Volcanic Areas Research Articles

Wudalianchi volcanism and mantle dynamics in Northeast China: New insight from Pn and Sn tomography

We determine new tomographic models of Pn anisotropic velocity and Sn isotropic velocity in and around the Wudalianchi volcanic area by inverting high-quality Pn and Sn arrival times manually picked from waveforms recorded at the newly deployed high-dense WAVESArray portable seismic stations. Our high-resolution Pn and Sn velocity models reveal strong lateral heterogeneities in the uppermost mantle under the study region. The average Pn and Sn velocities in the uppermost mantle are 8.2 and 4.5 km/s, respectively. Both Pn and Sn velocity models exhibit obvious low-velocity (low-V) anomalies under the Wudalianchi and Keluo volcanoes, whereas under the Songliao basin distinct high-velocity (high-V) zones are revealed. In particular, our Pn model reveals two separate low-V anomalies under the Nuomihe and Halaha volcanic groups, suggesting that they have different deep origins. A large-scale L-shaped low-V zone exists under the Keluo, Wudalianchi, Erkeshan, and Xunke volcanoes, characterized by Pn-wave fast propagation directions (FPDs) parallel with the low-V zone, suggesting that these volcanoes may have the same deep origin. Furthermore, southeast-opened U-shaped Pn FPDs exist around the Wudalianchi volcano, whereas NE-SW FPDs appear under the Great Xing'an range, which are generally consistent with SKS splitting measurements. This feature may reflect lithosphere-asthenosphere coupling beneath the Wudalianchi volcano associated with horizontal flows in the big mantle wedge and compressional tectonics under the Great Xing'an range. These results shed new lights on the Wudalianchi volcanism and mantle dynamics beneath Northeast China.

ALICENET – an Italian network of automated lidar ceilometers for four-dimensional aerosol monitoring: infrastructure, data processing, and applications

Abstract. ​​​​​​​Vertically resolved information on aerosol particles represents a key aspect in many atmospheric studies, including aerosol–climate interactions and aerosol impacts on air quality and human health. This information is primarily derived by lidar active remote sensing, in particular with extensive networks currently in operation worldwide. In Italy, the Institute of Atmospheric Sciences and Climate (ISAC) of the National Research Council (CNR) established the ALICENET network of automated lidar ceilometers (ALCs) in 2015. Since then, ALICENET has grown as a cooperative effort of Italian institutions dealing with atmospheric science and monitoring, and it currently includes instruments run by regional environmental protection agencies, universities, research centres, and private companies. In the current configuration, the network makes use of both single-channel ALCs and dual-channel, polarisation-sensitive-system ALCs (referred to as PLCs). The systems operate in very different environments (urban, coastal, mountainous, and volcanic areas) from northern to southern Italy, thus allowing the continuous monitoring of the aerosol vertical distribution across the country. ALICENET also contributes to the EUMETNET programme E-PROFILE, filling an Italian observational gap compared to other EU member states, which generally run extended ALC networks through national meteorological services. In this work, we present the ALICENET infrastructure and the specifically developed data processing centralised at CNR-ISAC, converting raw instrumental data into quantitative, quality-controlled information on aerosol properties ranging from attenuated backscatter to aerosol mass and vertical stratifications. This setup allows us to get insights into the 4D aerosol field over Italy with applications from near-real-time monitoring to long-term analyses, examples of which are reported in this work. Specific comparisons of the ALICENET products to independent measurements obtained with different techniques, such as particulate matter (PM) concentrations from in situ samplers and aerosol optical depth (AOD) from sun photometers, are also included here, revealing the good performances of the ALICENET algorithms. Overall, ALICENET represents a valuable resource to extend the current aerosol observational capabilities in Italy and in the Mediterranean area, and it contributes to bridging the gap between atmospheric science and its application to specific sectors, among which are air quality, solar energy, and aviation safety.

4D imaging of the volcano feeding system beneath the urban area of the Campi Flegrei caldera

This paper describes an approach to analyze ground deformation data collected by InSAR (Interferometric Synthetic Aperture Radar) imaging the volcano feeding system (VFS) beneath a caldera. The approach is applied to the Campi Flegrei caldera in southern Italy, a densely populated area at high risk for volcanic eruption. The method is a 4D tomographic inversion that considers a combination of 3D pressure sources and dislocations (strike-slip, dip-slip and tensile) acting simultaneously. This is in contrast to traditional methods that assume a priori geometries and type for the volcanic source. Another novelty is that we carry out a time-series analysis of multifrequency InSAR displacement data. The analysis of these multiplatform and multifrequency InSAR data from 2011 to 2022 reveals an inflating source at a depth of 3–4 km that is interpreted as a pressurized magmatic intrusion. The source broadens and migrates laterally over time, with a possible new magmatic pulse arriving in 2018–2020. The model also identifies a shallow region (at 400 m depth) that may be feeding fumaroles in the area. The analysis also reveals a zone of weakness (dip-slip) that could influence the path of rising magma. This method provides a more detailed dynamic 4 - dimensional image of the VFS than previously possible and could be used to improve hazard assessments in active volcanic areas.

Analysis of radiative heat flux using ASTER thermal images: Climatological and volcanological factors on Java Island, Indonesia

This study focuses on analysing natural Radiative Heat Flux (RHF) anomalies to map out the heat distribution across the Java Island. Leveraging remote sensing techniques, we calculated natural RHF anomalies using Land Surface Temperature (LST) and Land Surface Emissivity (LSE) data obtained from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery. A key aspect of our approach was distinguishing between natural and anthropogenic heat sources by cross-referencing the LST Map with the Land Use Land Cover (LULC) map of Java Island. The study interprets natural RHF anomalies by examining regional trends in non-volcanic areas and local trends within volcanic regions, considering climatological and volcanological factors. Relation with climatological factors involves assessing soil moisture parameters from Soil Moisture Active Passive (SMAP) data, precipitation from monthly Global Precipitation Measurement (GPM) data, and classifications according to the Köppen-Geiger climate schema. Our regional analysis reveals high natural RHF anomalies in the northern regions of West Java, parts of Central Java, and most of East Java, attributed to low soil moisture and low precipitation in savanna and monsoon climates. On a more localised scale, RHF values are significantly high in volcanic areas, particularly around Central and East Java's volcanoes, such as Mt. Merapi, Mt. Slamet, Mt. Semeru, the Sidoarjo Mud Volcano, and Mt. Ijen. The Natural RHF anomalies at volcanoes in West Java were identified as not being high except at Mt Patuha. These areas exhibit average natural RHF anomalies ranging between 32.22 W/m2 and 115.13 W/m2, indicating strong and intense volcanic activity. The insights obtained from these findings explain the overall thermal characteristics of Java Island and highlight the presence of subsurface thermal zones associated with volcanic activity and geothermal potential.

On the Capabilities of the IREA-CNR Airborne SAR Infrastructure

In this work, the airborne Synthetic Aperture Radar (SAR) infrastructure developed at the Institute for Electromagnetic Sensing of the Environment (IREA) of the National Research Council of Italy (CNR) is described. This infrastructure allows IREA-CNR to plan and execute airborne SAR campaigns and to process the acquired data with a twofold aim. On one hand, the aim is to develop research activities; on the other hand, the aim is to support the emergency prevention and management activities of the Department of Civil Protection of the Italian Presidency of the Council of Ministers, for which IREA-CNR serves as National Centre of Competence. Such infrastructure consists of a flight segment and a ground segment that include a multi-frequency airborne SAR sensor based on the Frequency-Modulated Continuous Wave (FMCW) technology and operating in the X and L bands, an Information Technology (IT) platform for data storage and processing and an airborne SAR data processing chain. In this work, the technical aspects related to the flight and ground segments of the infrastructure are presented. Moreover, a discussion on the response times and characteristics of the final products that can be achieved with the infrastructure is provided with the aim of showing its capabilities to support the monitoring activities required in a possible emergency scenario. In particular, as a case study, the acquisition and subsequent interferometric processing of airborne SAR data relevant to the Stromboli volcanic area in the Sicily region, southern Italy, are presented

New bulk rock and age data on the changes in magma evolution during the Miocene, Galatean volcanic area, central Anatolia, Turkey: A review

The Galatean Volcanic Province (GVP) lies within the Sakarya tectonic belt in the northwest of central Anatolia, Turkey, south of the North Anatolian Fault, cropping out over 12,000 km2. It consists of Early Miocene intermediate to acid lavas, pyroclastic rocks, volcaniclastic deposits, and Late Miocene OIB-like basalts. Our study is based on new bulk geochemistry, SrNd isotopes, and 40Ar/39Ar dating of the volcanic rocks from the south-western part of GVP, but integrates all the available previous data to understand how magmas evolved in the post-collisional geodynamic condition in the GVP. The initial eruptions were rhyolitic, as domes or pyroclastic deposits (Group 1) and basaltic lavas (Group 2) during the Early Miocene. Group 2 is also represented by large volumes of basaltic-andesitic, trachyandesite-dacite/trachydacite lava flows, small intrusions, and pyroclastic deposits as generated between 21 and 14 Ma. Relatively low 87Sr/86Sr ratios (0.705–0.706) of the early rhyolites (Group 1), similar to all the rocks from Group (2), suggest the generation of hybrid melts with variable contributions of mantle-derived and crustal material. The volcanic activity ends with OIB-like basalts (11–7 Ma) showing the lowest 87Sr/86Sr (∼0.703) suggesting an asthenospheric origin.The geodynamic model, based on post-Cyprian slab rollback, results in long-term (22–13 Ma) post-collisional delamination/drip processes that support magmatism. This magmatism is generated in the lithospheric mantle, with the formation of basaltic melts and acid hybrid melts showing variable contributions of mantle-derived and crustal materials in a complex trans-crustal magma plumbing system. Complex mixing of various intra-crustal magmas and fractional crystallization processes generated a huge volume of volcanic rocks. The Late Miocene small-volume OIB basalts were asthenospheric melts that during the late stage recorded localized decompression melting processes.

The pre-Campi Flegrei caldera (>40 ka) explosive volcanic record in the Neapolitan Volcanic Area: New insights from a scientific drilling north of Naples, southern Italy

The oldest volcanism documented in near-vent sections around the Campi Flegrei (CF, southern Italy) caldera does not exceed ~78 ka, even though the mid- to ultra-distal tephrostratigraphic record would suggest that activity in this area started well before that. Reconstructing the activity preceding the large caldera-forming Campanian Ignimbrite (CI) eruption of ~40 ka, via surface geological surveys in proximal areas, is challenging because of the poor accessibility and paucity of sections recording the older chronostratigraphic interval. In order to fill the gap in knowledge of the activity preceding the CI eruption, a 113.2 m deep scientific drillhole was emplaced in the Ponti Rossi area, in the northern part of the city of Naples. The Ponti Rossi area was selected as representative of the stratigraphic setting prior to the CF caldera formation because it is close, although external, to any proposed caldera rim or downthrown area. The cored succession, consisting of pyroclastic deposits separated by paleosols, reworked humified deposits or subaerial erosional surfaces, has been logged and sampled for sedimentological, mineralogical, and geochronological analyses. Thirty-one Pyroclastic Units (PU) were identified. Based on the structural/textural features of the recovered sediments, the first relevant result is the possible absence of the CI, while the deposits of the ~15 ka Neapolitan Yellow Tuff eruption, the second largest caldera-forming event of CF, represent the shallowest sediments. 40Ar/39Ar age determinations on alkali feldspars, extracted from juvenile fragments collected at 45.8–45.9 (PU-29) and 99.5–99.6 (PU-1) metres of depth, yielded ages of 59.03 ± 0.50 ka and 110.00 ± 0.35 ka, respectively. The age obtained for the deepest cored unit, having sedimentological characteristics compatible with proximal deposition, represents the oldest age obtained for a pyroclastic deposit in the sequences near the CF caldera boundaries and extends by 30 ky the explosive history of this area. Furthermore, based on 40Ar/39Ar age constraints, at least 29 eruptions, spanning the ~59–110 ka interval, can be added to the volcanic history of the Neapolitan Volcanic Area. These eruptions can be largely attributed to the CF area, prior to the CI caldera formation, and testify to hitherto unknown, intense explosive activity.

Using iron speciation to track hydrocarbon migration in bleached rocks and its implications for reservoir reconstruction

Bleaching of red rock beds by hydrocarbons can provide valuable insights for hydrocarbon migration and reservoir transformation. This study investigated the bleaching effects of hydrocarbons on various rock types in the Dushanzi mud volcanic area. Bedrock and bleached samples of different lithologies, including mudstone, sandy mudstone and sandstone, were systematically collected and analyzed for their iron species, mineralogical and chemical compositions using Mössbauer spectroscopy, X-ray diffraction and X-ray fluorescence, respectively. The results indicate that the iron species of the studied samples were dominated by para-Fe3+ (from 44% to 76%), with variable contents of mag-Fe3+, para-Fe2+ and pyr-Fe2+. When compared to the related unbleached rocks, the bleached rocks exhibited a higher proportion of reduced Fe (para-Fe2+ and pyr-Fe2+). The pyr-Fe2+ in the sandstones and sandy mudstones was significantly higher than that of the mudstone interlayers. The observed variations in iron species were consistent with changes in mineralogical and chemical compositions, which can be correlated with the petrological properties of rocks. The increase of quartz and decrease of feldspar and carbonates in the bleached rocks could be attributed to the dissolution of feldspar and the subsequent secondary enlargement of quartz. Geofluids containing crude oils and natural gases preferentially dissolved K-feldspar over albite. The bleached rocks had a significant decrease in the proportion of kaolinite and a slight decrease in the proportion of chlorite, while the proportions of smectite and illite were increased. The dissolution of K-feldspar could provide sufficient K+ for the formation of illite, and the appearance of smectite in the bleached samples might be related to the dissolution of albite in an alkaline environment. The dissolution of carbonates and feldspar, along with the transformation of clay minerals, had a notable positive effect on the formation of secondary porosity, facilitating hydrocarbon migration. These findings provide valuable insights into the interactions between hydrocarbons and different lithologies, informing the impact of hydrocarbon migration on reservoir reconstruction in similar geological settings.

Respiratory and physical health consequences in older adults in a high-risk volcanic area: Comparison of two rural villages

Introduction Volcanism is an important natural producer of pollution that impacts health and the quality of the environment. Lung changes caused by exposure to volcanoes have been previously studied. However, limited information exists regarding the effects of prolonged exposure to volcanic compounds. So, this study aimed to analyze the pulmonary effects and stress tolerance in older adults for chronic exposure to the volcanic ashes of the Galeras volcano. Methods A descriptive cross-sectional study of association included rural inhabitants aged over 60 years from Genoy, a village located in a high volcanic hazard zone of Galeras volcano, 2603 meters above sea level. Those in this group, called exposed, were contrasted with a sample of El Encano inhabitants with similar socioeconomic and cultural characteristics. Both villages belong to the rural area of San Juan de Pasto in Colombia. Results It was found that of 31 exposed participants, 18 had obstructive alteration, and in the control group, it was found that of 31 subjects, 6 presented this alteration. The difference between the two groups was significant (p<0.001). A similar situation occurred with distal airway obstruction assessed with the forced expiratory flow of 25–75%. No significant differences were found in restrictive alteration between the exposed and unexposed groups. Conclusion Chronic exposure to volcanic compounds has generated obstructive changes in the population, and these changes were greater in number and severity than those in the control group of unexposed people.

Twenty Years of Thermal Infrared Observations (2004–2024) at Campi Flegrei Caldera (Italy) by the Permanent Surveillance Ground Network of INGV-Osservatorio Vesuviano

Thermal infrared (TIR) time series images acquired by ground, proximal TIR stations provide valuable data to study evolution of surface temperature fields of diffuse degassing volcanic areas. This paper presents data processing results related to TIR images acquired since 2004 by six ground stations in the permanent thermal infrared surveillance network at Campi Flegrei (TIRNet) set up by INGV-Osservatorio Vesuviano. These results are reported as surface temperature and heat flux time series. The processing methodologies, also discussed in this paper, allow for presentation of the raw TIR image data in a more comprehensible form, suitable for comparisons with other geophysical parameters. A preliminary comparison between different trends in the surface temperature and heat flux values recorded by the TIRNet stations provides evidence of peculiar changes corresponding to periods of intense seismicity at the Campi Flegrei caldera. During periods characterized by modest seismicity, no remarkable evidence of common temperature variations was recorded by the different TIRNet stations. Conversely, almost all the TIRNet stations exhibited common temperature variations, even on a small scale, during periods of significant seismic activity. The comparison between the seismicity and the variations in the surface temperature and heat flux trends suggests an increase in efficiency of heat transfer between the magmatic system and the surface when an increase in seismic activity was registered. This evidence recommends a deeper, multidisciplinary study of this correlation to improve understanding of the volcanic processes affecting the Campi Flegrei caldera.

Reduction in Olfactory Discomfort in Inhabited Premises from Areas with Mofettas through Cellulosic Derivative-Polypropylene Hollow Fiber Composite Membranes.

Hydrogen sulfide is present in active or extinct volcanic areas (mofettas). The habitable premises in these areas are affected by the presence of hydrogen sulfide, which, even in low concentrations, gives off a bad to unbearable smell. If the living spaces considered are closed enclosures, then a system can be designed to reduce the concentration of hydrogen sulfide. This paper presents a membrane-based way to reduce the hydrogen sulfide concentration to acceptable limits using a cellulosic derivative-propylene hollow fiber-based composite membrane module. The cellulosic derivatives considered were: carboxymethyl-cellulose (NaCMC), P1; cellulose acetate (CA), P2; methyl 2-hydroxyethyl-cellulose (MHEC), P3; and hydroxyethyl-cellulose (HEC), P4. In the permeation module, hydrogen sulfide is captured with a solution of cadmium that forms cadmium sulfide, usable as a luminescent substance. The composite membranes were characterized by SEM, EDAX, FTIR, FTIR 2D maps, thermal analysis (TG and DSC), and from the perspective of hydrogen sulfide air removal performance. To determine the process performances, the variables were as follows: the nature of the cellulosic derivative-polypropylene hollow fiber composite membrane, the concentration of hydrogen sulfide in the polluted air, the flow rate of polluted air, and the pH of the cadmium nitrate solution. The pertraction efficiency was highest for the sodium carboxymethyl-cellulose (NaCMC)-polypropylene hollow fiber membrane, with a hydrogen sulfide concentration in the polluted air of 20 ppm, a polluted air flow rate (QH2S) of 50 L/min, and a pH of 2 and 4. The hydrogen sulfide flux rates, for membrane P1, fall between 0.25 × 10-7 mol·m2·s-1 for the values of QH2S = 150 L/min, CH2S = 20 ppm, and pH = 2 and 0.67 × 10-7 mol·m-2·s-1 for the values of QH2S = 50 L/min, CH2S = 60 ppm, and pH = 2. The paper proposes a simple air purification system containing hydrogen sulfide, using a module with composite cellulosic derivative-polypropylene hollow fiber membranes.

Unveiling spatial variations in atmospheric CO2 sources: a case study of metropolitan area of Naples, Italy

In the lower atmosphere, CO2 emissions impact human health and ecosystems, making data at this level essential for addressing carbon-cycle and public-health questions. The atmospheric concentration of CO2 is crucial in urban areas due to its connection with air quality, pollution, and climate change, becoming a pivotal parameter for environmental management and public safety. In volcanic zones, geogenic CO2 profoundly affects the environment, although hydrocarbon combustion is the primary driver of increased atmospheric CO2 and global warming. Distinguishing geogenic from anthropogenic emissions is challenging, especially through air CO2 concentration measurements alone. This study presents survey results on the stable isotope composition of carbon and oxygen in CO2 and airborne CO2 concentration in Naples’ urban area, including the Campi Flegrei caldera, a widespread hydrothermal/volcanic zone in the metropolitan area. Over the past 50 years, two major volcanic unrests (1969–72 and 1982–84) were monitored using seismic, deformation, and geochemical data. Since 2005, this area has experienced ongoing unrest, involving the pressurization of the underlying hydrothermal system as a causal factor of the current uplift in the Pozzuoli area and the increased CO2 emissions in the atmosphere. To better understand CO2 emission dynamics and to quantify its volcanic origin a mobile laboratory was used. Results show that CO2 levels in Naples’ urban area exceed background atmospheric levels, indicating an anthropogenic origin from fossil fuel combustion. Conversely, in Pozzuoli's urban area, the stable isotope composition reveals a volcanic origin of the airborne CO2. This study emphasizes the importance of monitoring stable isotopes of atmospheric CO2, especially in volcanic areas, contributing valuable insights for environmental and public health management.

Vertical gravity gradient in volcano monitoring – In situ measured or theoretical? (Campi Flegrei study)

We analyse the vertical gravity gradient (VGG) properties at calderas using the Campi Flegrei (CF) site in Italy. In situ observed VGG values can depart significantly from the theoretical (normal) value of −308.6 μGal/m, particularly in areas of rugged relief. It is assumed that in sufficiently flat areas, the effect of geology, i.e., of the subsurface density heterogeneities, on VGG could prevail over the effect of terrain (topography), which can subsequently be neglected. With respect to the CF caldera, which is often considered as ‘reasonably flat area’, according to our findings the effect of topography on VGG is usually underestimated, while the effect of deeper geology is overestimated. We model the effect of the near topography on VGG at CF and subsequently verify the results of modelling by in situ observations to support our predictions. The results show that, in terms of VGG, the topographic relief plays a more significant role than the assumed geological sources even at ‘flat’ calderas such as CF. For a better understanding, in addition to CF, we analyse the effect of deeper geological sources on VGG also in the territory of Slovakia using a detailed gravimetric database of Slovakia. As a result, we question the use of in situ observed VGG values when processing and interpreting observed time-lapse gravity changes in volcanic areas accompanied by surface deformation.

Geochemical and isotopic features of the Early Cretaceous volcanism of the Torey Volcanic Field (Eastern Transbaikalia, Russia) as a record of the transition from pyroxenite to eclogite mantle source

The Mesozoic magmatic activation in Central and Northeast Asia resulted in the formation of a large volume of volcanic rocks with diverse compositions. The most dramatic compositional change occurred at the end of the Early Cretaceous, when mainly alkaline basaltic lavas began to erupt after subalkaline differentiated lavas. The nature of crustal and mantle processes that led to this change in volcanism remains unclear. The Torey Volcanic Field (TVF) of Eastern Transbaikalia (Russia) demonstrates a similar compositional change. Therefore, the TVF is crucial to studying the cause of the difference in geochemical and isotopic signatures of the Mesozoic volcanism in Central and Northeast Asia.TVF belongs to the northeastern end of the Eastern Mongolia Volcanic Area (EMVA). Like other volcanic fields of the EMVA, TVF formed in two stages: early (∼121–129 Ma) and late (∼101–119 Ma). The TVF is composed of subalkaline and alkaline basaltic trachyandesites – trachyandesites. All TVF rocks are characterized by negative Ti and Sr anomalies and positive Ba and Pb anomalies. Compared to the late TVF rocks, the early TVF rocks have distinct negative Ta and Nb anomalies and are highly enriched in light rare earth elements relative to heavy rare earth elements. TVF rocks have the following isotopic characteristics: 87Sr/86Sr(t) = 0.70477–0.70540, εNd(t) = − 0.9 – +2.4, 206Pb/204Pb(t) = 17.9–18.4, and 207Pb/204Pb(t) = 15.5–15.6. However, older rocks mainly have higher εNd(t) values and 206Pb/204Pb(t) and 207Pb/204Pb(t) ratios.Geochemical and isotopic data of samples suggest that the TVF formed by melting in the continental metasomatized lithospheric mantle (CMLM). Phlogopite-amphibole-rutile-bearing pyroxenite veins played a major role in the formation of older rocks. Eclogite, represented by the recycled oceanic crust or the buried lower continental crust, was dominant in the source of younger rocks. The common source for both groups of the TVF rocks was metasomatized hydrous peridotite.Lithospheric extension and subsequent asthenospheric upwelling led to melting in the CMLM and the formation of the TVF. At the early stage of the volcanism, melting occurred at relatively low temperatures where amphibole, phlogopite, and rutile were stable. Due to ongoing lithosphere extension, the melting of eclogite occurred at a higher temperature and/or lower pressure at the late stage of the volcanism.

Morphometric analysis of monogenetic volcanoes in the Garrotxa Volcanic Field, Iberian Peninsula

The Garrotxa Volcanic Field is situated in the northeast region of the Iberian Peninsula. It represents the most recent volcanic area within the Catalan Volcanic Zone, which is one of the volcanic provinces of the European Rift System, featuring over 50 dispersed eruptive vents.This study presents a comprehensive morphometric analysis of volcanic edifices, aiming to enhance our understanding of both volcanostratigraphy and the geomorphology of landforms within the Garrotxa Volcanic Field. Our methodology involved extensive fieldwork and detailed analysis of Digital Elevation Models (DEMs) to precisely determine the spatial distribution and morphometric parameters of the best-preserved volcanic structures in the area. The Garrotxa Volcanic Field exhibits an uneven spatial distribution of various volcanic landforms, with approximately 50 % comprising magmatic cones, primarily formed through Strombolian eruptions. The remaining 50 % is evenly divided between magmatic-phreatomagmatic volcanoes and phreatomagmatic tuff rings-maars. The morphometric characteristics of the three genetic types overlap significantly, showing no clear differences, although a few distinctions can sometimes be identified.The Garrotxa Volcanic Field displays a variety of eruption styles: 46 % of the identified eruptive sequences begin with phreatomagmatic activity, while 54 % start with predominantly magmatic explosive activity. Most eruptions show a transition through different phases.Data also indicate that the morphometric variability at the Garrotxa Volcanic Field stems from differences in the properties of pyroclastic sequences, resulting from their diverse eruption styles, as well as pre- and post-eruptive factors. Consequently, the results of the morphometric analysis are deemed insufficient for establishing a reliable chronology for the Garrotxa Volcanic Field.

Helium and carbon isotope compositions of thermal fluids in the northeastern Anatolia: Implications for the heat source and volatile flux

In this study, we make a quantitative assessment on the volatile flux of mantle-derived fluids and source of volatiles to explain the geologic controls on the transport of volatiles within thermal fluids of northeastern Anatolia. In line with this objective, we collected 22 samples (gas and water phase) from 16 geothermal fields in NE Turkey covering an area of nearly 100,000 km2 that extends from the eastern termination of North Anatolian Fault towards the Georgian and Armenian borders. The 3He/4He ratios of the samples (R) normalized to the atmospheric 3He/4He ratio (Ra = 1.4 × 10−6) vary from 0.31 to 7.15, and are considerably higher than the crustal value of 0.02Ra. Regarding spatial distribution of helium isotope composition, samples collected from areas of tectonic unrest around the Erzincan and Erzurum pull-apart basins in the southern part are represented by a higher range of 3He/4He ratios (>5 Ra) than those in volcanic areas to the east and northeast of the region. δ13CCO2 values of the gas samples varying from −20.76 to 5.43 ‰ are about 4–5 ‰ lower than δ13CDIC values of the water samples that range from −16.90 to 8.85 ‰, indicating CO2 removal from waters by degassing. CO2/3He ratios of gas samples falling in the range of 3.81 × 109 to 2.83 × 1012 imply that carbon is derived from the mixing between the crustal lithologies and mantle, the latter having a contribution up to 40 %. The maximum flux of mantle-derived fluids is found 88 mm/a at Erzincan (eastern part of the North Anatolian Fault Zone). This value is higher by a factor of about 10 than the western part of the fault zone. Calculations show that degassing from magmatic bodies is the sole mechanism to explain the high helium isotope compositions in the region. Therefore, we suggest that mantle-derived He contents might be due to extensive melting associated with active tectonism. The 3He/Heat ratios of thermal waters in northeastern Turkey were calculated in range of 0.25 to 29.7 × 10−15 cm3(STP)/J, consistent with the data reported for waters along the North Anatolian Fault, indicating a crustal heat source for the geothermal systems in northeastern Turkey.

The Volcanic Rocks and Hydrocarbon Accumulation in the Offshore Indus Basin, Pakistan

To analyze the impact of volcanic rocks in the Offshore Indus Basin on hydrocarbon reservoir formation, seismic data interpretation, seismic data inversion, and sea–land correlation analysis were carried out. The results show that, longitudinally, volcanic rocks are mainly distributed at the top of the Cretaceous system or at the bottom of the Paleocene, and carbonate rock platforms or reefs of the Paleocene–Eocene are usually developed on them. On the plane, volcanic rocks are mainly distributed on the Saurashtra High in the southeastern part of the basin. In terms of thickness, the volcanic rocks revealed by drilling in Karachi nearshore are about 70 m thick. We conducted sparse spike inversion for acoustic impedance in the volcanic rock area. The results show that the thickness of the Deccan volcanic rocks in the study area is between 250 and 750 m which is thinning from southeast to northwest. Based on sea–land comparison and comprehensive research, the distribution of volcanic rocks in the Indian Fan Offshore Basin played a constructive role in the Mesozoic oil and gas accumulation in the Indus offshore. Therefore, in the Indian Fan Offshore Basin, attention should be paid to finding Mesozoic self-generated and self-stored hydrocarbon reservoirs and Cenozoic lower-generated and upper-stored hydrocarbon reservoirs.

An updated reconstruction of Campi Flegrei caldera (southern Italy) ground deformation history and its interaction with the human sphere since Roman time

Since the 19th century, many scientists have tried to reconstruct the ground motions that occurred in the Campi Flegrei caldera, one of the most dangerous volcanos in the Mediterranean area. This study aims to assess the joint effects of vertical ground movements and anthropic forcing along the coasts of this volcanic area. A huge dataset of hundreds of archeo-stratigraphic boreholes was coupled with direct and indirect surveys of the main underwater archaeological sites scattered along the whole coastal sector and with the reinterpretation of bibliographic sources. Clear evidence of a differential volcano-tectonic behaviour (highlighted for the first time in this study) led us to divide the study area into three coastal stretches with homogeneous vertical ground movements. In each sector, a new relative sea-level (RSL) curve was reconstructed, by interpreting our stratigraphic and archaeological data in terms of SL markers covering a wider timespan compared to the previous studies, from the first Roman urbanization to the present day. The comparison between RSL curves and GIA models allowed estimating vertical ground movements (See Supplementary material 2) that occurred along the coast with decimetres accuracy. For each of the 5 recognized phase of uplift or subsidence, we also studied the subsequent effects in terms of coastal geomorphological change, and advantages or negative impacts on ancient human activities. We measured an overall subsiding trend that brought the RSL from −12 ± 1 m (4th century BC) to 7 ± 0.2 m during three different episodes between 5th and 15th centuries (1450–450 y BP), which was interrupted by short-lived falls (less of 100 years) of RSL. During the phases of RSL fall and/or volcano-tectonic stability, detected for the first time in the eastern and western part of the caldera (1st-2nd century AD and 3rd-4th century AD), a basinward shift of the coastline created newly emerged land even at the base of the local sea cliffs, where shore platforms emerged, favouring intense phases of urbanization on them along the Baia – Miseno sector and at the footslope of Rione Terra. This trend also favoured the closure of the Lucrino lagoon with an extended spit bar during the 2nd century BC, allowing the establishment of a large oyster farming system belonging to Sergio Orata. On the contrary, the subsiding phases resulted in the flooding of coastal areas and anthropic structures such as villas, nymphaea and ports inducing the construction of coastal protection structures. In the extreme case of Portus Julius, subsidence led to the abandonment of the military port and its move to nearby Miseno.

A modelling approach for quantifying volcanic sulphur dioxide concentrations at flight altitudes and the potential hazard to aircraft occupants

Volcanic eruptions can emit large quantities of sulphur dioxide (SO2) into the atmosphere, which can be harmful to people and the environment. Aircraft encounters with a volcanic SO2 cloud could represent a health hazard to crew and passengers onboard. In this study we have assessed concentration levels of volcanic SO2 in the atmosphere following eight historic eruptions and use four-dimensional dispersion model simulation data to calculate when and where the World Health Organisation (WHO) health protection guideline for SO2 of 500 μgm-3 over 10 minutes is exceeded. The time and area of exceedance varies and depends on the eruption characteristics: the amount, duration and height of the SO2 release. The WHO-based guideline value is exceeded for all historic eruptions considered. In several cases, the area delineated by the WHO-based guideline, here called the SO2 hazard area, can be considerably larger than the volcanic ash hazard area for the same eruption. SO2 hazard areas also often extend over a longer period of time compared to the equivalent ash advisories. For example, following the 2019 eruption of Raikoke, the SO2 hazard area reached up to 1.7 million km2 and the WHO-based guideline value was exceeded for about two weeks, while volcanic ash was considered hazardous to aviation for about five days. These results will help the aviation industry to better understand the potential risks to their passengers and crew from volcanic SO2, and aid in defining concentration thresholds for any potential volcanic SO2 forecasts for aviation.

Numerical Analysis of Low-Enthalpy Deep Geothermal Energy Extraction Using a Novel Gravity Heat Pipe Design

Geothermal energy, derived from the Earth’s internal heat, can be harnessed due to the geothermal gradient between the Earth’s interior and its surface. This heat, sustained by radiogenic decay, varies across regions, and is highest near volcanic areas. In 2020, 108 countries utilised geothermal energy, with an installed capacity of 15,950 MWe for electricity and 107,727 MWt for direct use in 2019. Low-enthalpy sources require binary systems for power production. Open-loop systems face issues like scaling, difficult water treatment, and potential seismicity, while closed-loop systems, using abandoned petroleum or gas wells, reduce costs and environmental impacts greatly. The novel geothermal gravity heat pipe (GGHP) design eliminates parasitic power consumption by using hydrostatic pressure for fluid circulation. Implemented in an abandoned well in north-east (NE) Slovenia, the GGHP uses a numerical finite difference method to model heat flow. The system vaporises the working fluid in the borehole, condenses it at the surface, and uses gravitational flow for circulation, maintaining efficient heat extraction. The model predicts that continuous maximum capacity extraction depletes usable heat rapidly. Future work will explore sustainable heat extraction and potential discontinuous operation for improved efficiency.