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Preferential Fluids Ascent Paths Revealed by Coupling Chemical, Electrical and Magnetic Methods: Insights for Risk Mitigation in a Long‐Dormant Volcanic Province (Monts Dore, France)
No full textRisk mitigation in long‐dormant volcanic provinces is often hampered by the lack of information
about potential eruptive scenarios. It is the case of the Monts Dore volcanic province (France), where the last
eruptive sequence occurred about 7,000 years ago in lake Pavin. While the main recent interests focused on
potential limnic eruption from the lake due to CO2 storage in the deep‐water layer, no information is provided
about the assessment of lava flow hazards. In this study, an innovative approach is led by coupling geochemical
(soil CO2 degassing) and geophysical (magnetism, electrical resistivity tomography) surveys to identify
(hidden) areas and structures marked by fluid circulation and alteration processes. These preferential paths for
current fluid ascent may be considered, due to their high permeability, as potential paths for magma ascent in
case of volcanic unrest. In such a hypothetical scenario, a priori lava flow modeling can help in discriminating
the most exposed infrastructural areas and thus provide new insights to local authorities regarding land use. Our
results highlight that, even in long‐dormant volcanic provinces, common tools used on active volcanoes for risk
assessment may be applied to improve relevant risk mitigation strategies.PublishedJCR Journa
Scientific response to the 2021–2022 seismic swarm in the Monts Dore volcanic province (France): structural insights from punctual surveys (1/2)
No full textLong-dormant volcanic provinces remain excellent proxies in studying active edifices. The
Monts Dore volcanic province (French Massif Central) has been recently the site of a unique seismic
episode. Geophysical surveys were conducted at different horizontal and vertical spatial scales. Magnetic
anomalies highlight mechanical heterogeneities consistent with the regional tectonic context.
Low-conductive structures imaged suggest the presence of fluid rising along main paths at various
depths. Although we cannot strictly exclude a purely tectonic explanation, our data seem to support
the origin of seismicity as being linked to the injection of fluids at depth controlled by internal structural
constraints.PublishedJCR Journa
Scientific response to the 2021–2022 seismic swarm in the Monts Dore volcanic province (France): dynamic insights from temporal surveys (2/2)
No full textPublishedJCR Journa
Assessing the Impact of the October 2020 Capena Earthquake on the Lago Puzzo Sinkhole (San Martino Valley, Rome, Italy): Seismological, InSAR, and Geophysical Evidence of Possible Causal Relationships
No full textIn October 2020, a low-magnitude earthquake struck near the village of Capena, approximately 30 kilometers north of Rome. This seismic event was particularly remarkable due to its shallow hypocenter and the complete absence of aftershocks. Additionally, both during and after the event, residents reported hearing loud rumbling noises on multiple occasions in the village and surrounding rural areas. The earthquake's epicenter is located in a sinkhole-prone region intersected by major infrastructure, including a high-speed railway, high-voltage power lines, and a provincial road. Given these conditions, public authorities and regional Civil Protection agency closely monitored the area, prompting a comprehensive investigation. The study adopted an interdisciplinary approach to assess the stability of sinkhole-prone zones and identify any geological changes potentially triggered by the earthquake. A key focus of the research was the ''Lago Puzzo,'' a well-documented example of multiphase, still active, sinkhole evolution within the San Martino Valley, alongside other similar extinct features in the area. The investigation integrated three primary methodologies: spectral analysis of seismic data to characterize the October 2020 event; remote sensing (SAR) using InSAR analysis to map ground displacement; geophysical surveys (ERT) to reveal subsurface structures. Although the study found no direct correlation between the earthquake and the evolution of Lago Puzzo, the results provide valuable insights into the current deformation state of the sinkhole and offer projections for its potential future development. Ultimately, this research represents a significant step forward in refining hazard assessment methods for the region.PublishedJCR Journa
Contrasting dynamics of past climate states and critical transitions via dimensional analysis
No full textWhile past major climate transitions can be unequivocally identified, understanding of underlying mechanisms and timescales remains limited. We employ a dimensional analysis of benthic stable isotope records across different timescales to uncover how Cenozoic climatic fluctuations are associated with changes in the number of feedbacks and mechanisms involved. Our analysis indicates that warmer and colder climates respond substantially differently to orbital forcing. Notably, large numbers of feedbacks dominated during the Icehouse (3.3 Ma to present) state at obliquity and eccentricity timescales, and during the Warmhouse (66-56 Ma and 47-34 Ma) and Hothouse (56-47 Ma) states at precession timescales. During the Coolhouse (34-3.3 Ma) state the number of active feedbacks was low and had no dominant timescale. Coupling between climate signals that affect oxygen and carbon isotope records appears high only in the Icehouse state, and low to absent in all other states. We also find that anomalously high active feedback numbers and very high coupling occurred across all timescales during the Paleocene-Eocene Thermal Maximum (PETM, 56 Ma), which suggests a complete system perturbation. In conclusion, our findings challenge the notion of a simple and unique conceptual model of interconnected feedbacks in reproducing Cenozoic paleoclimate variability, given that different numbers of active feedbacks with different levels of coupling governed different timescales between climate states, which then affected the inherent (in-)stability of each climate state.PublishedOSA2: Evoluzione climatica: effetti e loro mitigazioneJCR Journa
Reconstructing the volcanic history of the Ulukıs ¸la Caldera: A collapse structure within the Hasandag Volcanic Complex, Central Anatolia (Turkey)
No full textThe Ulukıs ¸la Caldera is a collapse structure within the active Hasandag Volcanic Complex (Central Anatolia), situated along the southern branch of the Tuz Gölü Fault Zone (TGFZ). This study aims to reconstruct the volcanic history of the Ulukıs ¸la Caldera by characterising its associated pyroclastic deposits using tephrostratigraphy, glass chemistry (major and trace elements), and geochronological data (40 Ar/ 39 Ar and U-(Th)-Pb). Our findings reveal that the Ulukıs ¸la Caldera has undergone at least three major explosive rhyolitic eruptions, which formed the pyroclastic deposits of the Yenipınar Eruption (~442 ka), the Belbas ¸hanı Eruption (~400 ka), and the Ulukıs ¸la Eruption (~326 ka). The Yenipınar unit was produced by an unsteady eruption column originating from paleo-Ulukıs ¸la volcanic structure, that deposited pumice fallout layers and interbedded pyroclastic density current (PDC) deposits. The Belbas ¸hanı Eruption began with a Plinian column that deposited the Belbas ¸hanı Pumice fallout. This phase was followed by the emplacement of thick PDC deposits and co-ignimbrite lithic lag breccias during the collapse, which ultimately led to the formation of the Ulukıs ¸la Caldera. The volume of the Belbas ¸hanı deposits, including the pumice fallout and the caldera-forming ignimbrite, could reach up to 10 km 3 DRE (Dense Rock Equivalent), corresponding to an eruption of magnitude ~6. The Ulukıs ¸la Pumice resulted from a post-caldera eruption, which did not generate PDCs. The Ulukıs ¸la Caldera exhibits an elongated morphology, which is strongly influenced by the NW-SE alignment of the TGFZ. Based on this morphology and the regional tectonic setting, we conclude that the Ulukıs ¸la Caldera is a strike-slip/graben caldera. Reconstructing the volcanic history of this newly identified caldera is essential for enhancing our understanding of the Hasandag Volcanic Complex. Our findings offer valuable context for future eruptive behaviour, improving the hazards assessment for potential caldera collapses, and contribute to mitigating associated risks.PublishedJCR Journa
Predominant orbital forcing on Asian hydroclimate during the Miocene Climatic Optimum
No full textThe Miocene Climatic Optimum (MCO), spanning from ca. 17 Ma to 14 Ma, marks a pivotal interval in global climate history with elevated greenhouse gas levels and a 3–7 °C increase in global temperatures, disrupting the long-standing Cenozoic cooling trend. However, the dynamics that drove the MCO in the continental realm are not well understood. The driving forces may have conditioned regional scale climate phenomena, such as shifts from an arid to humid environment with a significant temperature rise due to elevated greenhouse gases. Terrestrial outcrops in eastern Asia are particularly valuable for studying the MCO's continental impacts due to their exceptional preservation of orbital-scale sedimentary cycles and sensitivity to monsoonal dynamics, which are pivotal for disentangling hydroclimate-orbital linkages. Notably, the hydrological circulation and orbital influence during the MCO in eastern Asia are still understudied. Employing magneto-cyclostratigraphic chronology, we analyzed samples from a 120-m-thick outcrop section in inland Asia, revealing detailed, orbital-scale, terrestrial responses to the MCO. Based on cyclostratigraphic analysis, our findings emphasize the pronounced influence of two orbital cycles: the dominant 405-k.y. eccentricity and the subtler 173-k.y obliquity band. Based on the magnetic susceptibility, Fe content, and Rb/Sr ratio of rock samples, we concluded that eccentricity and obliquity climate control shifted the summer movement of the Intertropical Convergence Zone in East Asia, impacting northward moisture transport. Significantly, we identified six drought events based on variations in magnetic susceptibility, geochemical proxies (i.e., Fe content and Rb/Sr ratio), and correlation with global phenomena, such as distinct δ13C positive excursions (such as the Monterey Excursion), Antarctic cooling phases (Mi-events), global sea surface temperature changes, and sea-level fluctuations. Our results provide insights into climate variations on both regional and global scales, with implications for past and potential future scenarios.PublishedOSA2: Evoluzione climatica: effetti e loro mitigazioneJCR Journa
Unveiling Tectonic Complexities in the 2024 Hualien (eastern Taiwan) Earthquake Sequence Using GNSS and InSAR Data
No full textTaiwan, located at the convergent boundary between the Philippine Sea and Eurasian plates, is one of the most seismically active regions globally, with convergence rates reaching 80-90 mm/yr. The Longitudinal Valley suture zone in eastern Taiwan, accommodating ~30 mm/yr of NNW-SSE shortening, hosts two major reverse fault systems: the E-dipping Longitudinal Valley Fault (LVF) and the W-dipping Central Range Fault (CRF). These faults exhibit complex interactions, particularly in the northern sector of the Longitudinal Valley, where cross-cutting relationships and evolving tectonic dynamics generate significant seismotectonic complexity.
The 2 April 2024 MW 7.4 Hualien earthquake, the strongest instrumentally recorded event near Hualien since the 1951 sequence, exemplifies this complexity. Previous seismic events in this region have been associated with ruptures on both E- and W-dipping faults, reflecting the dynamic interplay between these systems. To investigate the faulting processes and source parameters of this sequence, we analyzed an extensive geodetic dataset, integrating Global Navigation Satellite Systems (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) observations. Elastic dislocation modeling was applied to constrain the rupture geometry and evaluate the interaction between fault segments. GNSS and InSAR data from the 2024 event reveal a rupture pattern involving multiple fault segments, consistent with observations of focal mechanisms, aftershock distributions, and long-term moment release patterns. Although simple single-fault models (e.g., an E-dipping Longitudinal Valley Fault or a W-dipping Central Range Fault) can explain the geodetic data, a composite fault model, incorporating multiple segments, better accounts for the observed displacements, seismicity, and the complex structure of the northern Longitudinal Valley. Our findings provide new insights into the seismogenic processes and fault dynamics underlying this significant seismic event. They highlight the evolving tectonic setting of eastern Taiwan and contribute to the understanding of the processes driving seismotectonic complexity in one of the most tectonically active regions of the world.Publishe
A novel simplified ground-based thermal infrared (TIR) system for volcanic plume geometry, SO<sub>2</sub> columnar abundance, and flux retrievals
No full textIn the last few decades, volcanic monitoring using remote sensing systems has become an essential tool to investigate the effects of volcanic activity on environment, climate, human health, and aviation, as well as to give insights into volcanic processes. Compared to satellite measurements, ground-based instruments offer continuous spatial and temporal coverage capable of providing highresolution and high-sensitivity data. This work presents a new simplified prototype of a thermal
infrared (TIR) system (named “VIRSO2”). The instrument comprises three cameras, one working in the visible spectrum and two in the TIR (8–14 μm). In front of one of the two TIR cameras, an 8.7 μm filter is placed. The system is designed for the detection of volcanic emission, geometry estimation, determining the columnar content of SO2 and ash, and SO2 flux retrievals. The retrieval procedures developed are detailed starting from the geometric characterisation with wind direction correction, the calibration by considering the effects of filter multireflections and temperature, and the SO2 mass by exploiting MODTRAN radiative transfer model (RTM) simulations. The SO2 flux is then computed by applying the traverse method, with the plume speed obtained from the wind speed at the crater altitude. As test cases, the measurements collected at Etna Volcano (Italy) on 1 April 2021 during a lava fountain episode and 30 August 2024 during a quiescent phase have been considered. The results show that the system can provide reliable information on plume detection, altitude, and SO2 flux. Its simplicity, its low cost, and the possibility of carrying out measurements at a safe distance from the vent during both the day and the night make this system ideal for realtime monitoring of volcanic emissions, thus helping to provide information on the state of activity of the volcano and therefore to mitigate the effect that these natural phenomena have on humans and the environment.PublishedJCR Journa
Origin and Evolution of the Late Middle Pleistocene Trachytes in the Changbaishan Tianchi Volcano (China/North Korea): Insights from Mineralogy, Geochronology and Geochemistry
No full textCenozoic trachytes are characteristic of some active volcanic fields in China. In particular, the origin and
mechanisms of the evolution of trachytes from the Tianchi (Changbaishan) volcano (TV, China/North Korea) are poorly
known. Here, we present new geochronological, geochemical and isotopic data on two trachytic suites outcropping on the
northern and southern upper slopes of TV. Detailed zircon laser ablation-multicollector-inductively coupled plasma-mass
spectrometry (LA-MC-ICP-MS) U-Pb dating, Rb-Sr isochron dating of plagioclase and hornblende, 40Ar/39Ar chronology
with mineral chemistry, whole-rock element and Sr-Nd-Pb isotope data are used to explore their origins and evolutionary
mechanisms during the late Middle Pleistocene. Our data indicate that the trachytes mainly consist of sanidine, orthoclase
and plagioclase, with minor albite, quartz and hornblende. They formed at 0.353–0.346 Ma (lava flow from the northern
slope) and 0.383–0.311 Ma (lava flow from the southern slope), respectively. The TV trachytes are characterized by high
K2O/Na2O and AR values, with low A/CNK and Mg# values. They are enriched in rare earth elements (REEs; except Eu),
depleted in Sr and Ba, crystallizing at 742–858°C. The TV trachytes have high (87Sr/86Sr)i values (0.70776–0.71195),
positive εNd(t) values (0.61–2.93) and radiogenic 206Pb/204Pb values (17.515–17.806). These values are similar to those of
the Pleistocene and Holocene TV trachytes. Geochemical data indicate that they were formed by fractional crystallization
from a basaltic melt and assimilated upper crust material. The trace element pattern of the studied trachytes is consistent
with an evolution from basaltic melts representative of an enriched mantle source. The vent from which the trachytic
magma was erupted probably collapsed inside the caldera during the TV ‘Millennium’ eruption (ME) in 946 AD. The
contemporaneous emission of basaltic and trachytic magma during the Middle–Late Pleistocene suggests the coexistence of
fissural basaltic volcanism and central-type trachytic volcanism, the latter of which was associated with a magma chamber
in the upper crust during the TV cone-construction stagePublishedJCR Journa