Search Results (130)

On 22–23 April 2025, a seismic noise survey was conducted at the Maccalube di Aragona, a mud volcano field located in Sicily (southern Italy), with the aim of characterizing the background signal associated with vent activity and the shallow subsurface structure. The experiment, named DEMETRA (DEnse MaccalubE TRomino Acquisition), was carried out within the framework of the multidisciplinary INGV-PROMUD research project, which aims to identify key indicators of mud volcano activity and potential precursors of paroxysmal events. Ambient seismic noise was recorded at 21 sites using a three-component, 24-bit digital tromograph. Measurements were conducted with a dense spatial sampling scheme covering both vent areas and peripheral zones. Preliminary data analyses included spectral estimates, computation of horizontal-to-vertical spectral ratio (HVSR) curves and evaluation of the polarization patterns. The HVSR curves do not display clear amplification peaks but rather show deamplification at specific sites. The polarization patterns exhibit spatial consistency across the vent areas. In addition, transient signals were identified in the background noise at some sites; based on their spectral and polarization characteristics, these signals are possibly associated with degassing, mud emissions, or bubbling phenomena. The dense spatial coverage of the DEMETRA experiment provides a valuable dataset for investigating subsurface properties and dynamic processes in an active mud volcano environment. Full article

The Muji Fault Zone (MJF) in the northeastern Pamir Plateau hosts a well-developed non-volcanic geothermal system, characterized by widespread hot springs and mud volcanoes—where core processes of geothermal fluids, including atmospheric precipitation recharge, shallow crustal circulation, carbonate-driven water–rock interactions, and CO₂-rich fluid discharge, are tightly coupled with regional intense crustal deformation and frequent seismic activity. We collected and analyzed 22 geothermal water samples and 8 bubbling gas samples from the MJF periphery, finding that the geothermal waters are predominantly of the HCO₃-Ca·Mg hydrochemical type, with hydrogen (δD: −103.82‰ to −70.21‰) and oxygen (δ¹⁸O: −14.89‰ to −10.10‰) isotopes indicating atmospheric precipitation as the main recharge source. The Na-K-Mg ternary diagram classified the waters as immature, reflecting low-temperature water–rock interactions in the shallow crust (<3 km), while noble gas isotopes (³He/⁴He: 0.03–0.09 Ra, Ra = 1.43 × 10⁻⁶) and carbon isotopes (δ¹³C-CO₂) confirmed fluid origin from crustal carbonate dissolution; SiO₂ geothermometry estimated thermal reservoir temperatures at 67–155 °C. Long-term monitoring (May 2019–April 2024) of Tahman (THM) and Bulake (BLK) springs revealed significant pre-seismic anomalies: before the 2023 Tajikistan Ms7.2 and 2024 Wushi Ms7.1 earthquakes, Na⁺, Cl⁻, and SO₄²⁻ concentrations showed notable negative anomalies (exceeding 2σ of background values) with synchronous trends between the two springs. Integrating these findings, a “Fault-Spring-Mud Volcano-Earthquake” fluid response model was established, providing direct evidence of deep-shallow fluid coupling in mud volcano–geothermal fluid interactions. This study enhances understanding of the dynamic evolution of non-volcanic geothermal systems under tectonic stress and clarifies the mechanisms of hydrogeochemical variations in fault-controlled geothermal systems, offering a robust scientific basis for advancing research on tectonic–fluid interactions in active fault zones of the northeastern Pamir Plateau. Full article

The Lunayyir Volcanic Field (Harrat Lunayyir), located on the western boundary of the Arabian Microplate, comprises a Quaternary volcanic region featuring approximately 150 volcanoes formed from around 700 vents. In 2009, a significant volcano-seismic event occurred, resulting in the formation of a nearly 20 km long fissure. Geophysical modeling has demonstrated that this area lies above an eruptible magma system, unequivocally confirming ongoing volcanic activity. Recent geological mapping and age determinations have further established the field as a young Quaternary volcanic landscape. Notably, the 2009 event provided critical evidence of the region’s volcanic activity and underscored the potential to connect its volcanic geoheritage with hazard mitigation strategies. The volcanic field displays diverse features, including effusive eruptions—primarily pāhoehoe and ‘a‘ā lava flows—and explosive structures such as spatter ramparts and multi-crater scoria cones. While effusive eruptions are most common and exert long-term impacts, explosive eruptions tend to be less intense; however, some events have reached a Volcanic Explosivity Index (VEI) of 4, distributing ash up to 250 km. Recognizing the geoheritage and geodiversity of the area may enhance resilience to volcanic hazards through geoconservation, educational initiatives, managed visitation, and establishment of a geoheritage reserve to preserve site conditions. Hazards associated with this dispersed monogenetic volcanic field manifest with recurrence intervals ranging from centuries to millennia, presenting challenges for effective communication. Although eruptions are infrequent, they have the potential to impact regional infrastructure. Documentation of volcanic geoheritage supports hazard communication efforts. Within the northern development sector, 26 geosites have been identified, 22 of which pertain to the Quaternary basaltic volcanic field, each representing a specific hazard and contributing vital information for resilience planning. Full article

Mount Etna has a well-documented history of frequent eruptions and seismic activity, periodically causing significant damage to urban areas. On 26 December 2018, a Mw 4.9 shallow earthquake struck the volcano’s eastern flank, severely damaging approximately 3000 buildings. The post-earthquake recovery strategy aimed to enhance community resilience by addressing the hazardous nature of the affected territory. This objective was achieved through measures such as relocation and public use transformation. In areas impacted by active faults, the relocation of damaged buildings was encouraged, while cleared zones were repurposed for public use, transformed into gardens and open-air parking spaces. Despite these efforts, some relocated individuals experienced psychological distress. To address this challenge, government planners played a pivotal role in disseminating scientifically accurate information, raising public awareness, and facilitating adaptation. The approach implemented on Etna was later adopted in other post-earthquake recovery programs in Italy, evolving into a replicable strategy for risk mitigation in disaster-prone areas. Full article

Volcano-tectonic seismic events (VT) are quite rare at Stromboli, numbering about ten events per year and generally with low magnitude. Using a dataset of 98 events from the 2005–2024 period, we report an improved relocation of VT events here. Relocated earthquakes are mainly distributed on the island and in an area located SSW of Stromboli. These VT events are related to the activation of seismogenic structures by a stress increase related to magma ascent. The shallowest seismicity (4–5 km) is positioned under the Stromboli summit, with a high occurrence in 2006–2007 and in 2019–2024, suggesting a major recharge of the HP magma reservoir. The deepest VT seismicity affects a depth of 7–12 km located in the submerged edifice SSW of the summit and is attributable to the dynamics of the LP magma reservoir, which was more active in 2006–2014 and much less so in the successive years. The increase in the occurrence rate of VT shallow seismicity seems to precede the most significant Stromboli activities, such as the 2007 and 2024 lava effusions followed by paroxysms. For these episodes, VT seismicity would appear to indicate a recharging in the first 4–5 km during the months preceding them, thereby representing a medium–short-term warning signal. Full article

The advanced determination of the type (foreshock–aftershock–swarm) of an ongoing seismic cluster is quite challenging; only retrospective solutions have thus far been proposed. In the period of January–March 2025, a seismic cluster, recorded between Santorini volcano and Amorgos Island, South Aegean Sea, caused considerable social concern. A rapid increase in both the seismicity rate and the earthquake magnitudes was noted until the mainshock of M_L = 5.3 on 10 February; afterwards, activity gradually diminished. Fault-plane solutions indicated SW-NE normal faulting. The epicenters moved with a mean velocity of ~0.72 km/day from SW to NE up to the mainshock area at a distance of ~25 km. Crucial questions publicly emerged during the cluster. Was it a foreshock–aftershock activity or a swarm of possibly volcanic origin? We performed real-time discrimination of the cluster type based on a daily re-evaluation of the space–time–magnitude changes and their significance relative to background seismicity using earthquake statistics and the topological metric betweenness centrality. Our findings were periodically documented during the ongoing cluster starting from the fourth cluster day (2 February 2025), at which point we determined that it was a foreshock and not a case of seismic swarm. The third day after the M_L = 5.3 mainshock, a typical aftershock decay was detected. The observed foreshock properties favored a cascade mechanism, likely facilitated by non-volcanic material softening and the likely subdiffusion processes in a dense fault network. This mechanism was possibly combined with an aseismic nucleation process if transient geodetic deformation was present. No significant aftershock expansion towards the NE was noted, possibly due to the presence of a geometrical fault barrier east of the Anydros Ridge. The 2025 activity offered an excellent opportunity to investigate deciphering the type of ongoing seismicity cluster for real-time discrimination between foreshocks, aftershocks, and swarms. Full article

The South Shetland Islands and Antarctic Peninsula (SHETPENANT region) constitute a geodynamically active area shaped by the interaction of major tectonic plates and active magmatic systems. This study analyzes GNSS time series spanning from 2017 to 2024 to investigate surface deformation associated with the 2020–2021 seismic swarm near the Orca submarine volcano. Horizontal and vertical displacement velocities were estimated for the preseismic, coseismic, and postseismic phases using the CATS method. Results reveal significant coseismic displacements exceeding 20 mm in the horizontal components near Orca, associated with rapid magmatic pressure release and dike intrusion. Postseismic velocities indicate continued, though slower, deformation attributed to crustal relaxation. Stations located near the Orca exhibit nonlinear, transient behavior, whereas more distant stations display stable, linear trends, highlighting the spatial heterogeneity of crustal deformation. Stress and strain fields derived from the velocity models identify zones of extensional dilatation in the central Bransfield Basin and localized compression near magmatic intrusions. Maximum strain rates during the coseismic phase exceeded 200 $\mathrm{\nu }$strain/year, supporting a scenario of crustal thinning and fault reactivation. These patterns align with the known structural framework of the region. The integration of GNSS-based displacement and strain modeling proves essential for resolving active volcano-tectonic interactions. The findings enhance our understanding of back-arc deformation processes in polar regions and support the development of more effective geohazard monitoring strategies. Full article

The Davie Fracture Zone (Davie FZ)—among the longest offshore transform systems in East Africa—mediated Madagascar’s southward displacement following Gondwana’s Early Jurassic breakup. This giant structure has a distinct topography and gravity field signals. However, it is buried by thick sediments in its northern segment offshore Tanzania, hindering understanding of the internal structures and their origin. In this study, we applied 2-D multichannel seismic to analyze the structural characteristics and evolution of the Davie FZ. The Davie FZ is located in the oceanic domain, which is bordered by the landwards-dipping overthrust fault at the continent–ocean boundary. Volcano sediments atop the basement with undulating Moho reflection below depict a typical oceanic domain. Distinct compressive deformation characterized by the crustal undulation of around 40 km wavelength forms folded oceanic crust, and Late Jurassic sediments onlap onto the crest of the folded basement. The Davie FZ is localized in a corridor with the thickened oceanic crust and is presented by positive flower structures with faulted uplifted basement and deepened Moho. The Davie FZ evolved from a proto-transform fault located in Gondwana before the spreading of the West Somali Basin. During the Late Jurassic, a kinematic change shifted the spreading direction from NW–SE to N–S, resulting in a strike-slip of the Davie FZ and contemporaneous transpressional deformation offshore Tanzania. The Davie FZ is an excellent case to understand the tectonic-magmatic process forming this transform margin. Full article

Azerbaijan is known as a hydrocarbon-rich region for its extensive mud volcanoes and complex tectonic settings. In this research, we analyzed a long-term InSAR time-series from Sentinel-1 SAR data spanning January 2017 to October 2024, which revealed the dynamics of active deformation and mud volcanoes. The study area, with its unique geological complexity characterized by rapid eruptions, subsurface pressure, and fault systems, is a one-of-a-kind natural laboratory for examining the interplay between tectonics and mud volcano activity. Based on extensive data collection, the results showed significant deformation on the primary mud volcanoes, such as Ayazakhtarma and Akhtarma-Pashaly. These patterns, characterized by observed subsidence and uplift, result from subsurface pressure fluctuations and hydrocarbon migration. Furthermore, the examination has demonstrated evidence of temporal deformation episodes intricately linked to the periodic buildup and release of subsurface pressures. A significant result of our study was the reactivation of faults and high deformation rate in almost all observed mud volcanoes during the February 2023 Türkiye Kahramanmaraş earthquakes (Mw 7.8 and 7.6). This dynamic far-field triggering effect reactivated faults and induced widespread deformation. This study indicates that the far-field triggering effect has uncovered deformation patterns that persist for several months after the earthquakes, reflecting prolonged subsurface adjustments. The findings demonstrate that mud volcanoes are subsurface fluid dynamics and tectonic stress indicators and have significant practical implications. Overall, the results provide important insights into the reaction of hydrocarbon-rich regions to seismic energy that can be directly applied to improve regional seismic hazard assessments and tectonic studies. By combining different geodetic data with geological interpretations, this work emphasizes the implication of monitoring hydrocarbon-rich regions like Azerbaijan to assess natural hazards and subsurface dynamics, making the research highly relevant and applicable. Full article

Geothermal resources represent one of the most vital renewable energy sources, offering substantial development potential within the energy sector. Wudalianchi, renowned as one of China’s prominent volcanic clusters, has undergone extensive underground volcanic activities, suggesting a promising capacity for geothermal resource accumulation. This paper is the first to apply the cross-gradient gravity-magnetic joint inversion method to study the shallow structures in the Laoheishan Volcano and surrounding areas of Wudalianchi, based on high-precision measured gravity and magnetic data. The inversion results indicate the presence of a rock body at a depth of approximately 2 km beneath the Laoheishan and Bijiashan regions, which simultaneously exhibits characteristics of low density, high magnetization, and low seismic velocity. Integrating previous research findings, the rock body is interpreted as basalt formed during magmatic activity, retaining remanent magnetism. Furthermore, the rock body contains fractures filled with fluids, thereby excluding the possibility of a shallow magma chamber or dry hot rocks beneath the Laoheishan area. These rock bodies are interconnected at depth and align with the NE and SE fault directions in the Wudalianchi area, confirming that these faults govern the region’s volcanic activities. The inversion results, from the perspectives of density and magnetic susceptibility, elucidate the material distribution in the shallow subsurface of the Laoheishan and surrounding areas, providing new evidence for further exploration of geothermal resources in the region. Full article

Edgecumbe, a dormant volcano located on Kruzof Island in the southeastern part of Alaska, USA, west of the Sitka Strait, has exhibited increased volcanic activity since 2018. To assess the historical and current intensity of this activity and explore its relationship with seismic events in the surrounding region, this study utilized data from the ERS-1/2, ALOS-1, and Sentinel-1 satellites. The Permanent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) and Small Baseline Subset InSAR (SBAS-InSAR) techniques were employed to obtain surface deformation data spanning nearly 30 years. Based on the acquired deformation field, the point-source Mogi model was applied to invert the position and temporal volume changes in the volcanic source. Then, by integrating seismic activity data from the surrounding area, the correlation between volcanic activity and earthquake occurrences was analyzed. The results indicate the following: (1) the coherence of interferograms is influenced by seasonal variations, with snow accumulation during the winter months negatively impacting interferometric coherence. (2) Between 1992 and 2000, the surface of the volcano remained relatively stable. From 2007 to 2010, the frequency of seismic events increased, leading to significant surface deformation, with the maximum Line-of-Sight (LOS) deformation rate during this period reaching −26 mm/yr. Between 2015 and 2023, the volcano entered a phase of accelerated uplift, with surface deformation rates increasing to 68 mm/yr after August 2018. (3) The inversion results for the period from 2015 to 2023 show that the volcanic source, located at a depth of 5.4 km, experienced expansion in its magma chamber, with a volumetric increase of 57.8 × 10⁶ m³. These inversion results are consistent with surface deformation fields obtained from both ascending and descending orbits, with cumulative LOS displacement reaching approximately 210 mm and 250 mm in the ascending and descending tracks, respectively. (4) Long-term volcanic surface deformation, changes in magma source volume, and seismic activity suggest that the earthquakes occurring after 2018 have facilitated the expansion of the volcanic magma source and intensified surface deformation. The uplift rate around the volcano has significantly increased. Full article

Active volcanic calderas often experience significant ground deformation, characterized by uplift and subsidence, typically with a radial or elliptical pattern centered on the caldera. However, the detection of small second-order anomalies within the main deformation pattern can provide critical insight into impending eruptions and/or hazardous structural and volcano-tectonic features. In this study, we present a simple but novel method for detecting and interpreting second-order deformation anomalies at Campi Flegrei caldera by filtering the primary, radial deformation signal observed during volcanic unrest phases. For this purpose, we used a procedure based on the polynomial fit of vertical displacement data, assuming that they depend only on the distance from the deformation center. By subtracting the best fitting radial deformation from the observed vertical displacement, we generated an anomaly map that highlights sectors with unexpected deformation patterns. We applied the proposed procedure to analyze the ground deformation at the Campi Flegrei caldera (Italy) that occurred from 2016 to 2021, by using MT-InSAR data from Sentinel-1. Coeval GPS datasets were also used for cross-checking the obtained results. The results of this analysis show a pronounced NE-SW alignment that separates sectors with different uplift trends. It highlights a primary volcano-tectonic structure potentially linked to high seismic hazard. This method, after further investigation, can provide a valuable tool for improving hazard assessment and understanding the structural dynamics of calderas during unrest phases, with implications for improving preparedness in densely populated volcanic regions. Full article

Following the abrupt geochemical and geophysical variations that occurred on the island of Vulcano in September 2021, the search for previous multidisciplinary data on decades-long time spans became necessary to contextualize the newly recorded anomalous variations, which represented a serious threat for the local population. Our analyses of ‘vintage’ reports, old documents and analogue seismograms, broaden our understanding of crustal seismic activity. The results unravel the predominant role of Vulcano’s hydrothermal system with respect to tectonic processes in the generation of seismicity in the analyzed sector. Earthquakes were generally located offshore and achieved a maximum M4.6. A 2D strain release map and DBSCAN application highlight seismogenic volumes to the NW, SW and E offshore of the island and trending NNW-SSE inshore, in agreement with structural patterns. Two major volcano unrests in 1985 and 1988 had seismicity mostly confined to the island. In comparison, the longer duration and typology of seismic signals recorded between 2021 and 2022 make this latest episode peculiar in the context of Vulcano’s past seismic activity. Full article

Submarine slides, gas hydrates, shallow gas, and volcanoes considered to be potential geohazards have been well delineated using three-dimensional (3D) seismic data and well log data in the Pearl River Mouth Basin, South China Sea. Seismic characteristics, distribution maps, and controlling factors of these geohazards have been well analyzed showing the influence of regional tectonics and sedimentary processes. Recently, shallow gas and gas hydrates are confirmed by drilling expeditions, which are considered important unconventional resources. Moreover, the mapped features of various geohazards show the spatial overlays and that they are connected each other. To delineate well the relationships between gas hydrates, shallow gas, and the potential geological features such as submarine slides, gas chimneys, faults, and volcanoes, the seismic attributes and interpretations are displayed using 3D seismic data to show the interplay between them. Gas hydrates and shallow gas occur and are widely distributed above sills, volcanoes, gas chimneys, and faults within the submarine slides and migrating canyon because large amount of hydrocarbon gas can migrate from the deep layer to the shallow layer along different pathways. This study aims to show the correlation among various geological bodies and their effects on shallow gas and gas hydrate distributions. Full article

We built a regional geological section founded upon the assessment of a seismic line in the Volturno basin, which is situated on the northern Campania continental shelf of the Tyrrhenian margin of Southern Italy. This section has been integrated with multichannel seismic data of Zone E (ViDEPI project) to highlight its relationships with the Massico structure. In the Volturno basin, there are four Pleistocene to Holocene units, recognized based on seismic analysis lie above deep seismo-stratigraphic units, related to Campania Latium carbonate platform and The Frosinone Flysch. Onshore and offshore seismic data, calibrated with lithostratigraphic correlation, have displayed the seismo-stratigraphic framework, including both sedimentary and volcanic seismo-stratigraphic units. Of these, the lavas associated with the Northern Campania Volcanic Zone’s Villa Literno volcano are associated with seismic unit 2a. Seismo-stratigraphic data has shown the offshore prolongation of the Massico structure, as involved by normal faults and flower structures. The whole-data interpretation suggests that the tectonic activity acted in correspondence to normal faults, which have controlled half-graben and interposed structural highs, fitting to the regional geological setting of the continental margin. Full article