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The Tarim basin not only is one of the main targets for hydrocarbon exploration in China, but also hosts the Early Permian LIP, thereby providing an ideal laboratory to investigate how the LIP eruptions interact with the petroleum system in the volcanic-affected basins. Six major second-order domes were identified in the first-order dome that involves the entire Tarim LIP, based on seismic probing and lithofacies and stratigraphic observations in boreholes and the stratigraphic sections. These second-order domes are characterized by abundant Permian basaltic dykes and volcanic craters, indicative of the origin from the LIP eruption. They also are the sites of the almost all Paleozoic oil and gas reservoirs in the Tarim basin. Dating on authigenic illites collected from 20 Silurian bituminous and oil-saturated sandstone samples in the Tarim basin, along with literature data, indicates that hydrocarbon charge and emplacement in the Paleozoic reservoirs prevalently occurred during 300–255 Ma, approximately concurrent with the eruption of the Tarim LIP lavas (300–262 Ma). Therefore, we propose that the LIP eruption not only created the second-order domes that provided space for the oil and gas charge but also triggered the rapid release of hydrocarbon through the volcanic vents, thereby controlling the formation of Paleozoic oil and gas fields in the Tarim basin.

This study assesses the contribution of Landsat 7 ETM + and Landsat 8 OLI images to observe existing fractures and faults of at least 12 km in length around the lakes Nyos, Monoun and Oku whose are three major crater lakes in the Cameroon Volcanic Line (CVL) environment. The results obtained using principal component analysis, directional filters and linear densities show many similarities and some differences. In fact, Landsat 7 ETM+ and Landsat 8 OLI images present 427 lineaments in common, including all known geological linear structures, certain geophysical lineaments and some new fractures. This proves that the area is much more fractured than previously known and that only the environments of lakes Nyos and Monoun are crossed by faults and fractures. Apart from the similarities, the differences observed relate to the lineaments specific to each image, their main direction, their length and the values ​​of the fracturing densities. Also, the results show that the Landsat 7 ETM+ and Landsat 8 OLI images are suitable for the structural research in the CVL environment. But, the Landsat 8 OLI images are more efficient as they have made it possible to reconstitute almost all known geological structures and their lengths.

Gas-rich discharges of magma produced pyroclastic vents on the lunar surface. Calculations suggest those pyroclastic vents repeatedly generated 1012 to 1015 g of H2O and CO + CO2 for pyroclastic volumes of 10 to 500 km3 early in lunar history, particularly during the first billion years of lunar history. Some of those volatiles migrated to the lunar poles where they could be trapped in permanently shadowed regions (PSRs). The largest indigenous source of volatiles in the south polar region was volcanism that occurred on the floor of the Schrodinger impact basin. Here a large pyroclastic vent ceased erupting ∼ 3.70 +0.02-0.03 Ga, releasing H2O, CO-CO2, F, S, and Cl vapor species, including calculated values of 3.0 × 1013 to 1.6 × 1014 g H2O. A transport and depositional model suggests 1.1 × 1010 kg (12%) of that water may have been trapped in the south polar region.

The only martian rock samples on Earth are meteorites ejected from the surface of Mars by asteroid impacts. The locations and geological contexts of the launch sites are currently unknown. Determining the impact locations is essential to unravel the relations between the evolution of the martian interior and its surface. Here we adapt a Crater Detection Algorithm that compile a database of 90 million impact craters, allowing to determine the potential launch position of these meteorites through the observation of secondary crater fields. We show that Tooting and 09-000015 craters, both located in the Tharsis volcanic province, are the most likely source of the depleted shergottites ejected 1.1 million year ago. This implies that a major thermal anomaly deeply rooted in the mantle under Tharsis was active over most of the geological history of the planet, and has sampled a depleted mantle, that has retained until recently geochemical signatures of Mars’ early history., The ejection sites of the martian meteorites are still unknown. Here, the authors build a database of 90 million craters and show that Tharsis region is the most likely source of depleted shergottites ejected 1.1 Ma ago, thus confirming that some portions of the mantle were recently anomalously hot.

The area surrounding Jaboi volcano, Indonesia, has been planned for geothermal energy development with capacity of ~ 50 Mwe. Geophysical surveys can contribute to the understanding of the hydrogeology of the area because they can provide information without interferences, which could potentially react to the flow of hot water. In many cases, the occurrence of a hot spring is closely related to its local fault system, which permits the flow of thermal fluid to its surface. This research applied the very low-frequency electromagnetic (VLF–EM) method and then compared it with electrical resistivity data to map fractures, faults, and geological aspects in the Jaboi volcano manifestation area. In tropical areas such as Indonesia, the VLF–EM method has been applied widely in studying subsurface structures. However, it is rarely used in volcanic areas with high terrain conditions even though the mobility of VLF methods is simpler than the electrical resistivity method. At the west side of the volcano, the 2D models from both VLF–EM and electrical resistivity showed the conductive zone (log 0.5–1.5 Ωm) found as a response to the manifestation, which has a similar direction with a local fault known as the Ceuneuhot fault. At the east side, the 2D models from both methods showed a similar conductive zone at depths of 15–25 m, which is caused by the existence of bedrock (> log 2.5 Ωm). The bedrock at depths of 0–10 m inhibits the rise of fluid to the surface so that there is no geothermal manifestation in the other local fault known as the Leumomate fault. In addition, the 2D models from the two methods showed the contrast of some fracture zones as entry and exit points of fluid in the Jaboi volcano. In addition, analysis of Landsat 8 optical images also showed high-temperature values and low vegetation indices in several active craters as indicators of volcanic activity. Based on the processed data, it is concluded that VLF–EM can be used as a fast and accurate method to provide information about near-surface structures in a geothermal field, and it can be used safely to suggest a location for drilling programs or to give contributions to protect geothermal springs.

This report gives a brief description of field work on the Kuril Islands in summer 2021 carried out by staff of the Institute of Volcanology and Seismology of FEB RAS within the framework of the Institute research theme and projects of the Russian Science Foundation (RSF) and Russian Fund for Basic Research (RFBR). To study chemical erosion of volcanic islands and to estimate hydrothermal export of magmatic volatiles, hydrological and hydrochemical works were carried out on the rivers draining the slopes and thermal fields of the Baransky volcano and the Bogdan Khmelnitsky volcanic massif (Iturup Island). Detailed hydrochemical studies with water sampling at different depths and a bathymetric survey of Lake Kipyashchey located in the caldera of Golovnin volcano (Kunashir Island) were performed. We also proceeded with studying the CO2 diffusion flux through thermal fields and volcanic lakes. In the course of ongoing regime observations on Ebeko volcano (Paramushir Island), aerial and infrared imaging of its near-crater part was carried out. For the first time since the eruption began in 2016, a quadcopter survey of the lake located in the Srednii (middle) crater of the volcano was conducted. For further analytical studies a large number of water and gas samples were taken, and the collection of sediments was replenished.

About 14.5 months after the 2018 eruption and summit collapse of Kīlauea Volcano, Hawai'i, liquid water started accumulating in the deepened summit crater, forming a lake that attained 51 m depth before rapidly boiling off on December 20, 2020, when an eruption from the crater wall poured lava into the lake. Modeling the growth of the crater lake at Kīlauea summit is important for assessing the potential for explosive volcanism. Our current understanding of the past 2500 years of eruptive activity at Kīlauea suggests a slight dominance of explosive behavior over effusive. The deepened summit crater and presence of the crater lake in 2019 raised renewed concerns about explosive activity. Groundwater models using hydraulic-property data from a nearby drillhole successfully forecast the timing and rate of lake filling. Here we compare the groundwater-model predictions with observational data through the demise of the crater lake, examine the implications for local water-table configuration, consider the potential role of evaporation and recharge (neglected in previous models), and briefly discuss the energetics of the rapid boil-off. This post audit of groundwater-flow models of Kīlauea summit shows that simple models can sometimes be used effectively to simulate complex settings such as volcanoes.

The Salpeterkop volcano forms part of what has been referred to as the Upper Cretaceous Sutherland Suite of alkaline rocks, an igneous province composed of olivine melilitites, carbonatites, trachytes and ultramafic lamprophyres. Salpeterkop is a remnant of the summit tuff ring structure that surrounds a crater which is almost 1 km in diameter and is filled with epiclastic strata.Five pieces of silicified wood were collected from the crater filled sediments, sectioned and identified as a new species of Cupressinoxylon, C. widdringtonioides. This is the first example of the fossil genus in South Africa. Only one member of the Cupressaceae s.l. occurs in southern Africa today. From the wide and indistinct growth rings in the fossil wood it can be deduced that the local climate was warm and humid with little or no seasonality, in support of global records of a warm Late Cretaceous. The preservation of the crater further signifies the low level of erosion the region has experienced since its emplacement.

This study is concerned with the Raikoke volcanic massif, part land, part undersea, situated in the northern Central Kuriles. It consists of Raikoke volcano-island and the Quaternary undersea volcano 3.18. The eruption of June 2019 did considerable damage to the fauna and flora of Raikoke Island, changing its aspect one more time. A lake appeared in its crater. Raikoke volcano-island is composed of moderate potassium rocks of medium alkalinity belonging to the tholeiitic series from basalts to andesites, which are typical arc lavas. This occasion is the first to publish the compositions of six samples taken on the island. The undersea volcano 3.18 at a depth of ~800 m has its base coalescing with Raikoke volcano-island. The near-summit part at depths of 260–230 m has several peaks, while extrusions have been identified in the northeastern and southeastern parts of the base. Volcano 3.18 is composed of andesites and basaltic andesites. The basaltic andesites belong to lavas of the moderately potassium suite in the normal-alkaline series. Our surveys suggest that undersea volcano 3.18 was formed during a geomagnetic reversal. Its edifice was found to contain feeding conduits and peripheral magma chambers.

The major earthquakes often trigger unrest of surrounding volcanic magma chambers. In recent years, three major earthquakes occurred around the Changbaishan volcano, but it was unclear whether these earthquakes triggered the unrest of the magma chamber. Based on geodetic data, we analyzed the volcanic activity according to the Global Position System (GPS) and leveling sites time-series and re-estimated the location and volume change of magma chamber from 2002 to 2005. Meanwhile, we calculated the dilatational strain variations of the deep magma chamber resulting from coseismic deformations caused by the 1999 Mw7.0 and 2002 Mw7.3 Wangqing deep earthquakes and the 2011 Mw 9.0 Tohoku-oki earthquake. Our results show: (1) Changbaishan has experienced four stages of unrest since 1999, and the biggest unrest of the shallow magma chamber occurred from 2002 to 2005; (2) the parameters of the shallow magma chamber simulated by the Mogi and Point Compound Dislocation Model (pDCM) show that the magma chamber is located in the northern part of the crater, with a depth of approximately 7 km. The volume of the magma chamber increased by 25–28 × 106 m from 2002 to 2005; (3) the strain variation beneath the Changbaishan volcano corresponding to the 1999 Wangqing earthquake was small. The 2002 Wangqing earthquake produced an expansion strain of about 4.4 nano-strain on the magma chamber at a depth of 550 km, and probably promoted the unrest of the Changbaishan volcano. The 2011 Tohoku earthquake induced the expansion of the shallow magma chamber and compression of the deep magma chamber. Although this event promoted shallow magma unrest, it inhibited deep magma unrest. This may explain why the Changbaishan did not show obvious unrest after the 2011 Tohoku earthquake. Therefore, more attention should be paid to earthquakes that can promote deep magma unrest in the Changbaishan volcano.

A 3D shear wave velocity model of the subsurface of Popocatepetl volcano was obtained using ambient noise tomography, employing the principal cross-terms of the empirical Green’s function. Daily cross-correlation waveforms were computed from the data recorded by four seismic broadband stations in 2012. Dispersion curves were estimated from the stack of anti-causal and causal parts for the three ground motion components. In the period ranging between 0.5 and 7 s, the radial component provided the most well-defined group velocity dispersion curves for Rayleigh waves. Dispersion curves for long paths (> 9.5 km) suggested the presence of a layered structure with group velocity values ranging from 0.5 to 3.0 km/s. Dispersion curves for short paths (< 7 km) and close to the volcano showed values similar to those for long paths but with a velocity inversion occurring between 3- and 5-s periods. Despite the scarce ray-path coverage, a tomography inversion provided the means to image an S-wave velocity anomaly (2.5–3.0 km/s) in the northern part of the crater at depths not larger than 6 km. The volcano-tectonic seismicity during 2012–2013 was found to be concentrated in the southern segment of this anomaly, which seems to mark a boundary between a solidified body (possibly a product of ancient volcanic craters) and the softer material.

The waveforms and spectral content of the earthquakes that were recorded during the period of higher activity on Avachinsky Volcano in 2019 were studied to identify three commonly accepted types of volcanic earthquake (VE), viz., volcano-tectonic, hybrid, and long-period events, as well as a fourth type, a “special” VE type having certain special features in its waveforms. We have identified 15 plane-oriented clusters and determined characteristics of the seismogenic planes. An analysis of the seismic events that were recorded in the fall of 2019 on the Molodoi Konus of Avachinsky Volcano suggests that the resumption of activity was related to the magma bodies due to the 1991 eruption which exist in the cone body and to their interaction with atmospheric precipitation. The most likely cause of light flashes above the crater observed on December 8 seems to have been interaction between hydrogen-charged volcanic gas and air oxygen.

This study aims to gain a better understanding of the factors leading to the expressed shape of individual maars in volcanic fields. Maars are volcanic features produced by phreatomagmatic eruptions which excavate a crater beneath the pre eruptive surface through the explosive interaction of magma and water. Maar craters take on a wide range of shapes including, circular, elliptical, and polylobate. Across all maar fields, the existence of one or more axis of elongation is commonplace. Identification of the factors which lead to, and control, elongation in individual maars will help improve the accuracy of current hazard mapping and safety protocols. In order to determine whether the orientations of elongation are controlled by existing structures and regional stress, the primary and secondary directions of elongation of maar craters from a range of tectonic settings were measured. Maars were found to exhibit similar primary elongation orientations within each field. Influence of regional stress was identified in the geographic placement of maars along lineaments in most fields. Although many maars were found in lineaments identified through nearest neighbor analyses, they rarely share primary elongation orientations with the lineaments they compose. Furthermore, maars which shared similar primary elongation orientations with one another were not found to be grouped close together geographically. Overall, the number of maars in each field which share primary elongation orientations with existing structures (faults) and nearest neighbor lineaments does not suggest regional structural control over primary elongation orientation in any field. The tendency of maars to exhibit similar primary elongation orientations within a field, coupled with the lack of correlation with structural controls shows that the elongation orientations of maars are likely governed by more local controls related to host rock material, explosion induced changes to the stress regime, or hydrology.

The earth crust is made up of variety of minerals. These minerals are having very significant applications in our day today life. The various studies, characterizing physical, chemical, electrical, structural properties, have been carried out on the Lonar crater for studying mineralogy, surface morphology and geology but has not been done by remote sensing technology. So, the proposed work focused on exploring the mineralogy at the Lonar crater by using high resolution hyperspectral imageries. The spectral reflectance of minerals was characterized by using FieldSpec4 spectroradiometer. The minerals at Lonar crater were explored by performing preprocessing and spectral analysis. The techniques used in the work are Spectral Angle Mapper and Spectral Feature Fitting. The results of the work marked the presence of pigeonite and augite at Lonar crater which indicates that this crater is the result of extrusive volcanic activity. Also, the presence of augite underneath basaltic igneous rocks as the rock type of Lonar crater. The salinity of the Lonar lake is proved by the presence of mirabilite and salt. Thus, the important results of this work are presence of minerals quartz, actinol, jarosite, pigeonite, augite, albite, mirabilite and scolecite. The significance of these minerals related to the crater is discussed here. It also validated the existence of these minerals which were identified through the previous geological, chemical, physical, electrical and magnetic studies and the minerals pyrite, chlorite, richter, illite, limonite, allanite, amphibolite and margarite were also identified.

The geochemistry of volcanic gases has been fruitfully applied to identify important changes in the volcanic activity. This study reviews the dataset of the volcanic gas survey performed during 2009 and 2010 at Stromboli (Aeolian Islands - Italy). Dry gas collection occurred discontinuously at the crater fumaroles for subsequent chemical and isotopic (δ13C-CO2) analyses in the laboratory.A tailor-made device enabled continuous survey of H2 molar fraction and CO2 flux on the same site. Evaluation of the raw data was performed in accordance with air temperature, atmospheric pressure, wind speed and wind direction dataset. Both MLR (Multiple Linear Regression) and FFT (Fast Fourier Transform) analyses allowed filtering the dataset from the environmental effects. The MLR analysis indicated that wind speed and air temperature affected the CO2 flux. Changes in the atmospheric pressure promoted pumping effect of the fumarole gas and caused changes in the H2 molar fraction. The power spectral analysis revealed daily cycles in both gases. A digital signal filtering procedure enabled minimizing the environmental effects.This study confirmed that gas emissions from the crater fumaroles have both chemical ad isotopic composition similar to the magmatic gas phase. The results of the continuous survey showed that changes of both H2 and CO2 correlated with changes of the volcanic activity. Therefore, H2 and CO2 resulted effective tracers of the dynamics involving the plumbing system of Stromboli. Identification of changes in the gas emissions at open conduit volcanoes offers a great advance over the ground gas survey. The results of the continuous survey at Stromboli showed that H2 could apply as an auxiliary parameter of the CO2 flux in the surveillance programs of active volcanoes.

This study investigates anti-Chinese violence in the American West—focusing primarily on events in the Arizona Territory between 1880 and 1912—and the role of diplomatic relations between the United States and China in tempering the worst excesses of that violence. Recent scholarship asserts that the Chinese rarely suffered lynching and were commonly targeted for other types of violence, including coercion, harassment, and intimidation. Building on that work, this study advances a definition of racist violence that includes a broad spectrum of attacks, including the threat of violence. While affirming that such “subtler” violence achieved many of the same objectives as the “harsher” violence, it seeks to explain why whites used such radically different and less openly violent methods against this minority and explains why this difference mattered. Using these insights to interrogate the complex relationship between the United States and China, this essay shows that Chinese diplomatic influence stifled anti-Chinese mob violence by white Americans. It argues that this relationship denied white racists the same agency against the Chinese immigrants as they possessed against other racial and national minorities and thus forced them to “choose” the “subtler” acts of violence against this group rather than those usually employed against these others.

We present the results of geological and morphological analysis of LROC NAC images of a small volcanic crater Ina, D-shaped in plan view (2.9 × 1.9 km), and its immediate surroundings. This crater is located at the top of a very gently sloping shield volcano, the slopes of which, judging by the density of superimposed small craters, were formed ~3.5 Ga ago. Inside the crater there is a region with uneven relief and low hills, the density of small craters on which corresponds to an age of

This article assesses how the ground-penetrating radar RIMFAX will image the crater floor at the Mars 2020 landing site, where lithological compositions and stratigraphic relationships are under discussion prior to mission operation. A putative mafic unit (lava flow, volcanic ash, or volcaniclastic deposit) on the crater floor will be crucial in piecing together the chronology of deposition and for understanding the volcanic history in the region. In order to see how lithological properties and subsurface geometries affect radar sounding, a synthetic radargram is generated through forward modeling with a finite-difference time-domain method. The acquisition is simulated across the mafic unit as a succession of lava flows, exploring detection of internal structures and contacts to adjacent lithologies. To compare modeling results with the alternative formation scenarios, a discussion about sounding over a tephra or volcaniclastic material is presented. Similarities and differences between Martian and terrestrial lithologies can be related to electromagnetic properties relevant for radar sounding. This article, therefore, evaluates potential scientific insights gained from acquisition across the disputed mafic unit, in light of proposed hypotheses of lithological generation.

As the second common type of volcanic vent on Earth, maar-diatreme volcanoes and their post-eruptive lacustrine sediments are a main focus of volcanology, palaeolimnology, palaeoclimatology and palaeontology. A number of maar-type volcanoes have been found in Leizhou Peninsula, South China, but little is known about their eruption processes and detailed stratigraphy of the post-eruptive sediments. We present a combined geophysical and geological analysis to study the eruptive history and post-eruptive sediment stratigraphy of a large maar, the elliptical (1.8 × 3.0 km2) Jiudouyang (JDY) maar. The lacustrine stratigraphy revealed by drilling cores shows that the JDY maar lake has three major stages of evolution: (i) deep-lake sedimentary environment characterized by high autochthonous diatom productivity; (ii) shallow lake to swamp with very low water levels, characterized by a high total organic carbon (TOC) and abundant wood fragments; and, (iii) intermittent shallow lake and alluvial deposits composed of clay minerals and sand. The electrical resistivity tomography (ERT) values and lithological features are highly consistent, which clearly reveal the presence of ca. 50 m thick lacustrine sediments, directly underlain by a ca. 70 m thick basaltic lava rather than diatreme breccia in the crater. This infill sequence implies an alternation of eruption style from phreatomagmatic to Strombolian and/or lava flow, due to high magma flux and ascent rate of the Hainan Plume during the middle Pleistocene. The ERT data also reveal the initial phreatomagmatic crater floor at ca. 120 m depth. The initial crater had a large diameter/depth ratio (ca. 17), with an elongated shape (major axis to minor axis = 0.6), implying possible lateral vent migration during the eruption. A significant erosion under tropical weathering condition during the last few hundred thousand years, accounted for the large size of the maar crater. The study provides insights into the eruptive history and post-eruptive evolution of a large maar, as well as the spatial distribution of the lacustrine sediments.

The Pico do Fogo volcano, in the Cape Verde Archipelago off the western coasts of Africa, has been the most active volcano in the Macaronesia region in the Central Atlantic, with at least 27 eruptions during the last 500 years. Between eruptions fumarolic activity has been persisting in its summit crater, but limited information exists for the chemistry and output of these gas emissions. Here, we use the results acquired during a field survey in February 2019 to quantify the quiescent summit fumaroles' volatile output for the first time. By combining measurements of the fumarole compositions (using both a portable Multi-GAS and direct sampling of the hottest fumarole) and of the SO2 flux (using near-vent UV Camera recording), we quantify a daily output of 1060±340 tons CO2, 780±320 tons H2O, 6.2±2.4 tons H2S, 1.4±0.4 tons SO2 and 0.05±0.022 tons H2. We show that the fumarolic CO2 output from Pico do Fogo exceeds (i) the time-averaged CO2 release during 2015-type recurrent eruptions and (ii) is larger than current diffuse soil degassing of CO2 on Fogo Island. When compared to worldwide volcanoes in quiescent hydrothermal-stage, Pico do Fogo is found to rank among the strongest CO2 emitters. Its substantial CO2 discharge implies a continuous deep supply of magmatic gas from the volcano’s plumbing system (verified by the low but measurable SO2 flux), that becomes partially affected by water condensation and sulphur scrubbing in fumarolic conduits prior to gas exit. Variable removal of magmatic H2O and S accounts for both spatial chemical heterogeneities in the fumarolic field and its CO2- enriched mean composition, that we infer at 64.1±9.2 mol. % H2O, 35.6±9.1 mol. % CO 0.26±0.14 mol. % total Sulfur (S ), and 0.04±0.02 mol. % H2.

Lower Cretaceous volcanic rocks that contain major natural fractures are the main natural gas reservoirs in the deep Xujiaweizi depression of the northern Songliao Basin in China. Natural fractures are mainly tectonic fractures, in addition to some shrinkage, dissolution, and cryptoexplosive fractures. Analyzing various sources of data revealed that fractures are generally better developed in the rhyolites and trachytes of the crater and near-crater group. Also, tectonic fractures are developed to a higher degree in the hanging wall of faults, with the degree of development decreasing with increasing distance from the fault planes. More than 85% of these fractures are found to be unfilled and, when connected by pores, provide the main effective storage volume for these volcanic reservoirs (up to ∼75%). Natural gas production is closely related to the linear density (P10) of unfilled tectonic fractures and the angle between the orientation of unfilled tectonic fracture and the corresponding direction of the maximum horizontal stress component. The results show that natural gas production is elevated when the average P10 exceeds 2 m−1, and the average included angle is less than 30°. Finally, it was concluded that within the study area, unfilled tectonic fractures of near east-west strikes, which have smaller included angles (

Multidisciplinary petrologic, mineralogical, and geochemical studies have been carried out for the first time concerning near-crater tephra from the world-largest intraplate stratovolcano (Erebus). The volcano is characterized by a unique basanite–phonolite effusive lineage. We studied the grain-size and chemical compositions of the tephra and the concentration of trace elements in it, the mineral phase composition, lithogenic gases encapsulated in the tephra, an atomically dispersed carbonaceous substance, and the isotope composition of carbon in it. We came to the conclusion that the tephra studied here can be treated as an explosive analogue of anorthoclase lava phonolites that terminate the continuous series of magmatic differentiates known as the Erebus lineage.

The phreatomagmatic eruption at Aso volcano on October 8, 2016, released PDC and fallout up to 320 km from the vent, providing an opportunity to study the dispersal and sedimentation of tephra bearing wet and dry aggregates. We investigated fresh air-fall tephra and conducted both dry- and wet-sieving to assess the size distribution of both aggregate-bearing deposits on the ground and particles in the plume prior to aggregation. The tephra was asymmetrically distributed in the ENE direction, with a relatively wide distribution and small maximum grain sizes north of the depositional axis, reflecting different wind directions at each altitude. The secondary accumulation maxima at 4–8 km NE from the vent was characterized by the segregation of lapilli followed by accretionary pellets that were rapidly created by aggregation in the wet plume, thereby enhancing the removal of airborne ash. Coalesced aggregates possibly arose from salt precipitation processes. For dry aggregates fallen in medial-to-distal regions, observed deposition duration and fall velocity calculations concluded that fine ash was deposited not as individual particles but as aggregates. Most grain-size distributions along the dispersal axis based on the two sieving methods used were multimodal, with the coarser mode fining according to distance from the vent and the finer mode stabilizing at around 4ϕ; this is interpreted as resulting from the mixture of grain-size distributions with different origins, i.e., the normal settling of individual clasts and particle aggregation. The wet-sieved total grain-size distribution included 20.4 wt% fine ash compared with only 2.4 wt% fine ash in the dry-sieved distribution, suggesting that aggregated particles accounted for 18 wt% of the deposit. Total grain-size distributions based on wet-sieving showed extremely poor sorting that could be explained by the following causes: the release of coarse-grained ejecta originating from the host rock of the crater, fine particles due to fragmentation from a phreatomagmatic eruption, the supply of water and salt from the crater to the plume, and aggregation enhancement of the fine ash on the ground, reflecting the effect of the crater lake as external water source.

During the 2018 eruption of Kīlauea Volcano, Hawai'i, scientists relied heavily on a conceptual model of explosive eruptions triggered when lava-lake levels drop below the water table. Numerical modeling of multiphase groundwater flow and heat transport revealed that, contrary to expectations, liquid water inflow to the drained magma conduit would likely be delayed by months to years, owing to the inability of liquid water to transit a zone of very hot rock. The summit of Kīlauea subsequently experienced an ∼2-month period of consistent repeated collapses, and the crater now extends below the equilibrium position of the water table. Liquid water first emerged into the deepened crater in late July 2019. The timing of first appearance of liquid water (about 14 months postcollapse) and the rate of crater lake filling (currently ∼27 kg/s) were well-predicted by the numerical modeling done in late spring 2018, which forecast liquid inflow after 3 to 24 months at rates of 10 to 100 kg/s. A second-generation groundwater model, reflecting the current crater geometry, forecasts lake filling over the next several years. The successful 2018 to present forecasts with both models are based on unadjusted in situ permeability estimates (1 to 6 × 10-14 m2 ) and water-table elevations (600 to 800 m) from a nearby research drillhole and geophysical surveys. Important unknowns that affect the reliability of longer-term forecasts include the equilibrium water-table geometry, the rate of evaporation from the hot and growing crater lake (currently ∼29,000 m2 at 70-80 °C), and heterogenous permeability changes caused by the 2018 collapse.

Pyroclastic deposits of the Holocene Igwisi Hills kimberlite volcanoes, Tanzania, preserve unequivocal evidence for rapid, syn-eruptive agglutination. The unusual pyroclasts are composed of ash-sized particles agglutinated to each other by thin necks. The textures suggest the magma was disrupted into droplets during ascent. Collisions between particles occurred within a volcanic plume and on deposition within the conduit to form a weakly agglutinated, porous pyroclastic deposit. Theoretical considerations indicate that agglutination occurred over short timescales. Agglutinated clasts were entrained into weak volcanic plumes and deposited around the craters. Our results support the notion that agglutination can occur during kimberlite eruptions, and that some coherent, dense rocks in ancient kimberlite pipes interpreted as intrusive rocks could instead represent agglutinated pyroclastic rocks. Differentiating between agglutinated pyroclastic rocks and effusive or intrusive rocks in kimberlite pipes is important because of the potential effects that pyroclastic processes might have on diamond concentrations in deposits.

Cenozoic basalt, which is widespread in Mongolia, has been attracting the attention of Central Asian researchers since the beginning of the last century. This study identified the geomorphological shape of the Khorgo volcano. The main purpose of the study is to determine the origin and morphological form of Khorgo volcano, a key representative of Cenozoic volcanism. In general, there are several types of morphological forms associated with lava overflow, and it is important to determine which types are the most common and also to establish a link between them. Geomorphological studies in this area have not been conducted in Mongolia. Spatial improvement and morphometric methods satellite imagery had identified Khorgo volcanic faults.Khangai magmatism had thinned its crust to 45 km during the Tariat-Chuluut volcanic activity. It can be concluded that this was due to the thinning of the continental crust in the Khangai Mountains because of mantle plume. During this time, tectonic faults formed were formed, which had broken through the earth's crust. Part of this fault was formed in the vicinity of Khorgo Mountain from northwest to southeast, and lava flowed with the basic composition, which led to the formation of the current morphological form of Khorgo volcano. The lava flow was less than 45% silica and potassium-dominated, which blocked the Suman River valley and formed the present-day Terkhiin Tsagaan Lake. The morphometric analysis compared the morphology of a typical volcano, which showed that the mouth of the crater of the Khorgo volcano has a slope slanting about 45 degrees, it is about 100 meters in depth, with a diameter of about 500 meters. By comparing the basalt composition of the Khorgo volcano and its morphometric characteristics with other standard volcanoes, it has been determined that it is in the form of a lava dome.

We investigated the magmatic–hydrothermal system of Aso Volcano, Japan, using broadband magnetotelluric (MT) data. To establish the nature of the shallow crust, a previous resistivity model based on data from 100 measurement sites in and around Aso volcano was revised using data from 9 additional sites near Naka-dake crater, which is located in the central part of the volcano. The components of MT impedance and the tipper vector were used to obtain the resistivity structure by three-dimensional inversion. The resistivity structure shows a subvertical low-resistivity (

The atmospheric pollution associated with the volcano Copahue activity was evaluated by analyzing the concentration of 33 elements including heavy metals in lichens. Fruticose thalli were collected between 7 and 18 km from the volcano crater, comprising a geothermal zone. Analytical data and geographic parameters were evaluated by Principal Component Analysis. Enrichment Factors was also calculated from elemental concentrations in the lichens. The Principal Components Analysis grouped the observations corresponding to the lichen samples in relation to the volcano crater distance, the thermal areas and the direction of the prevailing winds. The less impacted area by volcanic products presented a lower concentration of toxic elements (S and Hg) and a higher concentration of biological elements (Ca, K, Mg and Mn) than the other areas. All studied sites showed S and Se enrichments, even in the most distant areas from the volcano crater. The S concentrations in lichen recorded in areas of volcanic activity were higher for the volcanic complexes: Copahue-Caviahue and Puyehue-Cordon-Caulle (2800-12000 µg/g) than those reported for the rest of the world (600-2800 µg/g).

Exhalation ore mineralization is developing in the crater part of the active Kudryavy volcano. Lithogeochemical sampling results have revealed that Re, Au, Ag, As, Bi, Cd, Cu, Ge, In, Mo, Pb, S, Sb, Se, Sn, Te, Tl, W, Zn, Rb, and Cs accumulate in solid fumarole formations. These elements are transported by high-temperature volcanic gases and are deposited in mineral phases in the near-surface horizons of fumarole fields under decreasing temperature conditions. The contents of rhenium and other metals in volcanic deposits of fumarole fields locally reach values characteristic of ore deposits. Zoning of lithogeochemical anomalies in ore element associations has been revealed, expressed by the series Re, Mo, W, Au, Cu, Ag, Zn, Cs, Ge → In → Bi, Cd, Pb, Sn, Tl → As, Sb, Se, Te, (Cu, Ag, Au) in the direction from the highest-temperature fumarole fields to less hot, reflecting their temperature zoning. It is demonstrated that lateral geochemical zoning is caused both by the ore element contents in fumarole gases, which depend on temperature, and by differences in the optimal temperature ranges in which various elements precipitate from gases. Signatures for similar exhalation mineral formation processes have been revealed that occurred in the recent geological past at the neighboring extinct Sredny volcano. This suggests the occurrence of similar processes within other volcanic systems of Iturup Island, which increases the prospects for detecting complex exhalation-related manifestations of rare, base, and noble metals.

We collected volcanic ash immediately following the eruption of Mt. Asama on August 7, 2019, observed the characteristics of ash particles, and analyzed the water-soluble components. The volcanic ash consisted mostly of altered fragments, and no clear evidence of essential materials was found. The volcanic ash contained large amounts of water-soluble components, Cl and SO4 at concentrations of 8,710 mg/kg and 49,100 mg/kg, respectively. These results indicate that this eruption was caused by the phreatic explosion and that part of the volcanic edifice of Mt. Asama was fractured and emitted.

The unique case of carbon dioxide accumulation in the bottom layer of the acidic lake formed in the Guadiana open pit (Herrerias mine, SW Spain) led to exceptionally high dissolved gas pressures (ca. 5.0 bar at depths of 50–70 m). This CO2 has formed by carbonate (calcite, dolomite) dissolution during decades of interaction of the acidic water with the rocks of the pit walls and associated mine tunnels. The elevated dissolved gas pressures were only comparable to those found in the volcanic crater lakes of Cameroon like Nyos and Monoun, which erupted in the 1980s and sadly triggered the loss of hundreds of human lives. This gas pressure was not far from the absolute (hydrostatic plus atmospheric) pressure limiting CO2 solubility at depth, thus making this pit lake potentially dangerous for the possibility of a hypothetical limnic eruption. Following detailed field and experimental studies aimed at deciphering the source and accumulation patterns of CO2 in the lake, a degassing project started in 2014, which followed an upscaling strategy with construction and installation of progressively bigger pipelines capable of extracting increasingly higher flow rates of CO2-charged water from the deep part of the lake. As of May 2019, the degassing systems have successfully extracted most of the CO2 originally present in the lake (i.e. ≈ 123,000 m3 CO2), which has been discharged to the atmosphere in a controlled and safe way. The fountains became progressively smaller and finally stopped, due to the decreased gas pressure at depth. The larger pipes will serve as a regulating system in the future. This paper describes the main findings encountered during the degassing project, some relevant technical issues observed during the last 5 years (2014–2019), and lessons learnt from the Guadiana pit lake experience.

The second phase of field work in 2020 on the Alaid Volcano, located on Atlasov Island in the north of the Kuril Island Arc, was carried out on October 2. There was no snow in the crater at the time, and this made it possible to study the deep part of the crater and take samples of rocks and snow. The measurements of the temperature of fumarole gases showed that for the tested fumaroles it varied in the range of 35° to 95° C. Rock samples were also taken from the Svechka Rock and at Cape Shtormovoy. It was found that there is currently no water in Yuryev Creek, located in the west-northwest part of Atlasov Island. The studies carried out have made it possible to obtain new unique information, which will undoubtedly be useful to various researchers of active volcanoes in the Kuril island arc.

The crater and proximal effects of the largest known young meteorite impact on Earth have eluded discovery for nearly a century. We present 4 lines of evidence that the 0.79-Ma impact crater of the Australasian tektites lies buried beneath lavas of a long-lived, 910-km3 volcanic field in Southern Laos: 1) Tektite geochemistry implies the presence of young, weathered basalts at the site at the time of the impact. 2) Geologic mapping and 40Ar-39Ar dates confirm that both pre- and postimpact basaltic lavas exist at the proposed impact site and that postimpact basalts wholly cover it. 3) A gravity anomaly there may also reflect the presence of a buried ∼17 × 13-km crater. 4) The nature of an outcrop of thick, crudely layered, bouldery sandstone and mudstone breccia 10-20 km from the center of the impact and fractured quartz grains within its boulder clasts support its being part of the proximal ejecta blanket. Ministry of Education (MOE) National Research Foundation (NRF) Published version This work was funded primarily by the Earth Observatory of Singapore, which receives most of its funding from the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence initiative. We acknowledge and appreciate the participation and generosity of the Department of Mineral Resources and Environment, Thailand, the Department of Geology and Mines, Lao PDR, and the Facility for Analysis, Characterisation, Testing, and Simulation at Nanyang Technological University.

Tampusu Mountain (± 1500 m above sea level) is located between two famous geological tourism areas in North Sulawesi, namely Lake Linow and Lake Tondano. The position of Mount Tampusu, as well as the presence of geothermal manifestations in the surrounding area is interesting to study its geological aspects both on the surface and below the surface. This study aims to determine the existence of surface geological structures based on line density, and also to determine the presence and direction of subsurface geological structures based on gravity anomaly data in Tampusu Volcanic area. The fault and fracture density method is used to map the surface geological structure, while the gravity method is used to obtain information about the geological structure of the Tampusu volcanic area between the crater of Lake Linow and the Lake Tondano caldera. The existence of a fault is known to be west of the Lake Tondano caldera which is an extension from east to southeast of the Linow Lake crater. There is a relationship between the distribution map of the bouguer anomaly value and the map of lineament density along the Lake Linow crater to Lake Tondano caldera.

DOI: 10.17014/ijog.6.3.279-289 Guntur Volcano was in a dormant state even though its seismicity had increased on April, 2013 and August, 2013. In this study, determination of hypocentre and seismic velocity structure was conducted using seismic data from 2010 to 2014 as recorded by a seismic station of the Centre for Volcanology and Geological Hazard Mitigation of Indonesia (CVGHM). Volcano-Tectonic (VT) earthquakes were identified and carefully picked for P-and S-wave arrival times. More than 600 events of VT earthquakes from 2010 - 2014 were located using maximum likelihood estimation algorithm. The initial 1-D seismic velocity was calculated using Velest method in order to get the initial velocity as the input for the tomographic inversion. The results show distribution of VT hypocentres were clustered in three regions, namely Guntur Volcano, Kamojang geothermal area, and Darajat geothermal area. At the Guntur Volcano region, the VT events were located mostly at the northern part of the crater with the depth of hypocentre ranges from 0 - 4 km. The distribution of the VT events made alignment from the southwest to the northeast with the depth of hypocentre mostly ranges from 0 - 2 km at Kamojang region. Meanwhile, at Darajat geothermal area, the VT events were located at the depth of 0 - 2 km and made alignment from the southeast to the northwest. The low velocity zone associated with hot material or fluids was located at the depth of 5 km beneath the Guntur Crater. The location of VT earthquakes at the depth of 0 - 4 km beneath Guntur Crater was coincided with the area with high Vp and Vs anomalies. The low velocity zones were also found at Kamojang Crater and Cipanas hotspring area. It was predicted that the low velocity zone at the Kamojang Crater was related to a high temperature of the vapour system, whereas the reservoir of water was preferred to be dominated at the Cipanas hotspring.

The Sokoria geothermal field is a typical volcano-hosted geothermal system with widely distributed thermal features including altered ground, fumaroles and bicarbonate-sulfate-chloride springs. The main resource is situated beneath the flanks of the Kelimutu Volcanic Complex on Flores Island, Indonesia. This complex is renowned for its three acidic crater lakes that change color from time to time. Recent exploration and drilling results at Sokoria indicate the existence of a medium to high enthalpy resource, in the range of 200-260 °C, with slightly acidic fluids (pH 4.2 – 5.7) that have been sampled during flow testing of three wells without any physical evidence of corrosion of the surface facilities or the wellhead. Stable isotope data from these waters lie on or near the world meteoric line implying that the resource fluids as well as those from the different thermal waters are of meteoric origin typical of many geothermal systems. Initial testing results show that the first 5 MWe in the area can be commissioned by the end of 2019. This field could be developed to generate up to 30 MWe.

Deriving eruption source parameters from geophysical data is critical for volcano hazard mitigation, yet remains a challenging task in most volcanoes worldwide. In this work, we explored the temporal relationship between geophysical signals and eruptive parameters measured during six explosive episodes from the New South-East Crater of Mt. Etna (Italy). The quadratic reduced seismic velocity and pressure were calculated to track the temporal variation of volcanic elastic radiation, and the lava fountain height was estimated by thermal camera image processing. The temporal relationships between these geophysical and eruptive time series were studied. In particular, the first considered lava fountain exhibited a “clockwise hysteresis” pattern: higher seismic amplitude with respect to the fountain height during the waxing phase as compared to the waning phase. We also calculated the regression parameters for both linear and power laws, linking seismo-acoustic and eruptive time series. For the linear regressions, we found fairly constant values of the scaling factors in five out of six eruptive episodes, which can be considered as a promising step to derive eruption source parameters from geophysical data in real-time. Regarding power law regressions, a clear relationship was observed between the exponents determined for the power law linking quadratic reduced velocity and lava fountain height, and the time interval duration from the previous eruption. These results suggest that the condition of the uppermost part of the plumbing system (e.g. viscosity of residing magma and conduit conditions) play a key role in the seismic energy generation during the eruptions.

We have utilized THEMIS, MOLA, CTX and HiRISE data sets to investigate the morphologic and topographic characteristics of the northeast flank of Apollinaris Mons, a region with evidence for significant erosion of volcanic deposits. Using ArcGIS software, we mapped the geology of the northeast flank and obtained age estimates using crater size-frequency distributions from crater counts. Of the eight mapped units, three (Apollinaris Mons upper, mid-, and lower flank units) represent volcanic flank materials in various states of preservation. The Late Noachian-Early Hesperian upper flank unit is massive and contains joint-like vertical structures along the scarp faces of two large plateaus whose upper surfaces likely represent the original surface or near-surface deposits of Apollinaris Mons. Downslope-facing plateau scarps have up to 500 m of relief. Positioned below this unit are the mid-flank and lower flank units, each representing eroded surfaces within Apollinaris Mons flank materials that have stabilization ages between the Late Hesperian to Early Amazonian. Mantling material in the region contains cavities and boxwork-like textures that resemble patterns in terrestrial eroded pyroclastic flow deposits. Dome-shaped mounds west of the mapping region have morphologic similarities to terrestrial fumarolic mounds or possibly inverted impact craters. Both the texture and features suggest widespread pyroclastic deposits adjacent to Apollinaris Mons. Using MOLA gridded topography, we estimate that ~308 km3 of materials have been eroded along the flanks of the volcano. Statistical and histogram data from the thickness values of eroded materials shows that up to ~300 m of material has been removed from the majority of flank surfaces. Assuming steady state erosion of flank surfaces, we estimate an area-normalized loss rate of ~0.859 nm/yr for northeast Apollinaris Mons. This erosion rate is within the long-term range for Mars (~0.01–10 nm/yr) as estimated from MER landing site geology by Golombek et al. [2006].

Long-term deformation of Kusatsu-Shirane and Asama volcanoes in central Japan were investigated using Global Navigation Satellite System (GNSS) measurements. Large postseismic deformation caused by the 2011 Tohoku earthquake—which obscures the long-term volcanic deformation—was effectively removed by approximating the postseismic and other recent tectonic deformation in terms of quadrature of the geographical eastings/northings. Subsequently, deformation source parameters were estimated by the Markov Chain Monte Carlo (MCMC) method and linear inversion, employing an analytical model that calculates the deformation from an arbitrary oriented prolate/oblate spheroid. The deformation source of Kusatsu-Shirane volcano was found to be a sill-like oblate spheroid located a few kilometers northwest of the Yugama crater at a depth of approximately 4 $$\text {km}$$ km , while that of Asama was also estimated to be a sill-like oblate spheroid beneath the western flank of the edifice at a depth of approximately 12 $$\text {km}$$ km , along with the previously reported shallow east–west striking dike at a depth of approximately 1 $$\text {km}$$ km . It was revealed that (1) volume changes of the Kusatsu-Shirane deformation source and the shallow deformation source of Asama were correlated with the volcanic activities of the corresponding volcanoes, and (2) the Asama deep source has been steadily losing volume, which may indicate that the volcano will experience fewer eruptions in the near future.

The Chaihe–Arxan volcanic field is situated in the Greater Khingan Range of northeastern China. The volcanic field consists of over 40 monogenetic cones. Yanshan is the youngest volcano in this area, with a reported age of 2 ky BP. The regions surrounding the volcano was subjected to a large fire in 2006, allowing researchers to determine the eruption history of the volcano. During a 2-week comprehensive field investigation, we found Yanshan volcano exhibits three types of eruption products: pyroclastic blanket, multi-crater scoria cone, and lava flow. The eruption process of this volcano has since concluded. Its eruption activity was initially ambiguous Strombolian eruption of the north crater, followed by sub-Plinian eruption of the east crater, and finally lava flow effusive events from the west crater. The Yanshan basalts are composed of trachybasalt and basalt. Geochemical analyses for major and trace elements suggest that the Yanshan basalts do not undergo significant crustal contamination but undergo olivine and pyroxene crystallization. Experimental melt calculations and the La/Yb versus Sm/Yb diagram indicate that the Yanshan basalts are derived from the melting of garnet peridotite. The Sm/Yb versus Na/Ti diagram illustrates that the initial melting depth beneath Yanshan is approximately 140 km, and the lithospheric thickness is approximately 70 km. These results support the existence of a high-temperature and fluid-rich plume at a depth of 10–12 km beneath the youngest volcanic chain where Yanshan is located, indicating the possibility of eruption of this volcano. Therefore, it is necessary to strengthen volcanic monitoring at Yanshan.

Volcano-hydrothermal systems are governed by complex interactions between fluid transport, and geochemical and mechanical processes. Evidence of this close interplay has been testified by distinct spatial and temporal correlations in geochemical and geophysical observations at Vulcano Island (Italy). To understand the interaction between fluid circulation and the geochemical and geophysical manifestations, we perform a parametric study to explore different scenarios by implementing a hydro-geophysical model based on the equations for heat and mass transfer in a porous medium and thermo-poroelastic theory. Numerical simulations allow us to define the controlling role of permeability distribution on the different modeled parameters as well as on the geophysical observables. Changes in the permeability within the highly fractured crater area could be responsible for the fluctuations in gas emission and temperature recorded during the crisis periods, which are accompanied by shallow volcano-seismicity in the absence of significant deformation and gravity variations. Despite the general medium permeability of the volcanic edifice, the presence of more highly permeable pathways, which allow the gas to rapidly escape, as testified by the presence of a well-developed fumarolic field, prevents the pressure buildup at shallow depths. Graphic abstract

Tsiolkovskiy is a ~200 km diameter crater presenting one of the few mare deposits of the lunar far side. In this work, we perform a geological study of the crater by means of morpho-stratigraphic and color-based spectral mappings, and a detailed crater counting age determination. The work aims at characterizing the surface morphology and compositional variation observed from orbital data including the Lunar Reconnaissance Orbiter Wide Angle Camera and Clementine UVVIS Warped Color Ratio mosaics, and attempts a reconstruction of the evolutionary history of the Tsiolkovskiy crater through both relative and absolute model age determinations. The results show a clear correlation between the geologic and spectral units and an asymmetric distribution of these units reflecting the oblique impact origin of the crater. Crater counts performed using the spectral units identified on the smooth crater floor returned distinct age ranges, suggesting the occurrence of at least three different igneous events, generating units characterized by particular compositions and/or degree of maturity. This work demonstrates the scientific value of Tsiolkovskiy crater for a better understanding of the volcanic evolution of the Moon and, in particular, of its far side.

Returning humans to the Moon presents an unprecedented opportunity to determine the origin of volatiles stored in the permanently shaded regions (PSRs), which trace the history of lunar volcanic activity, solar wind surface chemistry, and volatile delivery to the Earth and Moon through impacts of comets, asteroids, and micrometeoroids. So far, the source of the volatiles sampled by the Lunar Crater Observation and Sensing Satellite (LCROSS) plume (1, 2) has remained undetermined. We show here that the source could not be volcanic outgassing and the composition is best explained by cometary impacts. Ruling out a volcanic source means that volatiles in the top 1–3 meters of the Cabeus PSR regolith may be younger than the latest volcanic outgassing event (~ 1 billion years ago; Gya) (3).

Mare domes, small shield volcanoes typically

Magnetotellurics (MT) is an important geophysical method for exploring geothermal systems, with the Earth resistivity obtained from the MT method proving to be useful for the hydrothermal imaging changes of the system. In this research, we applied the MT method to map the geothermal system of the Seulawah Agam volcano in northern Sumatra, a site intended for the construction of a geothermal power plant with an estimated energy of 230 Mwe. Herein, 3D MT measurements were carried out, covering the entire area of the volcano and the various intersecting local faults from the Seulimeum segment in the NW–SE direction. Based on Occam 2D inversion, a conductive anomaly (&lt, 10 ohm·m) near the surface was identified in response to specific manifestation areas, including the Heutsz crater on the northern side and the Cempaga crater on the southern side. A further conductive anomaly was also found at a depth of 1 km, which was presumably due to a clay cap layer covering the fluid in the reservoir layer below the surface, where the manifestation areas are formed at various locations (where faults and fractures are found) owing to the fluid in the reservoir rising to the surface. The MT modeling also revealed that the reservoir layer in Seulawah Agam lies at a depth of 2 km with a higher resistivity of 40–150 ohm·m, which is the main target of geothermal energy exploration. At the same time, the heat source zone where magma is located was estimated to lie in two locations, namely, on the northern side centering on the Heutsz crater area and the southern side in the Cempaga crater area. A clear 3D structure obtained via Occam inversion was also used to visualize the hydrothermal flow in the Seulawah Agam volcano that originates from two heat source zones, where one structure that was consistent across all models is the conductive zone that reaches a depth of 5 km in the south in response to the regional faulting of the Seulimeum segment. Based on the MT research, we concluded that the volcano has the geothermal potential to be tapped into power plant energy in the future.

Post-eruptive destabilization of volcanic edifices by gravity driven debris flows or erosion can catastrophically impact the landscapes, economies and human societies surrounding active volcanoes. In this work, we propose cosmic-ray muon imaging (muography) as a tool for the remote monitoring of hydrogeomorphic responses to volcano landscape disturbances. We conducted the muographic monitoring of Sakurajima volcano, Kyushu, Japan and measured continuous post-eruptive activity with over 30 lahars per year. The sensitive surface area of the Multi-Wire-Proportional-Chamber-based Muography Observation System was upgraded to 7.67 m$$^2$$ 2 ; this made it possible for the density of tephra within the crater region to be measured in 40 days. We observed the muon flux decrease from 10 to 40% through the different regions of the crater from September 2019 to October 2020 due to the continuous deposition of tephra fallouts. In spite of the long-term mass increase, significant mass decreases were also observed after the onsets of rain-triggered lahars that induced the erosion of sedimented tephra. The first muographic observation of these post-eruptive phenomena demonstrate that this passive imaging technique has the potential to contribute to the assessment of indirect volcanic hazards.

The Huaynaputina volcano, southern Peru, was the site of the largest historical eruption (VEI 6) in the Andes in 1600 CE, which occurred during the historic transition between the Inca Empire and the Viceroyalty of Peru. This event had severe consequences in the Central Andes and a global climatic impact. Spanish chronicles reported that at least 15 villages or settlements existed around the volcano, of which seven of them were totally destroyed by the eruption. Multidisciplinary studies have allowed us to identify and analyze the characteristics of six settlements buried by the eruption. Tephra fallout and pyroclastic current deposits (PDCs) had different impacts according to the settlement distance from the crater, the location with respect to the emplacement of PDCs along valleys, the geomorphological characteristics of the site, and type of constructions. Thus, Calicanto, Cojraque, and San Juan de Dios, located beneath the main axis of tephra dispersal lobe due west and/or on valley edges, were buried under several meters of pyroclastic deposits, while the villages of Estagagache, Chimpapampa, and Moro Moro, located to the S and SE of the lobe, were partially mantled by tephra. The 1600 CE Huaynaputina eruption created an important geological and cultural heritage, which has scientific, educational, and touristic values. Geo-touristic attractions are proposed based on identification, characterization, and qualitative evaluation of four groups totaling 17 geosites: volcanic geosites, volcanic-cultural geomorphosites, and hot springs. Seven geological roads along with seven viewpoints are proposed, which allow to value the most relevant landscapes, deposits and geological structures., This paper stems from the research project entitled “Evaluation of the impacts of the Huaynaputina eruption from tephro-stratigraphic and palaeo-climatic studies and applications to evaluation and dissemination of risk knowledge in Moquegua”, funded by the contract No. 015-2017 FONDECYT. We appreciate the participation and support of FONDECYT-CONCYTEC, Laboratoire Magmas et Volcans (LMV) of the Université Clermont Auvergne (UCA), the Institute for Research and Development (IRD), the Laboratoire Géosciences Réunion of the Université de La Réunion, Université de Paris, and CEREMA. We also thank the Regional Government of Moquegua, the District Municipality of Quinistaquillas and the Provincial Municipality Mariscal Sánchez Cerro, for the logistical support provided during the field work. Besides, we acknowledge funding from the I-SITE CAP-2025 (French government) challenge 4 “Social and economic impacts from volcanic activity” and ClerVolc Laboratoire d'Excellence. This work was also supported by “BQR 2015” and “Direction des Relations Internationales” of Université de La Réunion and benefited from an important technical support of STRATAGEM974 geophysical company. This study contributes to the IdEx Université de Paris ANR-18-IDEX-0001.

Sulfur dioxide (SO2) degassing at Strombolian volcanoes is directly associated with magmatic activity, thus its monitoring can inform about the style and intensity of eruptions. The Stromboli volcano in southern Italy is used as a test case to demonstrate that the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Copernicus Sentinel-5 Precursor (Sentinel-5P) satellite has the suitable spatial resolution and sensitivity to carry out local-scale SO2 monitoring of relatively small-size, nearly point-wise volcanic sources, and distinguish periods of different activity intensity. The entire dataset consisting of TROPOMI Level 2 SO2 geophysical products from UV sensor data collected over Stromboli from 6 May 2018 to 31 May 2021 is processed with purposely adapted Python scripts. A methodological workflow is developed to encompass the extraction of total SO2 Vertical Column Density (VCD) at given coordinates (including conditional VCD for three different hypothetical peaks at 0–1, 7 and 15 km), as well as filtering by quality in compliance with the Sentinel-5P Validation Team’s recommendations. The comparison of total SO2 VCD time series for the main crater and across different averaging windows (3 × 3, 5 × 5 and 4 × 2) proves the correctness of the adopted spatial sampling criterion, and practical recommendations are proposed for further implementation in similar volcanic environments. An approach for detecting SO2 VCD peaks at the volcano is trialed, and the detections are compared with the level of SO2 flux measured at ground-based instrumentation. SO2 time series analysis is complemented with information provided by contextual Sentinel-2 multispectral (in the visible, near and short-wave infrared) and Suomi NPP VIIRS observations. The aim is to correctly interpret SO2 total VCD peaks when they either (i) coincide with medium to very high SO2 emissions as measured in situ and known from volcanological observatory bulletins, or (ii) occur outside periods of significant emissions despite signs of activity visible in Sentinel-2 data. Finally, SO2 VCD peaks in the time series are further investigated through daily time lapses during the paroxysms in July–August 2019, major explosions in August 2020 and a more recent period of activity in May 2021. Hourly wind records from ECMWF Reanalysis v5 (ERA5) data are used to identify local wind direction and SO2 plume drift during the time lapses. The proposed analysis approach is successful in showing the SO2 degassing associated with these events, and warning whenever the SO2 VCD at Stromboli may be overestimated due to clustering with the plume of the Mount Etna volcano.

Understanding the distribution of trace organic material in a rocky environment is a key to constraining the material requirements for sustaining microbial life. We used an ultraviolet laser-induced fluorescence (LIF) spectroscopy instrument to characterize the distribution of organic biosignatures in basalts collected from two Mars-analog environments. We correlated the fluorescence results with alteration-related sample properties. These samples exhibit a range of alteration conditions found in the volcanic environments of Hawai'i Volcanoes National Park, Hawai'i (HI), and Craters of the Moon National Monument, Idaho (ID), including fumarolic systems. LIF mapping of the sample surfaces and interiors showed a heterogeneous distribution of areas of highly fluorescent material (point[s]-of-interest [POIs])-with fluorescence characteristics indicative of organic material. Results suggest that POIs are associated with secondary alteration mineral deposits in the rock's vesicles, including zeolites and calcite. Scanning electron microscopy with electron-dispersive X-ray spectroscopy was used to characterize the mineralogy present at POIs and support the evidence of carbon-bearing material. Overall, samples collected proximate to active or relict meteoric fumaroles from Hawai'i were shown to contain evidence for organic deposits. This suggests that these minerals are measurable spectroscopic targets that may be used to inform sample-site selection for astrobiology research.