Although many deep-seated magma reservoirs have been detected beneath active volcanic systems in Iceland in recent decades, none were detected beneath the 5 volcanic systems on the Reykjanes Peninsula (RP) before the year 2020. This area, close to Iceland’s capital Reykjavik, was subject to an unrest period with numerous earthquakes, beginning in December 2019. Using this abundant seismicity to produce tomographic images of the RP, we discovered a high Vp/Vs anomaly below the volcanic system of Fagradalsfjall – the smallest of the 5 systems on the RP. This anomaly is clear on images as early as May 2020 and we interpret it as the top part of the source reservoir of the Fagradalsfjall Volcanic System, which now supplies magma to the eruption that started there on 19 March 2021. From the tomographic images, we infer that the roof of the reservoir is at ~10 km below the surface of the volcanic system, but the reservoir itself extends much deeper. We interpret the results as magma accumulation in the upper part of the reservoir at least by May 2020, and probably earlier, resulting in a slight magma-pressure increase and doming of the reservoir roof. The associated stress changes in the roof triggered several earthquake swarms throughout 2020 and into early 2021. Within the part of the roof closest to the reservoir (between 9-12 km depth) 40 earthquakes occurred during 2020. This number doubled again between 1 January and 19 March 2021, when the eruption began. We interpret the preceding earthquake swarm, which began on 24 February 2021 with an earthquake of M5.6, as being associated with the rupture of the roof of the reservoir and dike-segment injection. We interpret the increased activity on the 14th of March, and its location, as a second rupture and a new dike-segment injection which ultimately lead to the eruption, which is still on-going at the time of writing. The reservoir is the first one detected below any of the volcanic systems on the RP. Furthermore, the reservoir supplies magma to the first eruption on the RP for nearly 800 years and the first eruption in Fagradalsfjall for some 6000 years.

A doublet earthquakes event including two main shocks with a magnitude larger than Mw 6.0 occurred on 1 July, 2022 in the Zagros fold-and-thrust belt, southeast Iran. The coseismic InSAR deformation field shows that this event caused significant surface uplift due to fault-related folding in the seismic zone. The estimated preferred faulting model suggests that a higher dip angle fault (maximum slip of ~1.1 m), and an overlying gentle dipping fault (maximum slip of ~1.2 m) within the Bandar-e-Lengeh Anticline, are responsible for the first and second main shocks, respectively. The calculated Coulomb failure stress change suggests that the first main shock has a significantly positive triggering effect in the second main shock. The coseismic deformation due to this doublet earthquakes is equal to the accumulated interseismic deformation for the past ~104 years. Finally, the salt diapir activity may affect the generation of the earthquake in the seismic zone.

At thermodynamic equilibrium, gas hydrates are arranged in the pore space of host sediments to minimize free energy, including the energy of interfaces. Through an analogy with frozen soil, we show that free energy minimization in hydrate-bearing sediments requires the presence of a water film of finite thickness separating hydrate from the sediment grains. The thickness of this premelted layer may be predicted from a balance of intermolecular forces acting across the film. Temperature and porewater salinity are the strongest determiners of premelted layer thickness. We show that, at temperatures and salinities typical of the subsurface or commonly used in laboratory investigations of hydrate-bearing porous media, the premelted layer varies in thickness from microns to sub-nanometer, with thicker layers corresponding to lower salinities and/or higher temperatures. Balance of intermolecular forces predicts that hydrate will be completely nonwetting on hydrophilic surfaces, including silica. We also show that flow through premelted layers may be a significant component of the permeability of hydrate-bearing sediments, particularly at moderate to high hydrate saturation (>60%); and that the electrical conductivity of the premelted layer at needs to be accounted for in assessments of hydrate abundance from subsurface resistivity logs. This work highlights the importance of considering premelted layers when predicting the effects of hydrate on sediment properties.

One of Venus’ most enigmatic landforms is Baltis Vallis, the longest observed channel on the surface (~7000 km long). Topographic conformity analysis shows that Baltis Vallis was modified over most of its observed wavelengths. Since the source location of Baltis Vallis is not well constrained, we analyze in both flow directions. For the commonly used northern source, topography across all wavelengths appears to be created after Baltis Vallis. However, for the southern source, topographic components with wavelengths longer than ~1900 km might have previously existed. Fourier analysis reveals three characteristic wavelengths, ~110-235 km, ~640±25 km and ~3500±1200 km. The shortest corresponds to deformation belts that cross Venus’ low plains, while the medium currently lacks an explanation. The longest is plausibly associated with the wavelength of dynamic uplift of the crust by mantle plumes. Higher resolution observations provided by the VERITAS mission can help resolve the source location of Baltis Vallis.

Physical processes involved in the ascent of naturally seeped oil from the seafloor and its persistence as a slick are considered. Simplified, physics-based models are developed, drawing in part from the extensive literature concerned with anthropogenic releases of oil at sea. The first model calculates the ascent of oil droplets or oil-coated gas bubbles as they ascend to the sea surface from the seep source. The second model calculates slick longevity as a function of the effect of wind-driven breaking waves. Both models have simplified inputs and algorithms making them suitable for Monte Carlo-type analysis. Using the oil ascent model, we find that slicks from shallower seeps are offset farther relative to their water depth than those from deeper sources. The slick longevity model reveals four growth modes for seepage slicks: persistent (low wind speeds), ephemeral (high wind speeds), reset (all slicks are cleared from an area by high wind speeds), and aging (slick growth after a reset). A year’s worth of modeled winds from the Gulf of Mexico indicate average slick ages of ~ 12 hours. Taking account of the expected oil release duration implied by slick recurrences yields average slick longevities for high recurrence seeps of ~6.5 hours and ~ 5 hours for low recurrence seeps. Seep flux estimates that include the length of individual slicks and the constraints of local currents and wind implicitly take into account the impact of wind-speed history. Those that assume a slick age should be re-evaluated in light of the current findings.

The current study aimed at assessing the capabilities of five machine learning models in term of mapping tungsten polymetallic prospectivity in the Gannan region of China. The five models include logistic regression (LR), support vector machine (SVM), random forest (RF), convolutional neural network (CNN), and light gradient boosting machine (LGBM) models. Geochemical, lithostratigraphic, and structural datasets were used to generate 16 evidential maps, which were integrated into the machine learning models. Tungsten polymetallic deposits were randomly separated into two parts: 80% for training and 20% for validating. Performances of the models were evaluated through receiver operating characteristic (ROC) and K-fold cross validation, with an emphasis on the variable influence within different machine learning methods. The results show that the models are especially sensitive to the chemical elements: Be, Bi, Pb and Cd, implying that these are closely related to tungsten polymetallic mineralization. Compared to other models, the LGBM and CNN models performed best, while the LR model was the most stable. The results also indicated that the CNN model can predict maximum known deposits within a minimum area, based on the prediction-area plot analysis of the five models, while the RF model can capture the most well-known deposits within the smallest study area. Finally, eighteen prospective areas were delineated according to the predicting results of the machine learning models, which will provide important guidance for further tungsten polymetallic exploration and associated studies.

Recent activity has provided new insights into the causes of surface deformation in and around the Yellowstone Caldera, a topic that has been debated since the discovery of caldera-floor uplift more than four decades ago. An episode of unusually rapid uplift (>15 cm/yr) centered near Norris Geyser Basin along the north caldera rim began in late 2013 and continued until a Mw 4.9 earthquake on 30 March 2014; thereafter, uplift abruptly switched to subsidence. Uplift at rates of several cm/yr resumed in 2016 and continued at least through the end of 2018. Modeling of Global Positioning System (GPS) and interferometric synthetic aperture radar (InSAR) data suggests an evolving process of deep magma intrusion during 1996-2001 followed by volatile ascent and accumulation at shallow levels, perhaps as shallow as a few hundred meters depth. The preferred deformation model in which the volatiles accumulated is a shallow uplifted (domed) reservoir. The depth of shallow volatile accumulation appears to have shallowed from the 2014 to the 2016 deformation episode, from 3.2 km depth to 1.8 km depth respectively, and frequent eruptions of Steamboat Geyser since March 2018 might be a surface manifestation of this ongoing process. Hydrothermal explosion features are prominent in the Norris Geyser Basin area, and the apparent shallow nature of the inferred volatile accumulation might represent an increased risk of hydrothermal explosions in the vicinity of Norris Geyser Basin.

Satellite remote sensing is becoming an increasingly essential component of volcano monitoring, especially at little-known and remote volcanoes where in-situ measurements are unavailable and/or impractical. Moreover the synoptic view captured by satellite imagery over volcanoes can benefit hazard monitoring efforts. By monitoring, we mean both following the changing styles and intensities of the eruption once it has started, as well as nowcasting and eventually forecasting the areas potentially threatened by hazardous phenomena in an eruptive scenario. Here we demonstrate how the diversity of remote sensing data over volcanoes and the mutual interconnection between satellite observations and numerical simulations can improve lava flow hazard monitoring in response to effusive eruption. Time-averaged discharge rates (TADRs) obtained from low spatial/high temporal resolution satellite data (e.g. MODIS, SEVIRI) are complemented, compared and fine-tuned with detailed maps of volcanic deposits with the aim of constraining the conversion from satellite-derived radiant heat flux to TADR. Maps of volcanic deposits include the time-varying evolution of lava flow emplacement derived from multispectral satellite data (e.g. EO-ALI, Landsat, Sentinel-2, ASTER), as well as the flow thickness variations, retrieved from the topographic monitoring by using stereo or tri-stereo optical data (e.g. Pléiades, PlanetScope, ASTER). Finally, satellite-derived parameters are used as input and validation tags for the numerical modelling of lava flow scenarios. Here we show how our strategy was successfully applied to several remote volcanoes around the world.

The North American Newark Canyon Formation (~113–98 Ma) presents an opportunity to examine how various terrestrial carbonate facies reflect different aspects of paleoclimate during one of the hottest periods of Earth’s history. We combined carbonate facies analysis with δ13C, δ18O, and Δ47 datasets to assess which palustrine and lacustrine facies preserve stable isotope signals that are most representative of climatic conditions. Type section palustrine facies record the heterogeneity of the original palustrine environment in which they formed. Using the pelmicrite facies that formed in deeper wetlands, we interpret a lower temperature zone (35–40°C) to reflect warm season water temperatures. In contrast, the mottled micrite facies reflects hotter temperatures (36–68°C). These hotter temperatures preserve radiatively heated “bare-skin” temperatures that occurred in a shallow depositional setting. The lower lacustrine unit has been secondarily altered by hydrothermal fluids while the upper lacustrine unit likely preserves primary temperatures and δ18Owater of catchment-integrated precipitation. Based on this investigation, the palustrine pelmicrite and lacustrine micrite are the facies most likely to reflect ambient climate conditions, and therefore, are the best facies to use for paleoclimate interpretations. Average warm season water temperatures of 41.1±3.6°C and 37.8±2.5°C are preserved by the palustrine pelmicrite (~113–112 Ma) and lacustrine micrite (~112–103 Ma), respectively. These data support previous interpretations of the mid-Cretaceous as a hothouse climate. Our study demonstrates the importance of characterizing facies for identifying the data most representative of past climates.

Climate and carbon cycling during the Eocene were complex, as inferred from records of stable isotopes and carbonate accumulation in marine sediment sections. Following a now well-documented early Eocene interval characterized by extreme global warmth and numerous short-term C-cycle perturbations documented in many sediment sections across the world, the ‘warmhouse’ climate state of the middle-late Eocene remains far less studied. In particular, the middle Eocene was punctuated by an event of significant global warming and seafloor carbonate dissolution (Middle Eocene Climate Optimum or MECO, ca. ~40.5 Ma). Over the last decade, studies from multiple sites in the Atlantic have suggested another abrupt and transient (and potentially a hyperthermal) warming event seemingly associated with a C-cycle perturbation at ~41.5 Ma, referred to as the Late Lutetian Thermal Maximum (LLTM). While both MECO and LLTM punctuate the post-EECO long-term cooling, their isotopic expression and duration are fundamentally different. At present, a dearth of continuous middle Eocene chemostratigraphic records limits our understanding of warming events like MECO and especially, the global extent of the LLTM. In this study, we develop an isotope stratigraphy of Lutetian-Bartonian age sediments from three different sites in the southwest Pacific region, two of which were drilled during IODP Expedition 371 in the Tasman Sea and a third that derives from field work in New Caledonia. We identify long-term changes in carbon and oxygen isotope records, possibly related to 405 Ky eccentricity cycles, and identify the stratigraphic expression of the LLTM and MECO. These new middle Eocene chemostratigraphic records from the southwest Pacific help to establish the global nature and relevance of multiple warming events that occurred during the ‘warmhouse’ climatic conditions of middle Eocene and highlight the utility of sedimentary carbon isotopes as a tool for chemostratigraphy and deciphering causes of past global changes.

Mineral compositions are used to infer pressures, temperatures, and timescales of geological processes. The thermodynamic techniques underlying these inferences assume a uniform, constant pressure. Nonetheless, convergent margins generate significant non-hydrostatic (unequal) stresses, violating the uniform pressure assumption and creating uncertainty. Materials scientists F. Larché and J. Cahn derived an equation suitable for non-hydrostatically stressed geologic environments that links stress and equilibrium composition in elastic, multi-component crystals. However, previous works have shown that for binary solid solutions with ideal mixing behavior, hundreds of MPa to GPa-level stresses are required to shift mineral compositions by a few hundredths of a mole fraction, limiting the equation’s applicability. Here, we apply Larché and Cahn’s equation to garnet, clinopyroxene, and plagioclase solid solutions, incorporating for the first time non-ideal mixing behavior and more than two endmembers. We show that non-ideal mixing increases predicted stress-induced composition changes by up to an order of magnitude. Further, incorporating additional solid solution endmembers changes the predicted stress-induced composition shifts of the other endmembers being considered. Finally, we demonstrate that Larché and Cahn’s approach yields positive entropy production, a requirement for any real process to occur. Our findings reveal that stresses between tens and a few hundred MPa can shift mineral compositions by several hundredths of a mole fraction. Consequently, mineral compositions could plausibly be used to infer stress states. We suggest that stress-composition effects could develop via intracrystalline diffusion in any high-grade metamorphic setting, but are most likely in hot, dry, and strong rocks such as lower crustal granulites.

The thermal and chemical structure of the middle atmosphere is determined by molecules of air absorbing high-energy, solar, ultraviolet radiation. The dominant photochemical reaction for forming the stratosphere is dissociation of a molecule of oxygen into two atoms of oxygen. When a molecule is dissociated, the two pieces fly apart at high velocity. Temperature of air is directly proportional to the average velocity of all its molecules and atoms squared. Thus, photochemical dissociation converts bond energy efficiently and completely into air temperature. A molecule of oxygen is dissociated by absorbing ultraviolet-C radiation with frequencies around 1237 terahertz, energies around 5.1 electronvolts. Since oxygen makes up 20.95% of Earth’s atmosphere, there is ample oxygen to absorb all solar ultraviolet-C of appropriate frequencies that reaches the stratosphere, keeping the stratopause 30 to 40 oC warmer than the tropopause. Thus, the stratosphere forms an “electric” blanket warming Earth—electric in the sense that the thermal energy comes from a distant source, Sun, not from the body under the blanket, Earth. The second most important photochemical reaction in the stratosphere is dissociation of ozone by ultraviolet-B radiation with frequencies around 967 terahertz, energies around 4.0 electronvolts. While ozone concentrations, even in the ozone layer, are less than 10 parts per million, ozone is continually being formed and dissociated in the endless ozone-oxygen cycle, absorbing most solar ultraviolet-B radiation. When atoms of chlorine reach the lower stratosphere especially in winter, ozone concentrations that normally increase in winter can be depleted. One atom of chlorine, under the right conditions, can destroy 100,000 molecules of ozone. Depletion of the ozone layer allows more ultraviolet-B radiation than normal to reach Earth. Ultraviolet-B radiation is observed to cause sunburn, cataracts, skin cancer and mutations. It also dissociates ground-level ozone pollution, warming air in populated regions and penetrates oceans more than one hundred meters, very efficiently increasing ocean heat content as observed. Because of the ozone-oxygen cycle, where there are increased concentrations of ozone in the atmosphere, there is increased temperature. Sudden stratospheric warmings of 30-40 oC within days are typically associated with high concentrations of ozone and occur most frequently at altitudes of 30-50 km where dissociation of oxygen and ozone are most efficient. In 1798, Sir Benjamin Thompson proposed the mechanical theory of heat generated by friction when boring canon. This mechanical theory evolved into two fundamental assumptions: 1) heat is a flux of thermal energy measured in watts per square meter and 2) the greater the amount of flux absorbed, the hotter the body will become. Note that this approach never addresses the issue of what heat or thermal energy are, physically. (Complete abstract in poster file.)

Novel fluid medium pressure cells were used to deform antigorite under constant stress creep conditions at low temperature, low strain rate (10^-9 - 10^-4 1/s), and high pressure (1 GPa) in a Griggs-type apparatus. Antigorite cores were deformed at constant temperatures between 75°C and 550°C, applying 8-12 stress-strain steps per temperature. The microstructures of deformed samples highlight the importance of basal shear and kinks to antigorite plasticity. Rheological data were fit with a low temperature plasticity law, consistent with a deformation mechanism involving large lattice resistance. When applied at geologic stresses and strain rates, the extrapolated viscosity agrees well with predictions based on subduction zone thermal models.

Drought Early Warning Systems (DEWSs) aim to spatially monitor and forecast risk of water shortage to inform early, risk-mitigating interventions. However, due to the scarcity of in-situ monitoring in groundwater-dependent arid zones, spatial drought exposure is inferred using maps of satellite-based indicators such as rainfall anomalies, soil moisture and vegetation indices. On the local scale, these coarse-resolution proxy indicators provide a poor inference of groundwater availability. The improving affordability and technical capability of modern sensors significantly increases the feasibility of taking direct groundwater level measurements in data-scarce, arid regions on a larger scale. Here, we assess the potential of in-situ monitoring to provide a localized index of hydrological drought in Somaliland. We find that calibrating a lumped groundwater model with a short time series of high-frequency groundwater level observations substantially improves the quantification of local water availability when compared to satellite-based indices over the same validation period. By varying the calibration length between 1-30 weeks, we find that data collection beyond 5 weeks adds little to model calibration at all three wells. This suggests that a short monitoring campaign is suitable to improve estimations of local water availability during drought, and provide superior performance compared to regional-scale satellite-based indicators. A short calibration period has practical advantages, as it allows for the relocation of sensors and rapid characterization of a large number of wells. A monitoring system with this contextualized, local information can support earlier financing and better targeting of early actions than regional DEWSs.

The investigation of the Ora Ignimbrite (~275 Ma) helps further our understanding of how vast amounts (>1,000 km3) of melt are generated, stored, and erupted from the shallow crust. As the last eruptive product of a slab rollback ignimbrite flareup that lasted for 10 Ma, Ora’s glacially incised outcrops tower over 1,300 m above Bolzano, Italy. Two key outcrops, early-erupted intracaldera vitrophyre and late-erupted outflow vitrophyre, provide well-preserved, glass-bearing juvenile material. Petrographic optical and electronic (back-scattered electron) analysis was used to document the textural features of minerals and glass. Glass and mineral major-element compositions were obtained using Energy-Dispersive X-ray (EDX) analysis on a Scanning Electron Microscope (SEM). Glass with low Na/high K concentrations and A/CNK ratios > 1.1 was deemed altered. Intracaldera vitrophyre contains two distinct fiamma types: very coarse-grained, crystal-rich (VCCR) and fine-grained (FG) fiamme. Glass in VCCR fiamme is homogeneous high-silica rhyolite (76.5-77.5 wt. % SiO2; normalized anhydrous) with low K2O values (3-3.5 wt. %). The FG fiamme have a broader SiO2 range (75-78 wt. % and 72-78 wt. %) and higher K2O values (3-4.5 wt. %). Outflow vitrophyre has medium-grained (MG) and fine-grained, crystal-poor (FGCP) fiamme. The MG fiamme have homogeneous high-silica rhyolite glass (76-78 wt. % SiO2) with lower K2O (2-3 wt. %). Glass in three FGCP fiamma form compositional continua from 68-78 wt. %, 67-79 wt. %, and 72-78 wt. % SiO2, and K2O varies substantially (0.5-3.5 wt. %). These results demonstrate mingling and mixing and suggest that multiple melt-rich zones contributed to the erupting magma. We propose that at least four separate magma bodies contributed to the Ora eruption. Each one evolved independently, leading to variable amounts of magma mingling and mixing. These results illuminate the subsurface architecture of a large silicic system during the final episodes of an ignimbrite flareup.

Basalt carbonation has gained traction as a key technology for avoiding the worst consequences of human-driven climate change. However, our understanding of this method’s promise is likely inflated by the specialized conditions used in many of the most well-known laboratory studies and demonstration projects. For technological, hydrogeologic, and energetic simplicity, many basalt CO2 storage projects will likely inject supercritical, not dissolved, CO2. Thus, fluids in these systems are likely to have low alkalinity and low pH, in contrast to many experimental and demonstration studies. Here, we present a series of geochemical models that explore the dependence of carbon mineralization efficiency on alkalinity and therefore pH at conditions relevant to these proposed operations. We modelled the interaction of basalt with CO2 enriched, seawater-derived aquifer fluid with varying initial alkalinities at 60°C using a custom thermodynamic database incorporating updated thermodynamic data for relevant primary and secondary minerals. The results reinforce the notion that alkalinity is an important driver for carbonate precipitation, ultimately because carbonate minerals are up to an order of magnitude more soluble at pH <5 than they are at pH >6. Alkalinity increases of 5 to 10% proportionally increase carbonate precipitation in the models. Our results thus demonstrate that the elevated alkalinity found in many of the most well-known basalt carbonation studies yield disproportionately high rates of carbon mineralization, which, in turn, frames basalt carbonation as an extremely rapid and exceptionally effective CO2 storage method. Although supercritical CO2 injection operations such as those we explore here are likely to achieve high fractions of CO2 mineralization over their lifetimes, this will likely take considerably longer and potentially be ultimately less effective, due to sluggish rates of CO2 dissolution and alkalinity generation.

Owing to the importance of serpentinites for planetary geochemical and geodynamic processes, there has been much work discerning the origins of their parent rocks, including distinguishing between serpentinites derived from a subducting plate vs. overlying mantle in exhumed subduction complexes. The island of New Caledonia (SW Pacific Ocean) provides a rare window into Cenozoic Pacific subduction processes. The island is unique in exposing both an exceptionally-preserved high-pressure, low-temperature subduction complex and one of the largest supra-subduction zone ophiolites in the world. Previous studies disagree on the origin of serpentinites in the subduction complex. In this study, we analyze twenty-three serpentinites from this subduction complex for whole-rock major and trace element geochemistry and stable isotope (δD, δ18O) compositions. Our data reveal two distinct groups of serpentinites: Group I samples in the northern portion of the complex are pervasively serpentinized, and exhibit enriched heavy rare earth element (REE) compositions and δ18O between +6.7‰ and +10.2‰. In contrast, Group II serpentinites in the south preserve relict orthopyroxene and olivine, and show depleted trace element compositions and comparatively lower δ18O values between +5.1‰ and +8.0‰. We interpret Group I serpentinites to derive from downgoing plate mantle, whereas Group II serpentinites derive from overlying mantle wedge, exhibiting remarkable similarity to the REE geochemistry of the structurally-overlying New Caledonia ophiolite. Our results establish the subduction complex in New Caledonia as an unusual natural record of the entrainment and exhumation of mantle from both the overlying mantle wedge and the downgoing plate in an oceanic subduction zone.

Forearc basin stratigraphy is expected to record a detailed history of the deformation and growth pattern of an accretionary wedge. However, the relationship between syntectonic basin sedimentation and growth of a wedge remains poorly understood, including (1) how deformation of the wedge modifies the basin stratigraphy and (2) how syntectonic sedimentation influences deformation of the wedge. In this study, we conducted scaled analogue sandbox experiments to reproduce accretionary wedges with and without syntectonic sedimentation. The results show that basin stratigraphy varied with the growth pattern of the accretionary wedge. In the case that wedge growth was dominated by trenchward accretion, the depositional area migrated landward. In contrast, prolonged underthrusting caused the sediment layers to be tilted landward and the depocenter to migrate landward. The occurrence of two types of basin stratigraphy (i.e., trenchward and landward migration of the depocenter) reflects a contrast in strength of the basal shear resistance between the inner and outer parts of the wedge due to sedimentation on the wedge. A change in the magnitude of normal stress acting on the wedge base likely influenced the mode of deformation of the wedge. A phase dominated by underthrusting can result in the combining a retro-wedge basin with a wedge-top basin, and yield a wide area of accommodation space in the forearc basin. These results suggest that forearc basin stratigraphy is influenced by the growth pattern of an accretionary wedge that is affected by syntectonic sedimentation.

Within a year of its launch date, the ATLAS altimeter on board ICESat-2 is already providing a wealth of critical data of interest across and beyond the cryospheric sciences. With the satellite returning nearly 1 TB of raw data per day, traditional practices of individual research groups downloading large granules of data and then subsetting, processing, and storing them locally are ultimately impractical. We are leading the development of icepyx (formerly icesat2py), an open source Python library designed to easily query, filter, download, and pre-process ICESat-2 datasets. The project’s documentation will include interactive Jupyter Notebook examples, providing a starting point for researchers to create and customize workflows to address their research questions. We actively invite contributions from the community to ensure the project develops in a way that meets a wide range of research needs. The project aims to leverage existing libraries that enable easy parallelization and can be run locally or on cloud-based platforms. As a result, researchers will ultimately download and store minimally-sized subsets of ICESat-2 data and have the opportunity to contribute their code to an established open science project. This presentation will serve to introduce icepyx to the cryosphere community and encourage early adoption of the library by researchers with all levels of coding experience.

A small gradient in the densities (Δρ) of two rivers was recently shown to develop coherent streamwise orientated vortices (SOVs) in the mixing interface of their confluence. We further investigate this phenomenon at the Coaticook and Massawippi confluence (Quebec, Canada) using eddy-resolved numerical modelling to examine how the magnitude and direction of Δρ; affect this secondary flow feature. Results show that a front from the denser channel always slides underneath the lighter channel independent of the direction of Δρ. When the fast tributary (Coaticook) is denser, coherent clockwise rotating density SOVs tend to form on the slow (Massawippi) side. However, when the slow Massawippi is denser by the same magnitude, anticlockwise secondary flow caused principally by shear induced interfacial instabilities develop on the fast Coaticook side. This shows the inertia of the tributary opposing the lateral propagation of the dense front shapes the secondary flow characteristics of the mixing interface. Moreover, in the absence of a density difference, anticlockwise SOVs are predicted by the model which correspond well to new aerial observations of anticlockwise SOVs at the site. A densimetric Froude number (Fd) convention accounting for the direction of Δρ is proposed to accurately convey the local inertial forces that oppose the lateral propagation of the dense front. Finally, a conceptual model of the mixing interface’s secondary flow structure over a spectrum of plausible Fd values is proposed. The Fd convention provides a flexible and consistent metric for use in future studies examining the effects of Δρ on river confluence hydrodynamics.

The Permian Basin has become the United States’ largest producer of oil over the past decade. Along with the rise in production, there has been an increase in the rate of low magnitude earthquakes, some of which have been associated with hydrocarbon extraction and wastewater injection. A detailed knowledge of changes to the subsurface can aid in understanding the causes of seismicity, and these changes can be inferred from InSAR surface deformation measurements. In this study, we show that both cm-level cumulative deformation, as well as mm-level coseismic deformation signals, are detectable in West Texas. In a region west of Mentone, TX, we reconstructed the subtle coseismic deformation signal on the order of ~5 mm associated with the recent M4.9 earthquake. Over ~100,000 km2 of the Permian Basin, we created annual cumulative LOS deformation maps, decomposing into vertical and eastward components where overlapping data are available. These maps contain numerous subsidence and uplift features near active production and disposal wells. The most important deformation signatures are linear streaks that extend tens of kilometers near Pecos, TX, where a cluster of increased seismic events was cataloged by TexNet. As validated by independent GPS data, our InSAR processing strategy achieved millimeter-level accuracy. A careful treatment of the InSAR tropospheric noise, which can be as large as 15 cm in West Texas, is required to detect surface deformation signals with such low signal-to-noise ratio. We developed an outlier removal technique based on robust statistics to detect the presence of strong, non-Gaussian noise. We compared the surface deformation solutions of multiple InSAR time series methods, and all of them produced more accurate and consistent deformation trends after removing outlier InSAR measurements. We are exploring a Bayesian generalization of SBAS velocity estimation by including probabilistic data rejection to determine which pixels should be excluded from the model fitting. This technique provides a full posterior distribution of the model parameters along with the best-fit surface velocity.

Apatite fission-track (AFT) tests of clastic samples from the Greater Khingan Mountains (GKM) in China show a center age of 260–62 Ma. Thermal modeling of observed fission-track-length distributions shows three stages of rapid cooling that may have been caused by extensions between 130 and 94 Ma, 30 and 15.3 Ma, and 45 and 0 Ma, and a heating event that may have been caused in part by changes in the subduction direction of the Pacific plate between 64 and 45 Ma. The cumulative exhumation since the Early Cretaceous, is approximately 3 km. The steady-state terrain model in the three-dimensional numerical simulation is highly consistent with the time and rate of the two-dimensional thermal history simulation for the Early Cretaceous exhumation event. The cooling age clusters of ~160 to 100 Ma are similar in the GKM and Hailar-Erlian Basins. This correlation provides a basin–mountain link for the two tectonic domains. Such a basin–mountain coupling lasted through 100–42 Ma, as supported again by the shared cooling ages of samples from the GKM and detritus from the range-bounded basins on the two sides of the mountain range. We interpreted the 130–94 Ma cooling event recorded in the GKM as a result of crustal thickening in response to the closure of the Mongolia-Okhotsk Ocean. An increase in the subduction velocity of the Pacific plate since ca. 45 Ma may have created a post-arc extensional tectonic setting that has prevailed to the present in the GKM.

Active faulting and Deep-seated Gravitational Slope Deformation (DGSD) constitute common geological hazards in mountain belts worldwide. In the Italian central Apennines, km-thick carbonate sedimentary sequences are cut by major active normal faults which shape the landscape generating intermontane basins. Geomorphological observations suggest that the DGSDs are commonly located in the fault footwalls. We selected five mountain slopes affected by DGSD and exposing the footwall of active seismic normal faults exhumed from 2 to 0.5 km depth. We combined field structural analysis of the slopes with microstructural investigation of the slipping zones from the slip surfaces of both DGSDs and major faults. The collected data show that DGSDs exploit pre-existing surfaces formed both at depth and near the ground surface by tectonic faulting and, locally, by gravitational collapse. At the microscale, the widespread compaction of micro-grains (e.g., clasts indentation) forming the cataclastic matrix of both normal faults and DGSDs is consistent with clast fragmentation, fluid-infiltration and congruent pressure-solution mechanisms active at low ambient temperatures and lithostatic pressures. These processes are more developed in the slipping zones of normal faults because of the larger displacement accommodated. We conclude that in carbonate rocks of the central Apennines, DGSDs commonly exploit pre-existing tectonic faults/fractures and, in addition, localize slip along newly formed fractures that accommodate deformation mechanisms similar to those associated to tectonic faulting. Furthermore, the exposure of sharp slip surfaces along mountain slopes in the central Apennines can result from both surface seismic rupturing and DGSD or by a combination of them.

Gas and vapour emissions from subglacial or subnivean volcanoes are capable of melting voids and passageways, here termed glaciovocanic caves and chimneys, in the overlying ice/snow. Glaciovolcanic caves (sub-horizontal) and chimneys (vertical) have been documented within a variety of volcanic regions around the world, with their formation sometimes preceding volcanic eruptions. Studying the formation and evolution of glaciovolcanic caves and chimneys and their relation to changes within the associated volcanic and glacial systems, therefore has potential to inform glaciovolcanic hazard assessments. In 2016, glaciovolcanic chimneys were discovered within Job Glacier in the Mt. Meager Volcancic Complex, British Columbia, Canada. The hypothesis that the chimneys formed as a result of glacier thinning, rather than due to an increase in volcanic activity, has yet to be tested. Here we seek to describe the morphology of these glaciovolcanic features, with respect to glaciological conditions and geothermal heat fluxes, using analytical models. By adapting existing analytical models of subglacial hydrological channels to account for the flow of geothermal gases instead of water, we derive the opening and closure rates for glaciovolcanic caves and chimneys. We use idealized glacier geometries and simplified descriptions of the energy transfer between the geothermal gases and the ice walls to facilitate our analysis. Steady-state geometries are found by balancing the melt opening, internal energy loss and the closure due to ice creep, and presented as functions of glacier thickness and geothermal heat flux. Our analytical results will be used to guide numerical simulations with more complex geometries and transient glaciovolcanic conditions. A better understanding of these complex interactions will facilitate more effective assessment of potential precursory signals of volcanic activity.