equal to the angular resolution (0.3–0.9 kpc). For two objects with GMOS-IFU data, the  Hα EW is lower than 3 Å but larger than 1.5 Å, most probably due to a faint AGN. The spatially resolved electron density maps show values between 100 and 3000 cm −3 and are consistent with those determined in other studies. The large (MaNGA) and the nuclear scale (GMOS-IFU) gas velocity fields are misaligned, with a kinematic position angle difference between 12° and 60°. The [N  ii ] λ6583 emission-line profiles are asymmetrical, with blue wings on the redshifted side of the velocity field and red wings on the blueshifted side. Our results support previous indications that the gas in Red Geysers is ionized by an AGN, at least in their central region, with the presence of outflows, likely originating in a precessing accretion disc. [ABSTRACT FROM AUTHOR]

A volcanic eruption is usually preceded by seismic precursors, but their interpretation and use for forecasting the eruption onset time remain a challenge. A part of the eruptive processes in open conduits of volcanoes may be similar to those encountered in geysers. Since geysers erupt more often, they are useful sites for testing new forecasting methods. We tested the application of Permutation Entropy (PE) as a robust method to assess the complexity in seismic recordings of the Strokkur geyser, Iceland. Strokkur features several minute‐long eruptive cycles, enabling us to verify in 63 recorded cycles whether PE behaves consistently from one eruption to the next one. We performed synthetic tests to understand the effect of different parameter settings in the PE calculation. Our application to Strokkur shows a distinct, repeating PE pattern consistent with previously identified phases in the eruptive cycle. We find a systematic increase in PE within the last 15 s before the eruption, indicating that an eruption will occur. We quantified the predictive power of PE, showing that PE performs better than seismic signal strength or quiescence when it comes to forecasting eruptions. Plain Language Summary: When a volcano shows the first sign of activity, it is challenging to determine whether and when the actual eruption will occur. Usually, researchers create earthquake lists and locate these events to assess this. However, an alternative and simpler method can be directly applied to continuous seismic data. We tested a method that assesses the complexity of signals. We first created synthetic data to find reasonable parameter settings for this method. While volcanoes do not erupt very often, frequent eruptions at geysers allow us to systematically study and compare several eruptions. We analyzed the continuous record of 63 eruptions of the Strokkur geyser, Iceland. Our results show a distinct pattern that repeats from one eruption to the next one. We also find a clear pattern that indicates about 15 s before the next eruption that an eruption will occur. We show that this method performs better in eruption forecasting than assessing the seismic noise or silence caused by the geyser. Key Points: Permutation Entropy (PE) is a simple tool to assess the complexity of a time seriesWe analyzed the PE evolution for 63 eruptive cycles of Strokkur geyser and found characteristic changes in PE during rechargePE is found to be an useful statistical predictor of the eruption times and highlights the precursor 15 s before eruptions [ABSTRACT FROM AUTHOR]

The present study describes the isolation of an extremely thermophilic bacterium from El Tatio, a geyser field in the high planes of Northern Chile. The thermophile bacterium named Thermus thermophilus strain ET-1 showed 99% identity with T. thermophilus SGO.5JP 17-16 (GenBank accession No. CP002777) by 16S rDNA gene analysis. Morphologically, the cells were non-sporeforming Gram-negative rods that formed colonies with yellow pigmentation. This strain is able to proliferate between 55 and 80 °C with a pH range of 6–10, presenting an optimum growth rate at 80 °C and pH 8. The bacterium produces an extracellular protease activity. Characterization of this activity in a concentrated enzyme preparation revealed that extracellular protease had an optimal enzymatic activity at 80 °C at pH 10, a high thermostability with a half-life at 80 °C of 10 h, indicating that this enzyme can be classified as an alkaline protease. The proteolytic enzyme exhibits great stability towards chelators, divalent ions, organic solvents, and detergents. The enzyme was inhibited by phenylmethylsulfonyl fluoride (PMSF), implying that it was a serine protease. The high thermal and pH stability and the resistance to chelators/detergents suggest that the protease activity from this T. thermophilus. strain could be of interest in biotechnological applications.

1941-2017 period of the Valley of Geysers monitoring (Kamchatka, Kronotsky Reserve) reveals a very dynamic geyser behavior under natural state conditions: significant changes of IBE (interval between eruptions) and power of eruptions, chloride and other chemical components, and preeruption bottomtemperature.Nevertheless, the total deep thermal water discharge remains relatively stable; thus all of the changes are caused by redistribution of the thermal discharge due to giant landslide of June 3, 2007,mudflow of Jan. 3, 2014, and other events of geothermal caprock erosion and water injection into the geothermal reservoir. In some cases, water chemistry and isotope data point to localmeteoric water influx into the geothermal reservoir and geysers conduits. TOUGHREACT V.3 modeling of Velikan geyser chemical history confirms 20% dilution of deep recharge water and CO2 components after 2014. Temperature logging in geysers Velikan (1994, 2007, 2015, 2016, and 2017) and Bolshoy (2015, 2016, and 2017) conduits shows preeruption temperatures below boiling at corresponding hydrostatic pressure, whichmeans partial pressure of CO2 creates gas-lift upflow conditions in geyser conduits. Velikan geyser IBE history explained in terms of gradual CO2 recharge decline (1941-2013), followed by CO2 recharge significant dilution after the mudflow of Jan. 3, 2014, also reshaped geyser conduit and diminished its power.

The Upper Geyser Basin at Yellowstone National Park (Wyoming, USA) harbors the greatest concentration of geysers worldwide. Research suggests that individual geysers are not isolated but rather are hydraulically connected in the subsurface with other geysers and thermal springs. To quantify such connections, we combined techniques from machine learning, causal inference, and dynamical systems to characterize the collective eruptive behavior of a set of 10 geysers over 18 months (April 2007 – September 2008) focusing on geyser‐geyser interactions. Model predictions were up to 15 times more accurate when we sought to predict a geyser's eruption time series based on outflow channel temperatures from the network than based on its own time series alone, suggesting the existence of a complex interconnected subsurface groundwater system. On average, cone‐type geysers had larger impacts on other geysers than did fountain‐type geysers. Similarly, cone‐type geysers were on average more insulated from other geysers. However, substantial unexplained variation remained after considering the cone versus fountain dichotomy. Distance between geysers also affected interactions: nearby geysers had stronger effects on focal geysers than did geysers located farther away. Collectively, results support the hypothesis of geyser interdependence at timescales of 5 min–10 days. Our analyses highlight the existence of quantifiable geyser‐to‐geyser interactions that can be resolved through pairwise and system‐level analyses. These findings emphasize the subsurface interconnectedness of thermal features, provide information relevant to visitor experiences in Yellowstone National Park, and suggest strategies for exploring patterns of interdependence that may exist among other episodic geological phenomena. Plain Language Summary: Are geysers connected to other geysers such that they influence each other's eruptions? To answer this question, we analyzed eruptive temperature data from 10 geysers collected over 18 months in the Upper Geyser Basin at Yellowstone National Park (Wyoming, USA). We used a computational technique called "reservoir computing" to quantify the strength of the pairwise interactions between geysers. We found that that cone‐type geysers have larger impacts on other geysers than do fountain‐type geysers and that cone‐type geysers are more insulated from the effects of other geysers. Predictive accuracy of the outflow temperature from the well‐known Old Faithful Geyser nearly doubled when using this approach, and overall, model predictions were up to 15 times more accurate when we sought to predict a geyser's dynamics from the network than based on its own history alone. These improvements suggest that geysers are not independent and instead reflect the existence of a complex interconnected subsurface groundwater system. Our analyses highlight the existence of quantifiable geyser‐to‐geyser interactions that can be resolved through pairwise and system‐level analyses, and suggest strategies for exploring patterns of interdependence that may exist among other episodic geological phenomena. Key Points: Reservoir computing, a form of machine learning, was used to characterize the collective behavior of 10 Yellowstone geysersNetwork‐level predictions of geyser behavior offered substantial improvements over individual time seriesInter‐geyser distance and geyser morphology helped shape the strength of interconnections among thermal features [ABSTRACT FROM AUTHOR]

Numerical reservoir modeling plays an important role in understanding and predicting the performance of geothermal reservoirs to varying exploitation schemes. In this study, four parameters including thermal breakthrough time, water level and vertical displacement at the production wells and the recoverable energy in the licensed region are selected to assess the potential exploitation schemes. An integrated model combining the simplified 1D geothermal well model and the 3D geothermal reservoir model is developed to simulate the fully coupled thermo-hydro-mechanical (THM) processes in geothermal reservoirs including multiple wells, and the measured surface settlement data in the Geysers geothermal field is used to validate the reasonability and efficiency of the developed modeling method. A case study of the Rongcheng geothermal field, China, is presented to clarify the important role of coupled THM processes in the sustainable exploitation of geothermal resources. The results show that the developed integrated model is a robust simulation tool to understand and predict the performance of city-scale geothermal fields under different patterns of well groups. The production wells may not reach the designed lifetime due to various natural or artificial reasons, so the optimal well patterns should be designed to maximize the recoverable geothermal energy considering the natural properties of geothermal reservoirs. Highlights: Coupled thermo-hydro-mechanical processes are considered in an integrated geothermal reservoir model. Assessment criteria of sustainable exploitation of geothermal resources in the licensed region are defined. The responses of the Rongcheng geothermal field under different patterns of well groups are studied. [ABSTRACT FROM AUTHOR]

The Daggyai sinters in Tibet are known for their Cs‐bearing deposits. To understand the relationship between Cs concentrations and sinter fabrics, variations in fabrics and Cs contents along a temperature gradient from 81 to 43°C associated with the Daggyai Major Geyser are examined herein. The fabrics of sinters vary from stromatolite‐like in the pool margin to palisade with numerous large‐diameter filaments along the overflow apron to diatoms and small‐diameter filaments at the distal end of discharge channel. The large‐diameter filaments are tentatively assigned to Chloroflexi, whereas the filamentous mats found at the pool margin and distal end of discharge channel may have been formed by cyanobacteria. The Cs concentrations are highest in the sinters associated with the cyanobacteria. These results indicate that Cs enrichment may be controlled by the composition and abundance of microbial community. [ABSTRACT FROM AUTHOR]

Geyser eruption is one of the most popular signature attractions at the Yellowstone National Park. The interdependence of geyser eruptions and impacts of covariates are of interest to researchers in geyser studies. In this paper, we propose a parametric covariate-adjusted recurrent event model for estimating the eruption gap time. We describe a general bivariate recurrent event process, where a bivariate lognormal distribution and a Gumbel copula with different marginal distributions are used to model an interdependent dual-type event system. The maximum likelihood approach is used to estimate model parameters. The proposed method is applied to analyzing the Yellowstone geyser eruption data for a bivariate geyser system and offers a deeper understanding of the event occurrence mechanism of individual events as well as the system as a whole. A comprehensive simulation study is conducted to evaluate the performance of the proposed method. [ABSTRACT FROM AUTHOR]

CO2‐driven cold‐water geysers periodically ejecting cold water are rare. Although coalescence and expansion of ascending CO2 bubbles can explain the eruption process, the triggering conditions and eruption cycle remain unclear. To clarify the triggering conditions, hydrostatic pressure in the well was decreased by pumping to induce eruptions. All four pumping tests successfully induced eruptions by decreasing the pressure of ∼104 Pa. In the absence of artificial perturbations, similar reductions in pressure were observed during the intervals between two consecutive eruptions (IBEs). During IBE, the atmospheric pressure (Pair) and temperature (Tair) controlled the generation of the CO2 bubbles which directly induced the pressure reduction in the well. Especially under the persistent low Pair and high Tair, the length of IBE showed a minimum value of 3.90 hr during field observations. We suggest that the atmospheric perturbations are the causes of the changes in geyser periodicity, given consistent geological and hydraulic conditions. Plain Language Summary: CO2‐driven cold‐water geysers are formed by ascent of CO2 bubbles through vertical migration paths such as man‐made wells drilled into natural CO2 reservoirs. As one possible CO2 leakage pattern from geologic carbon sequestration, CO2‐driven cold‐water geysers have drawn attention in recent years. This study characterized the process based on in situ measurements of the Tenmile well located in the southern Green River area, Utah. To clarify the eruption process, multiple consecutive geyser eruptions were artificially induced to define the triggering conditions. This study concluded that a slight decrease in pressure triggers geyser eruption and atmospheric perturbations cause slight pressure changes during intervals between eruptions within the natural conditions. The eruption periodicity is controlled by the atmospheric conditions over the short term, given consistent geological and hydraulic conditions. Key Points: We found the triggering pressures for vigorous geyser eruptions by pumping tests (artificial pressure reductions) in the fieldThe decreases in pressure until the triggering pressure were similar to those caused by changes in atmospheric conditionsGeyser eruption periodicity is affected by atmospheric perturbations, given consistent geological and hydraulic conditions [ABSTRACT FROM AUTHOR]