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Study of well data reveals fluid pressure distribution and origin in the upper crust of the Irpinia region (Southern Apennines, Italy)
No full textThis study investigates subsurface pore pressures in the Irpinia region of southern Apennines, Italy, one of the central Mediterranean areas with the highest seismic activity. The Apennine thrust belt consists of stacked thrust sheets formed from both deep-and shallow-water environments during the pre-orogenic phase and later involved in the Neogene compressional phase. In the ongoing post-orogenic phase, the region is experiencing an extensional tectonic regime, as evidenced by the 1980 Ms. 6.9 normal fault Irpinia earthquake. Eleven exploration wells drilled to depth of 1.7-5.9 km intersect the main tectonostratigraphic units of the chain, providing valuable data on drilling mud weights and fluid chemical features, allowing for the reconstruction of vertical pore pressure trends and fluid circulation through the upper crust up to nearly 6 km of depth. The data analysis reveals that the carbonate platform and basin Meso-Cenozoic deposits generally exhibit hydrostatic or nearly hydrostatic conditions in the upper 2-4 km depth. However, moderate to high overpressure gradients are observed in Meso-Cenozoic basin sequences, Messinian evaporites, tectonic mélange, and foredeep Pliocene shales. These overpressures are typically associated with reverse faults and are not correlated with occurrences of gas. Conversely, slight overpressure gradients at shallower depths are related to shaly lithologies containing gas traces. Notably, the pressure profile of San Gregorio Magno-1 well, intersecting the causative fault of the 1980 earthquake, suggests a uniform distribution of fluids throughout intensively fractured nappes, including carbonate platform units and deep-water basin formations. Moreover, wells that penetrated the buried platform carbonates, known as Apulian carbonates, display hydrostatic or low overpressure gradients, even when overpressured shales seal the carbonate reservoirs, challenging previous seismological interpretations of overpressured Apulian carbonates. Finally, the analysis of diffusion mechanisms has provided insights into the timing of the geological disturbance that caused the locally observed overpressures and their maintenance.PublishedJCR Journa
Structural development and seismogenesis in the Messina Straits revealed by stress/strain pattern above the edge of the Calabrian slab (Central Mediterranean)
No full textThe Messina Straits is a narrow marine basin shaped by regional-scale uplift and localized subsidence driven by crustal faulting along the diffuse Africa-Eurasia convergent plate boundary. Catastrophic earthquakes have struck the region, most notably the 1908 Mw 7.1 Messina event. However, the causative fault(s) and the geodynamic drivers of this deformation remain unclear. In this study, we use seismological and marine geophysical data to investigate neotectonic activity within the broader central Mediterranean geodynamic framework. By analysing relocated hypocentres, principal stress conditions and deformation patterns, we explore the link between seismicity and tectonic features identified in seismic reflection profiles and morphobathymetric maps.
Our findings reveal a significant variation in seismogenic thickness and earthquake distribution across the Messina Straits suggesting spatially variable tectonic processes. Stress tensors show a composite deformation pattern, from predominantly extensional deformation between 6 and 20 km, to more heterogeneous deeper deformation (40–80 km) that includes compressional mechanisms.
We interpret our fault structure data in the Messina Straits as reflecting the shallow crustal response to active tectonics occurring within a large deformation zone oriented along and above the Calabrian slab edge. This zone is characterized by several strike slip faults, including the Ionian fault in the Ionian Sea and the Capo Peloro fault in the southern Tyrrhenian Sea, which together bound the extensional domain of the Messina Straits.
Based on our analysis, we propose that present-day subsidence and seismogenesis in the Messina Straits are strongly influenced by deformation along these strike-slip segments, primarily driven by the relative motion between Africa and Eurasia, in combination with tensile forces deriving from lateral variations in gravitational potential energy.PublishedOST1 Alla ricerca dei Motori GeodinamiciJCR Journa
Cosmogenic helium signatures at Deception Island volcano (Antarctica): geochronological implications for its eruptive history
No full textCosmogenic nuclei production for dating the Earth surface exposure of rock/mineral samples,
especially 3He, is a robust technique in geochronology. We describe its application to constrain the
ages of key eruptive episodes of the volcanic history of Deception Island (Antarctica): (i) the volcanic
products of the island formed before the caldera collapse (pre-caldera material); and (ii) the caldera-
forming event (syn-caldera material). High 3He/4He ratios (up to 910 RA; RA
=
1.39
×
10–6) in the crystal
structure of olivine phenocrysts measured through total fusion He release are much higher than the
magmatic values previously obtained in the inclusions of the same olivines obtained by hydraulic
crushing. Such high values indicate a cosmogenic origin and reveal an age of c. 4 Ma for the pre-caldera
material, and c. 4.6 ka and 170 ka for the syn-caldera deposits. The result of c. 4.6 ka for the caldera
collapse episode is consistent with previous age estimations based on tephrochronology, whereas the
c. 170 ka result reveals the presence of pre-caldera olivines embedded in the syn-caldera deposits that
experienced less exposure to cosmic rays compared to the samples with ages of 4 Ma. This oldest age
estimate represents the first quantitative geochronological approach attempting to date Deception
Island formation.PublishedOSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametric
Materials for a Catalogue of Italian Earthquakes. Earthquakes in the Treviso and Belluno area between the 18th and 20th centuries
No full textRiassunto
Da quasi venti anni la comunità dei sismologi storici italiani svolge un ampio e articolato programma di ricerche per aggiornare e migliorare la base di dati macrosismici con cui i compilatori del catalogo sismico nazionale possono calcolare parametri epicentrali sempre più ben vincolati e affidabili.
Tra le iniziative realizzate ci sono: studi approfonditi di singoli terremoti, analisi di dettaglio delle “storie sismiche” di singole località/aree, e campagne su vasta scala miranti a i) produrre studi preliminari (o “speditivi”) per tutti i terremoti al di sopra della soglia di danno che ne siano ancora privi, ad ii) aggiornare/approfondire quelli tra gli studi esistenti che sono più datati e/o preliminari e ad iii) individuare e studiare il maggior numero possibile di terremoti al di sopra della soglia del danno ma ancora “sconosciuti” alla sismologia storica e quindi al catalogo sismico nazionale. Il presente lavoro raccoglie risultati delle ricerche svolte su otto terremoti localizzati nelle attuali Province di Treviso e Belluno tra il 1709 e il 1949. Sette di essi sono inclusi nella versione corrente del catalogo CPTI15 a partire da studi di riferimento preliminari; l’ottavo e più recente rientra nella categoria dei terremoti “negletti”, quelli cioè che non essendo stati inclusi per errore nel catalogo parametrico di riferimento negli anni '80 [Postpischl, 1985] non sono stati recepiti nella versione attuale del catalogo parametrico. Il lavoro si pone in continuità con un precedente studio della sismicità “minore” dell’Asolano, insieme al quale contribuisce a un sensibile miglioramento delle conoscenze sulla sismicità storica delle Prealpi venete e friulane.
Abstract
For almost twenty years, the Italian community of historical seismologists has been developing a wide and articulated research programme for updating and improving the macroseismic database used by compilers of the national earthquake catalogue to calculate increasingly accurate and reliable epicentral parameters. The initiatives carried out include: indepth studies of single earthquakes, detailed reconstructions of the ‘seismic histories’ of single localities/areas, and large scale study campaigns. These aimed at i) conducting preliminary (or ‘expeditious’) studies for historical earthquakes above the damage threshold that currently lack them, ii) updating or improving outdated or preliminary data, and iii) identifying and studying as many earthquakes as possible that exceeded the damage threshold but still ‘unknown’ to historical seismology and hence to the national seismic catalogue.
The present work gathers the results of research on eight earthquakes located in the present Provinces of Treviso and Belluno between 1709 and 1949. Seven of these are included in the current version of the CPTI15 catalogue based on preliminary reference studies. The eighth and most recent one, instead, falls into the category of ‘neglected’ earthquakes, that is, those that were mistakenly excluded from the parametric reference catalogue in the 1980s [Postpischl, 1985] and that, to date, remain absent from the current version of the parametric catalogue. The work is in continuity with a previous study of ‘minor’ seismicity in the Asolo area and, together with it, makes a significant contribution to advancing the knowledge of the historical seismicity of the Veneto and Friuli PreAlps.PublishedOST1 Alla ricerca dei Motori GeodinamiciJCR Journa
Ice mass discharge through the Antarctic subglacial hydrographic network as a trigger for cryoseismicity
No full textWe analyse seismic time series collected during experimental campaigns in the area of the David Glacier, Victoria Land, Antarctica, between 2003 and 2016. We observe hundreds of repeating seismic events, characterized by highly correlated waveforms (cross-correlation > 0.95), which mainly occur in the grounding zone, i.e. the region where the ice transitions from grounded ice sheet to freely floating ice shelf. The joint analysis of seismic events and observed local tidal measurements suggests that seismicity is not only triggered by a regular, periodic driver such as the ocean tides but also more likely by transient pulses. We consider potential environmental processes and their impact on the coupling between the glacier flow and the bedrock brittle failure. Among the environmental variables examined, our findings suggest that clustered and repeated seismic events may be related to transient episodes of ice-mass discharge correlated to a change in the subglacial hydrographic system that originates upstream of the glacier, lubricating the interface with the bedrock. This hypothesis is supported by the gravity variation observations provided by the GRACE satellite mission, which observed mass variations during periods characterized by seismic clustering.PublishedJCR Journa
Turbulent diffusion and volcanic gas dispersion in the atmospheric surface layer: insights from La Solfatara, Campi Flegrei, Italy
No full textNumerical models are widely used to simulate volcanic gas dispersion and estimate local emission sources. How-
ever, significant uncertainties arise from the approximations inherent in their physical formulations. Recent advances
in high-performance computing (HPC) have enabled high-resolution simulations with minimal numerical diffusion,
revealing previously unnoticed limitations in the Monin–Obukhov Similarity Theory used within atmospheric gas
dispersion models. One key issue is the determination of the minimum vertical turbulence diffusion coefficient (Kzmin)
in the atmospheric surface layer (ASL), which plays a crucial role in reducing biases in advection–diffusion models
caused by inadequate turbulence representation. In this study, we refine the Eulerian passive gas transport model
DISGAS (v. 2.5.1) using measured data on fumarolic and diffuse CO₂ fluxes and air concentrations, along with local
wind measurements collected during an ad hoc field campaign from 4 to 10 May 2023. To account for uncertainties
in gas flow rates and turbulent velocity fluctuations, we conducted a statistically robust set of simulations by varying
CO₂ fluxes and Kzmin values. Model outputs were compared with in situ CO₂ concentration measurements at fixed
monitoring stations. Results indicate that during stable atmospheric conditions, setting Kzmin within the range
of 1.5–2 m2 s−1 significantly improves agreement with observations and reduces systematic biases in source esti-
mation. These findings refine model parameterization to better represent turbulence under stable atmospheric
conditions at La Solfatara crater during the May 2023 survey. Moreover, the proposed methodology can be adopted
for automated data assimilation workflows aimed at constraining unknown fumarolic gas source fluxes in other vol-
canic settings.PublishedOSV3: Sviluppo di nuovi sistemi osservazionali e di analisi ad alta sensibilitàJCR Journa
A comprehensive integrated macroseismic dataset from multiple earthquake studies
No full textEach Italian earthquake included in the Italian Parametric Catalogue (CPTI) is based on a single study, with its database stored in the Italian Macroseismic Database (DBMI). DBMI collects macroseismic intensity data from approximately 5,000 Italian earthquakes. However, for the same events, numerous studies have been independently carried out over the years in the literature whose data have not been incorporated into the DBMI. By consolidating all available data for each event, it is possible to significantly enhance the dataset used for hazard assessments and the reconstruction of local seismic histories. This approach would make studies of individual events much more robust and comprehensive. The objective of this work is to propose the integration of different macroseismic datasets for individual events by identifying criteria that can effectively merge a large number of intensity data points. A total of 45 Italian earthquakes with data from multiple sources were identified and reassessed through a rapid review process. This effort has resulted in the creation of a new dataset, substantially increasing the number of Macroseismic Data Points (MDP) for the earthquakes covered by this study compared to those in DBMI15 (from 2,892 to 9,328 MDPs). Consequently, the macroseismic distributions for these 45 events have become more detailed, robust, and extensive.PublishedJCR Journa
The contribution of source parameter estimations and ground motion simulations in integrating input data for seismic hazard assessment: an application to the volcanic island of Ischia (Italy)
No full textOn 21 August 2017, a M w 3.9 earthquake struck the island of Ischia, causing two casualties and significant damage in the village of Casamicciola Terme and its surroundings. The earthquake was recorded by the local INGV-OV seismic network, and represents the first relevant instrumentally recorded earthquake on the island. However, it is not possible to perform a statistical analysis based on past recordings, which forms the basis of the Ground Motion Model at a local scale. The numerical simulations can help overcome this problem. Here, we first analysed the low magnitude seismicity of the island and focused on estimating the seismic attenuation and average static stress drop through spectral inversion analysis. We then used a stochastic finite-fault approach considering two source models to simulate the Casamicciola earthquake's strong ground motion by also taking into account the site effect at the IOCA station. The numerical simulations were also extended to the localities for which observed macroseismic intensity values are available. The simulated peak ground motions, converted into intensities through empirical relationships, are somewhat higher than the observed values for both source configurations, suggesting that the regional dependence between intensity and peak ground motion cannot be overlooked. Future investigations should be undertaken to improve seismic hazard assessment at a local scale. Conversely, synthetic PGAs and PGVs show a satisfactory match with the values predicted by the generic GMM calibrated for volcanic areas in Italy. The results underscore the importance of region-specific GMMs for reliable seismic scenarios.PublishedOST2 Deformazione e Hazard sismico e da maremotoJCR Journa
Combined impact of climate and seismic activity on groundwater hydrogeochemistry in the Eastern Southern Alps, Italy
No full textcharacterized by elevated Na, Cl, and temperatures, suggesting contributions from deeper sources. Stable isotopes of water and dissolved gases confirm meteoric origin for all springs, while 87 Sr/ 86 Sr, trace elements, and geothermometers further support deep inputs at Canal and Colesei. Statistical analyses (Principal Component Analysis and Change Point Detection) identified geochemical anomalies possibly linked to (i) prolonged drought, which reduced aquifer recharge and enhanced ion concentrations, and (ii) seismicity, notably a M w 5.8 earthquake ~245 km away, potentially varying mixing between shallow and deep systems. These results highlight the outstanding need for integrated monitoring to understand and manage groundwater resources, particularly in tectonically active and densely populated areas facing climate change and extreme events.PublishedJCR Journa
Tracking the November 26, 2022, Casamicciola debris flow through seismic signals (Ischia, southern Italy)
No full textThe movement of large masses on the Earth's surface, including landslides or debris flows, transfers energy to the ground, inducing both permanent and transient deformation. This generates measurable motion and seismic radiation that can be detected by proximal seismic networks. On November 26, 2022, during heavy rainfall, several debris flows inundated the northern slope of the active volcanic island of Ischia in southern Italy, causing fatalities and extensive damage. The island of Ischia is one of the most landslide-prone localities in Italy. It has already suffered comparable, even larger, events over the past two centuries, and with a population of around 60,000 and more than 300,000 tourists per year, it is considered a high natural risk zone. In this study, we performed seismological analyses over an extended range of frequencies and scales, using broadband data recorded by the local permanent seismic network, to study the dynamics of the November 26, 2022, event and to quantitatively characterise its evolution over time. Unlike post-event static surveys, a major advantage of the seismological approach is its ability to track the progression of the debris flow motion from the instant of the initial detachment. Our analyses allowed us to estimate the spatial and temporal origin of the rock detachments, the mass of the flowing material, the size of the coarse boulders, the speed at which the landslide approached the nearest seismic station, and the impacting overpressure that caused the most severe damage. These results further demonstrate that specifically designed instrumental (seismic and tiltmetric) networks represent an essential tool for real-time monitoring and for activating early warning systems prior to potential damage to inhabited localities.PublishedJCR Journa