ALBERT

Description: Active normal faulting and uplifting, consistent with a WNW-ESE-oriented regional extension, dominate the Quaternary tectonics of the southern Calabrian Arc. The main tectonic structures of this extensional domain are considered to be the source of numerous historical and recent strong earthquakes, among which the 1783 seismic sequence (M 6.5–7) was one of the most destructive earthquakes ever recorded in Southern Italy. Previous works on the seismotectonic of the Calabrian Arc indicate a disagreement on the attitude (E-dipping vs W-dipping) of the main seismogenic sources slicing across southern Calabria, whereby the seismotectonic framework is still debated. Following a multidisciplinary approach, based on morpho-structural and seismological data, the geometry at depth of the most reliable sources (i.e., Cittanova and Serre faults) was first modelled in a 3D environment to retrieve information about their seismic potential. The GNSS data from the permanent stations of RING/RDN and TopNETlive Italy networks have been processed in order to estimate the velocity field affecting this area. Then, data inversion allowed us to document a predominant WNW-ESE active extensional strain orthogonally to the modelled faults, consistent with the regional dynamics. The reliability of the model was tested using empirical relationships and fault response modelling simulation. Furthermore, slip tendency analysis revealed the propensity to slip of the modelled planes by applying a remote stress state derived from the kinematic-structural survey on fault planes.

Description: PRIN 2017, under grant number “2017KT2MKE” PIAno di inCEntivi per la RIcerca di Ateneo (PIACERI 2020/2022)

Description: Published

Description: 1240051

Description: OST3 Vicino alla faglia

Description: JCR Journal

Description: Reply to the comment by Luca Bolognesi

Description: Reply to the comment by Luca Bolognesi

Description: Published

Description: 102754

Description: OSA5: Energia e georisorse

Description: JCR Journal

Description: The natural park of Le Biancane is located in the southern sector of the Larderello-Travale geothermal field (LTGF). It extends over an approximately 100,000 m2 area where the impermeable caprock is locally absent and deep fluids may directly reach the surface. Through a multidisciplinary approach including measurements of soil CO2 flux (total output of 11.5 t day􀀀 1), soil temperature (average 34.4 ◦C), stable isotope and chemical data on fluids from fumaroles (dominated by a mixture of geothermal gases and air or gases from air-saturated meteoric water), and structural analysis of the formation outcropping, we found that anomalous CO2 emissions are positively correlated with shallow temperature anomalies. These are in restricted locations adjacent to vents and fumaroles, where a network of well-connected fractures (preferentially NW-SE and NE-SW orientated and with steep dips) drains efficiently allowing upward migration of the deep fluids and the energy toward the surface.

Description: INGV Project RL 2021 - AGEREMUS

Description: Published

Description: 102616

Description: OSA5: Energia e georisorse

Description: JCR Journal

Description: The late Miocene Monte Capanne and Porto Azzurro plutons are investigated by means of coupled U-Pb zircon and 40Ar/39Ar white mica dating to test the occurrence of long-lived magmatic systems in the upper crust. Zircon crystallized for 〉 1 Myr in both plutonic systems, with supersolidus conditions overlapping for ~220 kyr indicating previously unrecognized co-existence of the two reservoirs. The development of the Porto Azzurro high T-aureole is post-dated by continuous igneous zircon crystallization until ~ 6.0 Ma. By linking crystallization to post-emplacement cooling of late-stage pulses in both western and eastern Elba we constrain long-lived sizeable reservoirs (possibly the same reservoir) in the Tyrrhenian upper crust between ~8 and 6 Ma.

Description: In press

Description: OST1 Alla ricerca dei Motori Geodinamici

Description: JCR Journal

Description: La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 settembre al 31 dicembre 2022 ha riguardato tutti i terremoti di magnitudo M≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (M≥3.5) e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag-6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: OST5 Verso un nuovo Monitoraggio

Description: La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 gennaio al 30 aprile 2023 ha riguardato tutti i terremoti di magnitudo M≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (M≥3.5) e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag- 6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: OST5 Verso un nuovo Monitoraggio

Description: In this body of work, we showcase a historic virtual geotrail on the eastern flank of the iconic Mt. Etna volcano (Italy), along a series of outstanding geological sites and features subsequent to an important eruption that took place in 1928. A geohistoric account of such a major eruption, is of great interest, since it is the only event since 1669 to have caused the destruction of a town (Mascali) in the Etna region. Volcanologists, educators, the lay public, tourists and volcano explorers can now access a series of “virtual geostops” belonging to this virtual geotrail, such that “visitors” can virtually fly above these sites by scanning a QR code on the printed or electronic version of the present manuscript, as well as on the poster provided as additional material for this manuscript. The virtual geostops that comprise the virtual geotrail were developed using the structure-frommotion (SfM) photogrammetry technique from images captured by using unmanned aerial vehicles (UAVs). The main result of our work is the virtual geotrail, subdivided in two parts and composed of eight geostops, each showing outstanding examples of geological features resulting from volcanic phenomena that took place also during 1979. Our approach is designed to support classical field trips, and it can undoubtedly become complementary to traditional field teaching in earth sciences, both now and in the future.

Description: Published

Description: 377

Description: 1V. Storia eruttiva

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: 2TM. Divulgazione Scientifica

Description: JCR Journal

Description: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Description: Unpublished

Description: 4T. Sismicità dell'Italia

Description: Fault zone architecture and its internal structural variability play a pivotal role in earthquake mechanics, by controlling, for instance, the nucleation, propagation and arrest of individual seismic ruptures and the evolution in space and time of foreshock and aftershock seismic sequences. Nevertheless, the along-strike architectural variability of crustal-scale seismogenic sources over regional distances is still poorly investigated. Here, we describe the architectural variability of the 〉40-km-long exhumed, seismogenic Bolfin Fault Zone (BFZ) of the intra-arc Atacama Fault System (Northern Chile). The BFZ cuts through plutonic rocks of the Mesozoic Coastal Cordillera and was seismically active at 5–7 km depth and ≤ 300 °C in a fluid-rich environment. The BFZ includes multiple altered fault core strands, consisting of chlorite-rich cataclasites-ultracataclasites and pseudotachylytes, surrounded by chlorite-rich protobreccias to protocataclasites over a zone up to 60-m-thick. These fault rocks are embedded within a low-strain damage zone, up to 150-m-thick, which includes strongly altered volumes of dilatational hydrothermal breccias and clusters of epidote-rich fault-vein networks at the linkage of the BFZ with subsidiary faults. The strong hydrothermal alteration of rocks along both the fault core and the damage zone attests to an extensive percolation of fluids across all the elements of the structural network during the activity of the entire fault zone. In particular, we interpret the epidote-rich fault-vein networks and associated breccias as an exhumed example of upper-crustal fluid-driven earthquake swarms, similar to the presently active intra-arc Liquiñe-Ofqui Fault System (Southern Andean Volcanic Zone, Chile).

Description: European Research Council Consolidator Grant Project (NOFEAR) No 614705

Description: Published

Description: 104745

Description: 3T. Fisica dei terremoti e Sorgente Sismica

Description: JCR Journal

Description: In the last two decades, the rapid growth in continuous Global Navigation Satellite Systems (GNSS) networks and improvements in Interferometric Synthetic Aperture Radar (InSAR) imaging allowed the acquisition of continuous and spatially extensive datasets over large regions of Earth, significantly increasing the range of geoscience applications. In addition, the promising results obtained by the scientific community and the free availability of data, which permitted drastic cost reductions, have drawn increasing interest from the administrative managing office for the mapping and monitoring of ground deformation issues. This Special Issue aims to provide a general overview of some geoscience applications of GNSS and InSAR techniques which are commonly used to study the surface deformation related to co- and post-seismic deformation, subsurface movements of magma beneath active volcanoes, soil deformation (e.g., natural/anthropic uplift or subsidence), monitoring of landslide, monitoring of industrial settlements, the motion of ice sheets, etc. The GNSS technique provides a set of 3D geodetic observations at a limited number of points on the ground surface. The continuous technological development in GNSS equipment currently allows collecting measurements at higher rates (up to 100 Hz), offering a wide range of new applications for solid and fluid Earth investigations. The InSAR technique provides a spatially dense set of geodetic observations of ground deformation in the viewing geometry of the satellite sensor, and with a temporal sampling limited to the satellite orbital revisit (up to 6 days with the Sentinel constellations). Any deformation of the ground surface can be measured by comparing two radar images of the same area, collected at different times from approximately the same position in space. InSAR processing advancements also allowed multi-temporal analyses, which sensibly improved the investigation of long-term deformation events. GNSS and InSAR measurements can complement each other and are generally combined to infer the 3D surface deformation over a target region. A review of more than 190 studies dealing with InSAR and GNSS combined measurements has been proposed in Del Soldato et al. [1]. The ground deformation measurements coming from both techniques have been combined for different purposes [1], evidencing how their joint use has been readily employed by the scientific community as well as by stakeholders and environmental managers. In turn, the increasing range of applications started to push the development of new approaches aimed at fast and robust combinations of GNSS and InSAR measurements. In such a frame, Xiong et al. [2] proposed an iterative least squares approach for virtual observation (VOILS) based on the maximum a posteriori estimation criterion of Bayesian theorem while Parizzi et al. [3] developed an approach accounting for the spectral properties of the errors of InSAR and GNSS measurements, hence preserving all spatial frequencies of the deformation detected by the two techniques. Both methods have been tested and validated with both synthetic and real data. Achieved results highlighted that both methods led to significant improvement of the spatial accuracy of the combined deformation field, therefore allowing accurate detection of the ongoing deformations. Several studies included in this Special Issue focused on the co-seismic deformation related to moderate to large earthquakes. De Novellis et al. [4] focused on the March 2021 Thessaly seismic sequence (Central Greece) highlighting the activation of unknown distinct blind fault segments in a sort of domino effect within the seismogenic crustal volume. Caporali et al. [5] analyzed the seismic sequence of November 2019 in Albania and inferred a NE-dipping reverse seismogenic fault located at a depth of 8 ± 2 km. Sakkas [6] focused on the 30 October 2020 Mw6.9 Samos Island (Aegean Sea) earthquake and suggested that the earthquake nucleated on a two-segments north-dipping listric fault characterized by a predominant dip-slip component and a minor lateral one. The complex deformation field associated with the April 2016 Kumamoto (Japan) seismic sequence was analyzed by He et al. [7] which modelled a four-segment fault geometry with right-lateral strike-slip kinematics coupled with a minor normal slip component. Valerio et al. [8] focused on the 7 November 2019 Mw5.9 earthquake hitting the East-Azerbaijan region and proposed a shallow NE-SW striking and SE-dipping fault as the seismogenic source. All these studies clearly proved that GNSS and InSAR data analysis and modelling are extremely useful tools in helping to constrain the causative fault of moderate to large earthquakes, especially in the case of blind and unknown faults, therefore providing useful information on the seismic hazard estimation of the investigated areas. Active faults can be also affected by long-term creeping during the interseismic period. Geodetic observations are used to investigate co- and post-seismic deformations as well as transient deformations at least when these phenomena yield deformations high enough to be discriminated from long-term trends. However, there could be the possibility that the whole amount of observed long-term deformation could be partially or totally caused by inelastic processes instead of related to the building of elastic stress preparing the next earthquakes. Cambiotti et al. [9] focused on this topic by proposing a novel inverse method aimed at the discrimination of regional deformation and of long-term fault creep by inverting available GNSS measurements. Sparacino et al. [10] performed a seismic and geodetic moment-rates comparison for the western Mediterranean to identify that regions where the total deformation-rate budget is entirely released by crustal seismicity, and the ones where the excess deformation-rate can be released either in aseismic slip across active faults or through large future earthquakes. Achieved results by both studies proven that the geodetic measurements represent an essential part of the seismic-hazard analysis on highly deforming regions. Other studies included in this Special Issue focused on the surface deformation related to the migration of fluids along the magmatic system of active volcanoes. Galvani et al. [11] analyzed twenty years of GNSS and levelling measurements collected on Ischia Island (Italy) and found a deflating source located at a depth of 4 km below the southern flank of Mt. Epomeo. Battaglia et al. [12] studied the subsidence of Dallol volcano (Erta Ale ridge of Afar, Ethiopia) and inferred a deflating source located beneath the volcano edifice at a depth ranging in the 0.5–1.5 km interval and characterized by a volume decrease between −0.63 and −0.26 × 106 km3/year. Boixart et al. [13] focused on the Sabancaya volcano (southern Perú), detecting an active deep source of deformation located between the Sabancaya and Hualca volcanoes with a volume change rate of 26 × 106–46 × 106 m3/yr. These studies evidenced that GNSS and InSAR techniques can detect and track with high detail the spatial and temporal evolution of the magmatic system during a volcanic crisis. Both techniques are essential tools for the continuous monitoring of active volcanoes as well as to understand magmatism, refine volcano models, and mitigate volcanic hazards. Another topic addressed in this Special Issue is that of land subsidence which can occur for both natural and anthropic causes. Land subsidence represents a relevant issue that might affect highly developed urban and industrialized areas. Cando Jácome et al. [14] focused on the land subsidence due to the underground mining which is causing the collapse of many buildings in the urban area of Zaruma in Ecuador. The authors proposed a forecasting methodology for the continuous monitoring of the long-term soil subsidence in target areas, largely improving the traditional detection performed with total stations and geodetic marks. Mohamadi et al. [15] designed a PS-InSAR-based workflow on the detection of unusual vertical surface motions in urban areas in order to create temporal vulnerability maps for building collapse monitoring. Both studies highlight that the development of methodologies for the continuous monitoring of the land subsidence is strictly required to improve security standards aimed at the building collapse risk reduction in densely urbanized areas.

Description: Published

Description: 1104

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Seismic coupling helps define how large the earthquake potential of a region is, as well as the presence of asperities along plate zones. This work seeks to provide an improved picture of the seismic coupling for the Aegean-Anatolian region by taking advantage of extensive seismic and geodetic datasets. To estimate coupling, we compiled a series of by-products that are specific ingredients also for seismic hazard studies. With these by-products, we found that the seismogenic thickness is thinner (10–15 km) or thicker (20 to 30 km) to the east and to the west, respectively and even deeper along the Hellenic subduction zone. The b-value ranges between 0.9 and 1.1 for the entire area with high values concentrated at locations of Late Miocene to -recent volcanism whereas low b-values (〈0.8) concentrate along most of the Northern Anatolian fault zone that may suggests stress accumulation. Seismic coupling is low (〈35%) or intermediate (35% - 70%) in most of the area, while the Karliova triple junction, on a N-S-oriented belt along the boundary between western and central Anatolia, and the southeastern Peloponnese are fully coupled, suggesting a full seismic release of the entire deformation budget. An intermediate value of seismic coupling is observed for the eastern and central segments of the Northern and Eastern Anatolian Fault zones, for part of the Hellenic volcanic arc, the Kefalonia Transform Fault and the Corinth gulf active faults. Considering historical earthquake data, these intermediate coupling values indicate either aseismic deformation or catalog incompleteness. Furthermore, the time period since large magnitude earthquakes clearly raises the possibility of impending earthquakes on the Northern and Eastern Anatolian Fault zones. A broad seismic gap is evidenced along the Hellenic subduction zone, because of the reduced coupling and the absence of ~M8 earthquakes in the last 700 years, at least. We conclude that in most of the central Aegean Sea aseismic deformation prevails as suggested by the small value of coupling and the modest seismic release over the last millennium.

Description: Published

Description: 103993

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Minimum 1D velocity models and station corrections have been computed for the central Mediterranean area using two main data sets. The first one consists of accurate first arrival‐time readings from 103 seismic events with magnitude (ML)≥3.5 recorded by the Italian National Seismic Network (RSN) and the AlpArray Seismic Network (AASN) in the period 2014–2021. Earthquakes were selected on the basis of their spatial distribution, epicentral distance to the nearest seismic station, and maximum distance traveled by Pn and Sn phases. This fine selection of high‐quality data combined with the spatial density of the AlpArray seismic stations was decisive in obtaining high resolution for upper mantle velocity, especially in the Alpine belt. To obtain a denser coverage of crustal rays, we extended the first data set with P and S arrivals of local earthquakes from Istituto Nazionale di Geofisica e Vulcanologia (INGV) bulletin data (2016–2018). A total of 75,807 seismic phases (47,183 P phases and 28,264 S phases) have been inverted to calculate best‐fit 1D velocity models, at regional and local scales. We then test the performance of the optimized velocity models by relocating the last four years of seismicity recorded by INGV (period 2017–2020). The computed velocity models are very effective for routine earthquake location, seismic monitoring, source parameter modeling, and future 3D seismic tomography.

Description: Published

Description: 2670--2685

Description: 4T. Sismicità dell'Italia

Description: JCR Journal

Description: The exploitation of a geothermal field can be accompanied by both natural and induced seismicity. Hence the installation of a seismic network suitable for locating also low magnitude earthquakes is of great interest for geothermal development, especially for monitoring the activity related to the injection or production. Here we propose an improvement of the D-OPTIMAL algorithm (Tramelli et al., 2013) that tries and find optimal station positions minimizing the volume of the error ellipsoid of the event location using the D-criterion. In this version, we introduced the possibility to account for several prior information that is generally available when instrumenting a monitoring site permanently or temporarily. The a priori parameters introduced are: i) three-dimensional seismic velocity models, ii) seismic noise levels, iii) topographic gradient, and iv) H/V ratio values. The last three parameters are introduced in the station position 24 selection using aweighting system. We applied the methodology to the Acoculco geothermal field (Mexico) where an injection test was planned and executed in 2021. The comparison between the network defined usingthe standard approach and this updated version shows the importance of introducing a prioriinformation during the selection of the network. Installation sites resulted better distributed on the region, resulting in an overall increase of the sensitivity, and in a decreasing of the error location estimation in the target region. The methodology presented here is easy to apply to other study cases such as active volcanoes, anthropogenic activities, or whatever other study at local scale.

Description: Published

Description: 103995

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 maggio al 31 agosto 2022 ha riguardato tutti i terremoti di magnitudo ML≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (ML≥3.5), e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag- 6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impatto

Description: La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 gennaio al 30 aprile 2022 ha riguardato tutti i terremoti di magnitudo ML≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (ML≥3.5), e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag- 6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impatto

Description: Duvalo “volcano” is a site of anomalous geogenic degassing close to Ohrid (North Macedonia) not related to volcanic activity, despite its name. CO2 flux measurements made with the accumulation chamber (321 sites over ∼50,000 m2) showed fluxes up to nearly 60,000 g m−2 d−1, sustaining a total output of ∼67 t d−1. Soil gas samples were taken at 50 cm depth from sites with high CO2 fluxes and analyzed for their chemical and isotope composition. The gas is mainly composed by CO2 (〉90%) with significant concentrations of H2S (up to 0.55%) and CH4 (up to 0.32%). The isotope compositions of He (R/RA 0.10) and of CO2 (δ13C ∼ 0‰) exclude significant mantle contribution, while δ13C-CH4 (∼−35‰) and δ2H-CH4 (∼−170‰) suggest a thermogenic origin for CH4. The area is characterized by intense seismic activity and Duvalo corresponds to an active tectonic structure bordering the Ohrid graben. The production of H2S within the stratigraphic sequence may be explained by thermochemical reduction of sulfate. The uprising H2S is partially oxidized to sulfuric acid that, reacting with carbonate rocks, releases CO2. The tectonic structure of the area favors fluid circulation, sustaining H2S production and oxidation, CO2 production and allowing the escape of the gases to the atmosphere. In the end, Duvalo represents a tectonic-related CO2 degassing area whose gases originate mostly, if not exclusively, in the shallowest part of the crust (〈10 km). This finding highlights that even systems with trivial mantle contribution may sustain intense CO2 degassing (〉1,000 t km−2 d−1).

Description: Published

Description: e2021GC010198

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: We carried out new geological, morphotectonic, geophysical and paleoseismological investigations on the Meduno Thrust that belongs to the Pliocene-Quaternary front of the eastern Southern Alps in Friuli (NE Italy). The study area is located in the Carnic Prealps, where a series of alluvial terraces, linked to both climatic and tectonic pulses characterises the lower reach of the Meduna Valley. In correspondence of the oblique ramp of the Meduno Thrust, the Late Pleistocene Rivalunga terrace shows a set of scarps perpendicular to the Meduno valley, often modified by human activity. In order to reconstruct the tectonic setting of the area and identify the location for digging paleoseismological trenches, integrated geophysical investigations including electrical resistivity tomography, seismic refraction and reflection, ground penetrating radar and surface wave analyses (HVSR, ReMi and MASW), were carried out across the scarps of the Rivalunga terrace. Geophysical surveys pinpointed that in correspondence of the oblique ramp, stress is accommodated by a transpressive thrust system involving all the seismo-stratigraphic horizons apart from the ploughed soil. Trenching illustrated the Meduno Thrust movements during Late Pleistocene-Holocene. Trenches exhibited both shear planes and extrados fracturing, showing deformed alluvial and colluvial units. 14C datings of the colluvial units show that the most recent fault movements occurred after 1360 CE and 1670 CE. The age of the deformed stratigraphic units compared with the earthquakes listed in current catalogues, suggests that the 1776 earthquake (Mw 5.8, Io = 8–9 MCS) could represent the last seismic event linked to the Meduno thrust activity. This study provided new quantitative constraints improving seismic hazard assessment for Carnic prealpine area.

Description: The research developed in the framework of the agreement between the Regione Autonoma Friuli Venezia Giulia - Direzione Centrale Ambiente ed Energia - Servizio Geologico, the Istituto Superiore per la Protezione e la Ricerca Ambientale (I.S.P.R.A.) and the University of Udine. The project was funded by the Regione Autonoma Friuli Venezia Giulia, Direzione Centrale Ambiente ed Energia, Servizio Geologico (C.I. G.: Z0E0C5EF75, p.i. Maria Eliana Poli).

Description: Published

Description: 229071

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Mts. Simbruini karst aquifer feeds important springs whose capture contributes to the water supply of Rome City. To improve the geochemical characterization of this aquifer, we analyzed 36 groundwater samples, 29 from springs and 7 from shallow wells, collected in 1996 and 2019. Atomic adsorption spectroscopy, titration, ionic chromatography and mass spectrometry were the used analytical methods. Groundwater is bicarbonate alkaline-earth type and HCO3- dominance confirms that the aquifer is hosted in carbonate rocks. Total alkalinity vs. cations plot indicates that CO2 driven weathering controls the water chemistry. The probability plots of HCO3-, cations and Ca2+ +Mg2+ indicate four groundwater populations with the less represented one (9 samples)characterized by the highest PCO2 values (〉 0.3 atm). Most anomalous values of the dissolved PCO2are from springs located near the center of the studied area. Four samples have negative values of𝛿13CCO2 (about -22‰ vs. PDB), indicating its organic origin, but two other samples have positivevalues (1.6 and 2.6 ‰ vs. PDB), similar to those observed in the CO2 of deep origin discharged atthe close Colli Albani volcano. Therefore, geochemical evidence indicates that the Mts. Simbruiniaquifer is locally affected by the input of deep originated CO2, likely rising up along fractures, interacting with a recharge of meteoric origin, as evidenced by its 𝛿2H and 𝛿18O isotopic signatures.

Description: Published

Description: HS659

Description: 1TR. Georisorse

Description: JCR Journal

Description: Extensive geophysical and geodetic measurements were carried out to evaluate the groundwater aquifer, trace the basement relief, as well as detect the igneous intrusions and structural elements (mainly faults) that affect the occurrence of groundwater in the study area. The fieldwork included resistivity sounding, a geomagnetic survey, and Global Positioning System measurements. The magnetic results showed the presence of a group of main faults in East-west trend at the western part of the area and major fault at the northern part of the area of NW-SW trend. The findings also showed the presence of two igneous rock intrusions located in the middle of the eastern part of the valley. Pronounced differences in the depths of basement rocks have been identified, ranging between 0 and 900 m from the surface. Both high horizontal movements and high shear strain rates have been found to be concentrated at the southeast of the study area and it was noted that high stress was accumulated along the main observed faults and at the main groundwater aquifers. The geoelectrical results confirmed the presence of two aquifers; a shallow aquifer (Quaternary aquifer) that narrows northwards and a Nubian sandstone aquifer, which considered the main aquifer. The Nubian sandstone aquifer carries groundwater in the region, which overlies the last geoelectric unit represented by the basement complex layer and geological structures affecting the potential availability of groundwater in the study area, as proved by the geomagnetic survey and stress accumulation.

Description: Researchers Supporting Project number (RSP-2021/351), King Saud University, Riyadh, Saudi Arabia

Description: Published

Description: 101549

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: The assessment of potential radon-hazardous environments is nowadays a critical issue in planning, monitoring, and developing appropriate mitigation strategies. Although some geological structures (e.g., fault systems) and other geological factors (e.g., radionuclide content, soil organic or rock weathering) can locally affect the radon occurrence, at the basis of a good implementation of radon-safe systems, optimized modelling at territorial scale is required. The use of spatial regression models, adequately combining different types of predictors, represents an invaluable tool to identify the relationships between radon and its controlling factors as well as to construct Geogenic Radon Potential (GRP) maps of an area. In this work, two GRP maps were developed based on field measurements of soil gas radon and thoron concentrations and gamma spectrometry of soil and rock samples of the Euganean Hills (northern Italy) district. A predictive model of radon concentration in soil gas was reconstructed taking into account the relationships among the soil gas radon and seven predictors: terrestrial gamma dose radiation (TGDR), thoron (220Rn), fault density (FD), soil permeability (PERM), digital terrain model (SLOPE), moisture index (TMI), heat load index (HLI). These predictors allowed to elaborate local spatial models by using the Empirical Bayesian Regression Kriging (EBRK) in order to find the best combination and define the GRP of the Euganean Hills area. A second GRP map based on the Neznal approach (GRPNEZ) has been modelled using the TGDR and 220Rn, as predictors of radon concentration, and FD as predictor of soil permeability. Then, the two GRP maps have been compared. Results highlight that the radon potential is mainly driven by the bedrock type but the presence of fault systems and topographic features play a key role in radon migration in the subsoil and its exhalation at the soil/atmosphere boundary.

Description: Published

Description: 152064

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 maggio al 31 agosto 2021 ha riguardato tutti i terremoti di magnitudo ML≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (ML≥3.5) e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag-6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: 4IT. Banche dati

Description: La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 settembre al 31 dicembre 2021 ha riguardato tutti i terremoti di magnitudo ML≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (ML≥3.5) e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag- 6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: 4IT. Banche dati

Description: Intermediate depth (70-300 km) and deep (〉300 km) earthquakes have always been puzzling Earth scientists: their occurrence is a paradox, since the ductile behavior of rocks and the high confining pressure with increasing depths would theoretically preclude brittle failure and frictional sliding. The mechanisms proposed to explain deep earthquakes, mainly depending on the subducting plate age and stress state, are generally expressed by single parameters, unsuitable to comprehensively account for differences among distinct subduction zones or within the same slab. We analyze the Kurile and Izu-Bonin intraslab seismicity and detail the stress state along the subducted planes using the Gutenberg-Richter b-value. We demonstrate that, despite the slabs different properties (e.g., lithospheric age, stress state, dehydration rate), in both cases deep earthquakes are restricted to depths characterized by equal age from subduction initiation and are driven by stress regimes affected by the persistence of the metastable olivine wedge.

Description: Published

Description: 12440

Description: 3T. Fisica dei terremoti e Sorgente Sismica

Description: JCR Journal

Description: Miscellanea INGV - Progetto “Sale Operative Integrate e Reti di monitoraggio del futuro: l’INGV 2.0”. Report finale

Description: L’INGV è Centro di Competenza per i fenomeni sismici, vulcanici e i maremoti per il Dipartimento di Protezione Civile Nazionale (DPC). Nell’ambito delle attività previste dall’Accordo Quadro DPCINGV 20122021 (AQ vigente), l’INGV svolge attività di sorveglianza tecnicoscientifica sulla sismicità del territorio nazionale, sui fenomeni vulcanici e sui maremoti, finalizzata ai compiti di protezione civile, in modo ininterrotto (H24 per 365 giorni l’anno). Tale attività viene realizzata con uno specifico assetto organizzativo, che consente la trasmissione in tempo reale verso il DPC di tutte le informazioni riguardanti eventi e rischi sismici, vulcanici e da maremoto di interesse per il Dipartimento stesso. La sorveglianza sismica del territorio nazionale e delle aree limitrofe è in carico all’Osservatorio Nazionale Terremoti (ONT), insieme alle comunicazioni relative agli eventi in area mediterranea e nel mondo. La sorveglianza delle aree vulcaniche campane (Campi Flegrei, Ischia, Vesuvio) e siciliane (Etna, Stromboli, Vulcano, altre isole Eolie, Pantelleria) sono rispettivamente in carico all’Osservatorio Vesuviano (OV) e all’Osservatorio Etneo (OE). Dal gennaio 2017 è diventata ufficialmente operativa anche l’attività di monitoraggio e il Servizio di allerta dei maremoti di origine sismica (Centro Allerta Tsunami CAT) con l’introduzione nella Sala INGV di Roma di una nuova unità di personale. In fase sperimentale, fino alla fine del 2016, e per i primi mesi di operatività, il personale per il Servizio di Allerta Tsunami è stato scelto all’interno del gruppo di turnisti che da anni svolgeva il Servizio di Sorveglianza Sismica; successivamente, è stato reclutato e formato nuovo personale in grado di svolgere entrambi i Servizi. A partire dal 2017 e nei due anni successivi sono stati attivati, quindi, i corsi per la formazione di nuovi Turnisti e Funzionari per i servizi di Sorveglianza Sismica e di Allerta Tsunami ed anche per i reperibili di Sala [Quintiliani et al., 2020]. La formazione del personale che partecipa al Servizio di Sorveglianza Sismica è prevista nei Piani di attività annuali relativi all’Allegato A dell’AQ vigente, tematica “Sorveglianza sismica” e quella del personale che partecipa alle attività del CAT nella tematica “Centro Allerta Tsunami (CAT)”. Inoltre, il Progetto “S.O.I.R. monitoraggio futuro” ha tra le sue finalità quella della formazione del personale delle Sale Operative INGV, essendo il WP4 “Formazione” uno dei sei working package del progetto espressamente dedicato a questo.

Description: Published

Description: 150-155

Description: 1SR TERREMOTI - Sorveglianza Sismica e Allerta Tsunami

Description: N/A or not JCR

Description: The Earth is a dynamic planet, where earthquakes and volcanoes are among some of its most outstanding expressions. Just like our planet as a whole is subject to lunisolar gravitational tides, seismic and volcanic activity are also influenced by the relative motion of the Sun and Moon. This tidal influence takes different forms, spanning different spatial and temporal scales, from quasiperiodic patterns with semidiurnal to multiannual periods to the triggering of earthquakes and volcanic eruptions. Tidal stresses have been primarily evoked as driving forces, although they are 3–5 orders of magnitude smaller than tectonic stresses, which makes cause-effect relationships elusive. This chapter reviews the different observations of tidal influence in geophysical and geochemical data acquired in tectonic and volcanic settings, as well as the methods that have been developed to detect it. Using case studies, we provide some insights on the sensitivity of geological systems to tidal stresses.

Description: Published

Description: 333-364

Description: 4V. Processi pre-eruttivi

Description: The 24–27 December 2018 flank eruption at Mount Etna (Southern Italy) has been investigated through a multidisciplinary approach in which olivine chemical zoning and diffusion chronometry data were integrated with models inferred by GNSS (Global Navigation Satellite System) measurements. Inspection of the olivine chemical zoning from core to rim allowed the identification of some dominant ways of transfer and interaction between magmas pertaining to different magmatic environments. Most of crystal cores are representative of crystallization at pressure of 290–230 and 160–120 MPa. Olivine rims suggest re‐equilibration at shallow pressure (≤30 MPa). Geodetic‐based models indicate pressurization of near‐vertical prolate spheroidal sources centered at ∼7.2 km below sea level (bsl) between 9 June 2017 and 28 June 2018 and later at ∼5.1 km bsl between 28 June 2018 and the eruption onset. Geodetic data also highlight a change in the inflation rate since late June 2018 and later around November 2018, which has been here related to both replenishment phases and magma uprising across the plumbing system. Timescales of magma replenishment are in agreement with prolonged recharge from deep levels upward to shallow environments started about 6 months before the eruption, with further replenishment involving the upper magmatic environments just 3–16 days before the eruption. At present, the eruptive activity at the volcano is primarily controlled by pressure imbalances affecting extensive sections of the plumbing system, with possibility to develop persistent eruptive activity at the summit versus flank eruptions depending on fortuitous interruptions of the steady magma recharge/discharge rate at shallow levels.

Description: Università di Catania (University of Catania). Grant Numbers: Three Year Plan 2016‐18 project code 22722132140, Three Year Plan 2020‐22 project code 22722132140

Description: Published

Description: e2020GC009226

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: La Palma is one of the youngest of the Canary Islands, and historically the most active. The recent activity and unrest in the archipelago, the moderate seismicity observed in 2017 and 2018 and the possibility of catastrophic landslides related to the Cumbre Vieja volcano have made it strongly advisable to ensure a realistic knowledge of the background surface deformation on the island. This will then allow any anomalous deformation related to potential volcanic unrest on the island to be detected by monitoring the surface deformation. We describe here the observation results obtained during the 2006–2010 period using geodetic techniques such as Global Navigation Satellite System (GNSS), Advanced Differential Synthetic Aperture Radar Interferometry (A-DInSAR) and microgravimetry. These results show that, although there are no significant associated variations in gravity, there is a clear surface deformation that is spatially and temporally variable. Our results are discussed from the point of view of the unrest and its implications for the definition of an operational geodetic monitoring system for the island

Description: This research was mainly funded by the Spanish Ministerio de Ciencia, Innovación y Universidades research project DEEP-MAPS, grant agreement number RTI2018-093874-B-I00. It was also partially supported by the CSIC project 201530E019 and the project GEOSIR, grant agreement AYA2010-17448 from the Spanish Ministerio de Ciencia e Innovación.

Description: Published

Description: 2566

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: Nel periodo che va dal 1 gennaio al 30 aprile 2020, gli analisti del BSI hanno effettuato la revisione di tutti gli eventi di magnitudo M≥1.5, registrati dalle stazioni sismiche dell’INGV. I terremoti di magnitudo inferiore a tale soglia di revisione vengono localizzati in tempo reale, nella sala di sorveglianza sismica di Roma. I terremoti di M≥3.5, e pochi altri di particolare interesse (vedi Marchetti et al., 2016, DOI: 10.4401/ag-7169), vengono revisionati dagli analisti del BSI, contestualmente al loro accadimento.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: 4IT. Banche dati

Description: The recent signs of reawakening at Campi Flegrei caldera (Southern Italy) received a great deal of attention due to the issues related to the volcanic risk management in a densely populated area. This paper explores relations between ground deformations, seismicity and geochemical time series in the time span 2004–2016. The aim is to unravel primary processes of unrest and the related indicators which may change in time. Data structure and interactions among variables were examined applying the clustering analysis, the correlations and the Granger causality test. The hierarchical agglomerative clustering detected two sub-periods which were further investigated. In both sub-period causal links were observed between variables while correlations did not appear and vice versa. Thus, well established formal approaches are required to study causal relations. Granger test results indicate that during 2004–2011 the awakening unrest could be mainly ascribed to hydrothermal system pressure fluctuations, probably induced by deep-rooted fluids injection, and that ground deformation together with CO2/H2O appears the most suitable geo-indicators. The 2011–2016 sub-period is characterized by enhanced dynamical connectivity. Granger test results suggest that the unrest is driven by a more localized and shallower thermohydromechanical engine. CO/CO2, He/CH4 and ground deformation velocity are mutually interacting appearing the most suitable geo-indicators.

Description: INGV Project PRIN n. 20174 × 3P29 FLUIDS

Description: Published

Description: 185

Description: 5V. Processi eruttivi e post-eruttivi

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: https://www.sciencedirect.com/science/article/abs/pii/S0012821X20303897

Description: Published

Description: 116445

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: We present a novel inverse method for discriminating regional deformation and long-term fault creep by inversion of GNSS velocities observed at the spatial scale of intraplate faults by exploiting the different spatial signatures of these two mechanisms. In doing so our method provides a refined estimate of the upper bound of the strain accumulation process. As case study, we apply this method to a six year GNSS campaign (2003–2008) set up in the southern portion of the Pollino Range over the Castrovillari and Pollino faults. We show that regional deformation alone cannot explain the observed deformation pattern and implies high geodetic strain rate, with a WSW-ENE extension of 86±41×10−9/yr. Allowing for the possibility of fault creep, the modelling of GNSS velocities is consistent with their uncertainties and they are mainly explained by a shallow creep over the Pollino fault, with a normal/strike-slip mechanism up to 5 mm/yr. The regional strain rate decrease by about 70 percent and is characterized by WNW-ESE extension of 24±28×10−9/yr. The large uncertainties affecting our estimate of regional strain rate do not allow infering whether the tectonic regime of the area is extensional or strike-slip, although the latter is slightly more likely

Description: Published

Description: 2921

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Based on multidisciplinary data, including seismological and geodetic observations, as well as seismic reflection profiles and gravity maps, we analysed the pattern of crustal deformation and active tectonics in the Sicily Channel, a key observation point to unravel the complex interaction between two major plates, Nubia and Eurasia, in the Mediterranean Sea. Our data highlight the presence of an active ~ 220-km-long complex lithospheric fault system (here named the Lampedusa-Sciacca Shear Zone), approximately oriented N-S, crossing the study area with left-lateral strike-slip deformations, active volcanism and high heat flow. We suggest that this shear zone represents the most active tectonic domain in the area, while the NW-SE elongated rifting pattern, considered the first order tectonic feature, appears currently inactive and sealed by undeformed recent (Lower Pleistocene?) deposits. Estimates of seismological and geodetic moment-rates, 6.58 × 1015 Nm/year and 7.24 × 1017 Nm/year, respectively, suggests that seismicity accounts only for ~ 0.9% of crustal deformation, while the anomalous thermal state and the low thickness of the crust would significantly inhibit frictional sliding in favour of creeping and aseismic deformation. We therefore conclude that a significant amount of the estimated crustal deformation-rate occurs aseismically, opening new scenarios for seismic risk assessments in the region.

Description: Published

Description: 21238

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Reply to Argnani, A. (2020). Comment on“Geometry of the deep Calabriansubduction (Central MediterraneanSea) from wide-angle seismic data and3-D gravity modeling” by Dellong et al.Geochemistry, Geophysics, Geosyste ms,21, e2020GC009077, https://doi.org/10.1029/2020GC009077

Description: Andrea Argnani in his comment on Dellong et al. (2020, https://doi.org/10.1029/2019gc008586) (Geometry of the deep Calabrian subduction (Central Mediterranean Sea) from wide‐angle seismic data and 3‐D gravity modeling) proposes an alternate interpretation of the wide‐angle seismic velocity models presented by Dellong et al. (2018, https://doi.org/10.1002/2017JB015312) and Dellong et al. (2020) and proposes a correction of the literature citations in these paper. In this reply, we discuss in detail all points raised by Andrea Argnani.

Description: Published

Description: e2020GC009223

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: The Comoros archipelago is an active geodynamic region of intra-plate volcanism within which the youngest and oldest islands (Grande Comore and Mayotte respectively) are characterized by recent volcanic activity. The frequent eruptions of the large shield volcano Karthala on Grande Comore (last eruption 2007), and the recent birth of a large submarine volcano since 2018 at the submarine base of Mayotte are associated with permanent fumarolic emissions, bubbling gas seeps, and soil gas emissions, which are studied in detail here for the first time. CO2 fluxes and chemical and isotopic gas compositions acquired during two surveys in 2017 and 2020 are integrated with older datasets collected between 2005 and 2016, permitting the identification of a possible influence of the recent volcanic and magmatic activity at Mayotte. At Karthala, high gas fluxes with high temperature, and a marked magmatic signature are concentrated close to the summit crater area, while only weaker emissions with a stronger biogenic signature are found on the volcano flanks. At Mayotte, lower temperature and higher CH4 content are recorded in two main seep areas of CO2-rich fluid bubbling, while soil emissions on land record a higher proportion of magmatic fluids compared to Karthala. Our preliminary results reveal two quite separate gas emission patterns for each island that are distinct in composition and isotopic signatures, and well-correlated with the present state of volcanic activity. This work may potentially provide support for local observation infrastructures and contribute to the improvement in volcanic and environmental monitoring.

Description: INGV (GECO project Fondi Ricerca libera 2019 INGV) and REVOSIMA Initiative (IPGP, CNRS, BRGM, IFREMER)

Description: Submitted

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: A number of oil- and gas-producing leases have been operating in Italy in the last decades, many of which are located in the surroundings of tectonically active regions. Identifying human-induced seismicity in areas with high levels of natural seismicity is a difficult task for which virtually any result can be a source of controversy. We implemented a large-scale analysis aiming at tracking significant departures of background seismicity from a stationary behavior around active oil and gas development leases in Italy. We analyzed seismicity rates before and after hydrocarbon peak production in six oil-producing and 43 gas-producing leases, and evaluate the significance of possible seismicity rate changes. In a considerable number of cases seismicity rate results stationary. None of the observed cases of seismicity rate increase after the peak production is statistically significant (at a s.l. = 0.05). Conversely, considering cases of seismicity rate decrease after peak production, our results suggest that the seismicity rate reduction is statistically significant (s.l. = 0.05) around one oil-producing lease (Val d’Agri, Basilicata) and around a cluster of gas-producing leases in Sicily. Our results put in evidence correlated changes between the rates of shallow seismicity and hydrocarbon production in these areas, which are then identified as hotspots requiring more detailed research; assessing actual causal relationships between these processes will require further physically-based modelling. If a physical causative link between these processes exists, then the observed seismicity rate reduction could either be due to increased seismicity during the progressive increase in production before reaching its maximum, or to an actual seismicity rate reduction after that peak. Considering that there is evidence of seismicity occurring before the start of hydrocarbon production, which contrasts with the evident reduction of events observed after the peak production, we think it likely that the seismicity inhibition is a plausible hypothesis. Using a simple model we also calculate Coulomb stress changes in planes optimally oriented for failure, and we show that under some conditions the inhibition of seismicity is feasible in at least one of these cases. We conclude that more efforts to study the mechanisms and the possible consequences of anthropogenically-driven seismicity inhibition are required.

Description: This study was performed with the support of Clypea, the Innovation Network for Future Energy financed by the Italian Ministry of Economic Development, Direzione Generale per le Infrastrutture e la Sicurezza dei Sistemi Energetici e Geominerari (MISE—DGISSEG)

Description: Published

Description: 673124

Description: 4T. Sismicità dell'Italia

Description: JCR Journal

Description: Seismic and geodetic moment-rate comparisons can reveal regions with unexpected potential seismic hazards. We performed such a comparison for the Southeastern Iberia—Maghreb region. Located at the western Mediterranean border along the Eurasia–Nubia plate convergence, the region has been subject to a number of large earthquakes (M ≥ 6.5) in the last millennium. To this end, on the basis of available geological, tectonic, and seismological data, we divided the study area into twenty-five seismogenic source zones. Many of these seismogenic source zones, comprising the Western Betics, the Western Rif mountains, and the High, Middle, and Saharan Atlas, are characterized by seismic/geodetic ratio values lower than 23%, evidencing their prevailing aseismic behavior. Intermediate seismic/geodetic ratio values (between 35% and 60%) have been observed for some zones belonging to the Eastern Betics, the central Rif, and the Middle Atlas, indicating how crustal seismicity accounts only for a moderate fraction of the total deformation-rate budget. High seismic/geodetic ratio values (〉 95%) have been observed along the Tell Atlas, highlighting a fully seismic deformation.

Description: The research performed in this study was partially supported by the Spanish CGL2015-65602-R, CGL2016-80687-R and RTI2018-093874-B-100 projects, and the Programa Operativo FEDER Andalucía 2014-2020 – call made by the University of Jaén 2018.

Description: Published

Description: 952

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Gases present in the Earth crust are important in various branches of human activities. Hydrocarbons are a significant energy resource, helium is applied in many high-tech instruments, and studies of crustal gas dynamics provide insight in the geodynamic processes and help monitor seismic and volcanic hazards. Quantitative analysis of methane and CO2 migration is important for climate change studies. Some of them are toxic (H2S, CO2, CO); radon is responsible for the major part of human radiation dose. The development of analytical techniques in gas geochemistry creates opportunities of applying this science in numerous fields. Noble gases, hydrocarbons, CO2, N2, H2, CO, and Hg vapor are measured by advanced methods in various environments and matrices including fluid inclusions. Following the “Geochemical Applications of Noble Gases”(2009), “Frontiers in Gas Geochemistry” (2013), and “Progress in the Application of Gas Geochemistry to Geothermal, Tectonic and Magmatic Studies” (2017) published as special issues of Chemical Geology and “Gas geochemistry: From conventional to unconventional domains” (2018) published as a special issue of Marine and Petroleum Geology, this volume continues the tradition of publishing papers reflecting the diversity in scope and application of gas geochemistry.

Description: Published

Description: 976190

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: We provide a dataset of 3D coordinate time series of 37 continuous GNSS stations installed for stability monitoring purposes on onshore and offshore industrial settlements along a NW-SE-oriented and ~100-km-wide belt encompassing the eastern Italian coast and the Adriatic Sea. The dataset results from the analysis performed by using different geodetic software (Bernese, GAMIT/GLOBK and GIPSY) and consists of six raw position time series solutions, referred to IGb08 and IGS14 reference frames. Time series analyses and comparisons evidence that the different solutions are consistent between them, despite the use of different software, models, strategy processing and frame realizations. We observe that the offshore stations are subject to significant seasonal oscillations probably due to seasonal environmental loads, seasonal temperature-induced platform deformation and hydrostatic pressure variations. Many stations are characterized by non-linear time series, suggesting a complex interplay between regional (long-term tectonic stress) and local sources of deformation (e.g. reservoirs depletion, sediment compaction). Computed raw time series, logs files, phasor diagrams and time series comparison plots are distributed via PANGAEA ( https://www.pangaea.de ).

Description: This research was financed by the Italian Economic Development Ministry in the”CLYPEA-Innovation Network for Future Energy” framework, “subsoil deformations” project.

Description: Published

Description: 373

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 settembre al 31 dicembre 2020 ha riguardato tutti i terremoti di magnitudo M≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale valore sono quelli calcolati in tempo reale, nella sala di sorveglianza sismica di Roma. I terremoti più forti (M≥3.5), e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag-6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: 4IT. Banche dati

Description: The E-vergent Northern Apennines formed by Oligocene-Miocene convergence and westward subduction of Adria beneath Europe. Extension ensued in the Mid-Late Miocene reflecting lower plate roll-back and causing opening of the back-arc Northern Tyrrhenian Sea. Post-orogenic extension is commonly advocated as the main driver of the exhumation of the belt's inner domain highpressure/ low-temperature (HP-LT) rock units. The Acquadolce Subunit of the Eastern Elba nappe stack contains HP-LT rocks recording peak blueschist conditions of 1.5–1.8 GPa at 320°C–370°C loosely dated to the Oligocene-Early Miocene. It is sandwiched by two Late Miocene, out-of-sequence top-to-the E thrusts between Jurassic LP serpentinites on top and HT–LP contact metamorphosed marbles at its base. We document widespread W-verging ductile asymmetries within the Acquadolce Subunit, which correspond to top-to-the W extensional shearing for the nappe stack current orientation. This allowed for early syn-orogenic exhumation from blueschist- to greenschist-facies conditions, wherein coeval W-directed extension at the top of the exhuming units acted synchronously with E-directed thrusting at their base causing exhumation by extrusion in an overall contractional setting. The basal, E-vergent thrusting is, however, challenging to document as the wedge has since been reworked by Late Miocene, E-verging compressive tectonics, contact metamorphism, and later extension, obliterating much of the evidence supporting exhumation by extrusion during the early stages of wedge build-up. Syn-orogenic exhumation by extrusion from deep structural levels within the orogenic wedge is a viable mechanism to account for other exhumed HP-LT units in the inner part of the belt.

Description: Published

Description: e2020TC006348

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: EarthScope's USArray seismic component provided unprecedented coverage of the contiguous United States and has therefore spurred significant advances in tomographic imaging and geodynamic modelling. Here, we present a new global, radially anisotropic shear wave velocity tomography model to investigate upper mantle structure and North American Plate dynamics, with a focus on the contiguous United States. The model uses a data-adaptive mesh and traveltimes of both surface waves and body waves to constrain structure in the crust and mantle in order to arrive at a more consistent representation of the subsurface compared to what is provided by existing models. The resulting model is broadly consistent with previous global models at the largest scales, but there are substantial differences under the contiguous United States where we can achieve higher resolution. On these regional scales, the new model contains short wavelength anomalies consistent with regional models derived from USArray data alone. We use the model to explore the geometry of the subducting Farallon Slab, the presence of upper mantle high velocity anomalies, low velocity zones in the central and eastern United States and evaluate models of dynamic topography in the Cordillera. Our models indicate a single, shallowly dipping, discontinuous slab associated with the Farallon Plate, but there are remaining imaging challenges. Inferring dynamic topography from the new model captures both the long-wavelength anomalies common in global models and the short-wavelength anomalies apparent in regional models. Our model thus bridges the gap between high-resolution regional models within the proper uppermost mantle context provided by global models, which is crucial for understanding many of the fundamental questions in continental dynamics.

Description: Published

Description: 1730–1746

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: In the last years, several studies investigated the Mt. Vettore Fault Zone (MVFZ), activated during the 2016 Central Italy seismic sequence. Research has focused mainly on aftershocks and mainshock locations, coseismic slip and surface cracks, while an accurate study of the fracture network in the MVFZ was never conducted. In this study we present a fracture analysis performed using very high resolution (0.5 – 5 cm) Digital Outcrop Models (DOMs) that developed by Unmanned Aerial Vehicle (UAV)-based digital photogrammetry. The UAV gave the possibility to investigate outcrops with dimensions up to hundreds of metres high and wide, and acquire big and precise fracture data using 3D digital automatic and manual mapping techniques. To investigate the structural variability of the MVFZ fracture network, we realized several DOMs located in different positions, along and around the major fault. All the selected outcrops are formed by Calcare Massiccio Fm., which better records brittle deformation in the study area. This analysis aimed to better understand the MVFZ fracture network, including mechanics, kinematics and local structural evolution. In particular, it allowed to determine: 1) the main sets of fractures; 2) the geometrical parameters of the fracture network (e.g. fracture density, persistence, roughness and aperture); 3) the relative timing of the main tectonic brittle events. The preliminary analysis of the DOMs suggests a variability of the fracture network parameters over the MVFZ, especially for what concerned fracture set orientation and density.

Description: Published

Description: vEGU21: Virtual Conference Online

Description: 2T. Deformazione crostale attiva

Description: Several hypotheses on the origin of the continental Moho are still debated and multiple mechanisms may contribute to its formation. Here, we present quantitative estimation of the seismic properties and anisotropy of the crust-mantle transition in the Western Alps where an example of newly formed (proto)-continental Moho is unusually shallow. We make use of teleseismic P-to-S converted-waves recorded by stations deployed on top of the Ivrea Body (IB), a volume of possibly serpentinized mantle peridotite below exhumed (ultra-)high pressure crustal rocks. The IB has been mapped by gravity, magnetic, active and passive seismic surveys suggesting an extremely shallow Moho. We demonstrate that the P-to-S converted waves propagating through this region display coupled features: (a) they record expected presence of strong seismic velocity contrast at shallow depth as due to the lower crustal and upper mantle transition; (b) they are decomposed due to anisotropic properties of rocks involved. The proto-continental Moho is recognized as an increase in S-wave velocity (∼0.4-1 km/s) at shallow depths of 5-10 km. The presence of anisotropy within the IB and overlying crustal rocks is evidenced by back-azimuthal dependence of the amplitude of P-to-S phases. The strength of anisotropy is ∼-14% on average pointing out the presence of metamorphosed/hydrated material (e.g., serpentinite) below the Moho. Anisotropic directions are consistent across Moho in both crust and upper mantle. The similarity of the anisotropy parameters between crust and upper mantle suggests they have been shaped by the same deformation event.

Description: Published

Description: e2020JB021319

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 maggio al 31 agosto 2020 ha riguardato tutti i terremoti di magnitudo M≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale valore sono quelli calcolati in tempo reale, nella sala di sorveglianza sismica di Roma. I terremoti più forti (M≥3.5), e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag-6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: 4IT. Banche dati

Description: La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 gennaio al 30 aprile 2021 ha riguardato tutti i terremoti di magnitudo M≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (M≥3.5) e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag-6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: 4IT. Banche dati

Description: Pisciarelli, together with the adjacent Solfatara maar-diatreme, represents the most active structure of the Campi Flegrei caldera (Italy) in terms of degassing and seismic activity. This paper aims to define the structure of the Pisciarelli hydrothermal system (down to a 20 m depth) through electrical resistivity and time-domain-induced polarization tomography and self-potential mapping. The retrieved 3D image of the area helps reconstruct the Pisciarelli subsurface in its area of maximum degassing, containing the main fumarole ("soffione") and the mud pool. In particular, a channel has been identified in which fluids stored in a deeper reservoir rise toward the surface. Such a structure seems to be surmounted by a clay-cap formation that could govern the circulation of fluids and the abundance of gases/vapors emitted by the soffione. Based on this new reconstruction of the Pisciarelli fumarolic field structural setting, the first conceptual model has been suggested that is capable of simultaneously explaining the mechanisms governing soffione activity and elucidating the role played by the fluid/gas of deeper origin in the shallow fluid circulation system. The proposed model can potentially help to better monitor the processes occurring throughout the Pisciarelli fumarolic field and provide an evaluation of the associated hazards.

Description: Published

Description: 18639

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: The Western Ionian Sea is characterised by an active and diffuse seismicity, directly related to the convergence of the European and African Plates and by gravitational sinking and rollback of the oceanic lithosphere. In this area, the location of earthquakes is characterised by considerable uncertainties due to large azimuthal gaps, resulting in notable location errors. This problem was partially overcome with the use of data recorded by NEMO-SN1 seafloor observatory (October 2002 - February 2003; June 2012 - May 2013). We relocated 1130 crustal and sub-crustal earthquakes using land network and NEMO-SN1 data. As most events occurred on Mt. Etna, we focused on 358 earthquakes in the offshore area and near the coasts of Sicily and Calabria. The use of the combined land-marine networks has improved the earthquake locations in terms of azimuthal GAP, as well as in horizontal and vertical errors. The comparison between locations performed with and without NEMO-SN1 data shows that differences in latitude, longitude and depths are more evident in the Western Ionian Sea and in the coast of Sicily, where values of the differences over 5 km correspond to structural heterogeneities. The increased number of seismic stations deployed on land from 2003 to 2012 did not influence the location of events occurring offshore, where NEMO-SN1 continued to be the distinctive tool in the location process. Moreover, the new 73 focal mechanisms computed with P-wave polarities from NEMO-SN1 and land stations are in agreement with the regional structural model, showing a prevalent normal, normal/oblique, and strike-slip kinematics. The similarity of two new focal solutions with the mechanisms of the main shock and aftershock of the 1990 earthquake demonstrates that the seismic structures are still active and potentially dangerous. The P-wave travel time residual analysis confirms the activity along the main structural alignments. A single point of observation in the Ionian Sea can significantly improve the quality of locations, giving an opportunity to focus on the seismogenic structures responsible for the occurrence of medium-to-high magnitude earthquakes.

Description: Published

Description: Se655

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: The comparison between crustal stress and surface strain azimuthal patterns has provided new insights into several complex tectonic settings worldwide. Here, we performed such a comparison for Egypt taking into account updated datasets of seismological and geodetic observations. In north-eastern Egypt, the stress field shows a fan-shaped azimuthal pattern with a WNW–ESE orientation on the Cairo region, which progressively rotated to NW–SE along the Gulf of Aqaba. The stress field shows a prevailing normal faulting regime, however, along the Sinai/Arabia plate boundary it coexists with a strike–slip faulting one (σ1 ≅ σ2 〉 σ3), while on the Gulf of Suez, it is characterized by crustal extension occurring on near-orthogonal directions (σ1 〉 σ2 ≅ σ3). On the Nile Delta, the maximum horizontal stress (SHmax) pattern shows scattered orientations, while on the Aswan region, it has a WNW–ESE strike with pure strike–slip features. The strain-rate field shows the largest values along the Red Sea and the Sinai/Arabia plate boundary. Crustal stretching (up to 40 nanostrain/yr) occurs on these areas with WSW–ENE and NE–SW orientations, while crustal contraction occurs on northern Nile Delta (10 nanostrain/yr) and offshore (~35 nanostrain/yr) with E–W and N–S orientations, respectively. The comparison between stress and strain orientations over the investigated area reveals that both patterns are near-parallel and driven by the same large-scale tectonic processes.

Description: This research was partially funded by the Programa Operativo FEDER Andalucía 2014-2020—A call made by the University of Jaén 2018.

Description: Published

Description: 1398

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: A comparative analysis of geodetic versus seismic moment-rate estimations makes it possible to distinguish between seismic and aseismic deformation, define the style of deformation, and also to reveal potential seismic gaps. This analysis has been performed for Egypt where the present-day tectonics and seismicity result from the long-lasting interaction between the Nubian, Eurasian, and Arabian plates. The data used comprises all available geological and tectonic information, an updated Poissonian earthquake catalog (2200 B.C.–2020 A.D.) including historical and instrumental datasets, a focal-mechanism solutions catalog (1951–2019), and crustal geodetic strains from Global Navigation Satellite System (GNSS) data. The studied region was divided into ten (EG-01 to EG-10) crustal seismic sources based mainly on seismicity, focal mechanisms, and geodetic strain characteristics. The delimited seismic sources cover the Gulf of Aqaba–Dead Sea Transform Fault system, the Gulf of Suez–Red Sea Rift, besides some potential seismic active regions along the Nile River and its delta. For each seismic source, the estimation of seismic and geodetic moment-rates has been performed. Although the obtained results cannot be considered to be definitive, among the delimited sources, four of them (EG-05, EG-06, EG-08, and EG-10) are characterized by low seismic-geodetic moment-rate ratios (〈20%), reflecting a prevailing aseismic behavior. Intermediate moment-rate ratios (from 20% to 60%) have been obtained in four additional zones (EG-01, EG-04, EG-07, and EG-09), evidencing how the seismicity accounts for a minor to a moderate fraction of the total deformational budget. In the other two sources (EG-02 and EG-03), high seismic-geodetic moment-rates ratios (〉60%) have been observed, reflecting a fully seismic deformation

Description: This research has been partially funded in the frame of the Programa Operativo FEDER Andalucía 2014–2020-call made by the University of Jaén, 2018.

Description: Published

Description: 7836

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Abstract The Lisbon Metropolitan Area, Portugal, has been affected by several destructive earthquakes nucleating both along the offshore Africa-Eurasia plate boundary and on onshore inherited intraplate faults. Using a dense GNSS dataset coupled with PSInSAR analysis, we provide new evidence of sinistral simple shear driven by a NNE-SSW first-order tectonic lineament. PSInSAR vertical velocities corroborate qualitatively the GNSS strain-rate field, showing uplift/subsidence where the GNSS data indicate contraction/extension. We propose the presence of a small block to the W of Lisbon moving independently toward the SW with a relative velocity of 0.96 ± 0.20 mm/yr, whose boundaries are part of a complex and as yet poorly constrained strike-slip fault system, possibly rooting at depth into a simpler basement fault. Comparison between geodetic and seismic moment-rates indicates a high seismic coupling. We show that the contribution of intraplate faults to the seismic hazard in the LMA is more important than currently assumed.

Description: FCT - Fundação para a Ciência e a Tecnologia, Lisbon. Grant Number: EXCL/GEO-FIQ/0411/2012 Agencia Española de Investigacion. Grant Number: RTI2018-093874-B-100 AGEO - Platform for Atlantic Geohazard Risk Management. Grant Number: EAPA_884/2018

Description: Published

Description: e2021GL096862

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Wehmiller, J. F., Brothers, L. L., Ramsey, K. W., Foster, D. S., Mattheus, C. R., Hein, C. J., & Shawler, J. L. Molluscan aminostratigraphy of the US Mid-Atlantic Quaternary coastal system: implications for onshore-offshore correlation, paleochannel and barrier island evolution, and local late Quaternary sea-level history. Quaternary Geochronology, 66, (2021): 101177, https://doi.org/10.1016/j.quageo.2021.101177.

Description: The Quaternary record of the US Mid-Atlantic coastal system includes onshore emergent late Pleistocene shoreline deposits, offshore inner shelf and barrier island units, and paleovalleys formed during multiple glacial stage sea-level lowstands. The geochronology of this coastal system is based on uranium series, radiocarbon, amino acid racemization (AAR), and optically stimulated luminescence (OSL) methods. We report over 600 mollusk AAR results from 93 sites between northeastern North Carolina and the central New Jersey shelf, representing samples from both onshore cores or outcrops, sub-barrier and offshore cores, and transported shells from barrier island beaches. AAR age estimates are constrained by paired 14C analyses on specific shells and associated U-series coral ages from onshore sites. AAR data from offshore cores are interpreted in the context of detailed seismic stratigraphy. The distribution of Pleistocene-age shells on the island beaches is linked to the distribution of inner shelf or sub-barrier source units. Age mixing over a range of time-scales (~1 ka to ~100 ka) is identified by AAR results from onshore, beach, and shelf collections, often contributing insights into the processes forming individual barrier islands. The regional aminostratigraphic framework identifies a widespread late Pleistocene (Marine Isotope Stage 5) aminozone, with isolated records of middle and early Pleistocene deposition. AAR results provide age estimates for the timing of formation of the three major paleochannels that underlie the Delmarva Peninsula: Persimmon Point paleochannel ≥800 ka; Exmore paleochannel ~400–500 ka (MIS 12); and Eastville paleochannel 〉 125 ka (MIS 6). The results demonstrate the value of synthesizing abundant AAR chronologic data across various coastal environments, integrating multiple distinct geologic studies. The ages and elevations of the Quaternary units are important for current hypotheses about relative sea-level history and crustal dynamics in the region, which was likely influenced by the Laurentide ice sheet, the margin just ~400 km to the north.

Description: This project was funded through a cooperative agreement with the Bureau of Ocean Energy Management of the U.S. Department of the Interior, Offshore Sand Resources for Coastal Resilience and Restoration Planning: M14AC00003 and M16AC00001. We thank J. Waldner (BOEM) for support and encouragement during this project. We also thank S. Howard and K. Luciano, South Carolina Geological Survey, and numerous colleagues in both the Mid-Atlantic and Southeast Atlantic BOEM ASAP projects, active from 2015 through 2019. This paper is contribution #3999 of the Virginia Institute of Marine Science, William & Mary. Partial support was also provided to Hein by the Mid-Atlantic Sea Grant program (NOAA) award numbers R/71856G and R/71856H and a Virginia Sea Grant (NOAA) Fellowship award NA18OAR4170083 supported Shawler. JFW acknowledges support from the University of Delaware Retired Faculty Research Program.

Description: This work analyses six high-resolution multi-channel seismic profiles across the Klints Bank east of Gotland. The Klints Bank consists of a drop-shaped increase of the Quaternary thickness and is oriented in an approximately north-southern direction with a length of over 50 km, a width of about 15 km and a maximum thickness of 150 m. The glacial origin of the Klints Bank can be verified with the dataset presented in this study. We classify the feature as a (giant) drumlin due to its steep up-ice and tapered down-ice face in combination with an orientation parallel to the ice-flow direction of the Weichselian glaciation. The seismic image of the internal structure of the Quaternary unit shows no uniform stratification or deformation patterns; instead, local sub-parallel reflection patterns interlayered with transparent units are observed. The averaged seismic velocity of this unit is about 2000 m/s, which is interpreted as an autochthonous deposition of glaciogenic sediments. Signs of overprinting are interpreted based on the geometry of the flanks of the structure, which appear mostly in the form of collapse structures and lifted blocks due to compressional thrust faulting. Phase-reversed events within and beneath the Quaternary are perceived as strong evidence of fluid (hydrocarbon) presence within the Klints Bank. Organically enriched Palaeozoic shales in south-easterly direction of the Klints Bank presumably give the origin of these thermogenic hydrocarbons.

Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Description: This study presents a detailed analysis of minor seismic sequences recorded in the Amatrice-Norcia area (central Italy) before 2016 when the most important seismic sequence of the last 40 years struck the region with the Mw 6.0 Amatrice and the Mw 6.5 Norcia earthquakes. We observe that, in the four decades before the 2016–2018 Amatrice-Visso-Norcia sequence, the instrumental seismicity rate is low, with maximum magnitudes lower than Mw 4.0, and is characterized by different types of behaviours as single shock events, swarms and minor se- quences. For the first time, we relocate the minor seismicity recorded before 2016 by the Italian National Seismic Network of the Istituto Nazionale di Geofisica e Vulcanologia by applying the nonlinear inversion code Non- LinLoc in a local velocity model. Revised earthquake locations of the past seismic sequences are compared to the recent 2016–2018 seismicity in order to investigate some possible correlations with the seismogenic structures reactivated in 2016. With this goal, we also integrated our new hypocentral locations with fault plane solutions and geological data to interpret our results with respect to the 2016–2018 seismicity. Our results show how some of the structures identified by the minor seismicity before 2016 were reactivated during the recent sequence, while others seismic structures remained silent. We therefore highlight how the study of minor seismic sequences provides important information about the seismogenic attitude of less active or less known seismogenic struc- tures with consequent impact on the evaluation of the seismic hazard.

Description: Published

Description: 228858

Description: 4T. Sismicità dell'Italia

Description: JCR Journal

Description: The identification and characterization of seismogenic structures in southwestern Sicily is an open debate both for the geological-structural complexity of this sector and the scarce seismicity as well. In addition, clear morphological evidence of tectonic structures is limited. Besides the geophysical methods, the study of the spatial distribution of soil CO2 flux is a valid methodology to investigate the position and geometry of buried active faults. Indeed, active tectonic structures are channels with high permeability through which deep fluids can migrate toward the atmosphere. Therefore, the alignment of high degassing areas can reveal the presence of preferential ways of rising fluids (i.e. faults). We applied this methodology in SW Sicily in the surrounding of the area hit by the 1968 seismic sequence and in three other areas where evidence of active deformation has been recognized. Furthermore, to investigate the origin of emitted fluids, we measured the carbon isotopic composition of the soil CO2 in some high emission sites. The results showed high spatial variability of soil CO2 fluxes with values ranging from 1 to 430 g m−2d−1. The areal patterns of soil CO2 fluxes in all the areas reveal a strong influence of the main tectonic structures and active deformations on soil CO2 emissions. The range of isotopic data and the distribution of soil CO2 fluxes suggest a supply of deep fluids through the active tectonic structures.

Description: Published

Description: SE104

Description: 2T. Deformazione crostale attiva

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: Infrasound is an increasingly popular tool for volcano monitoring, providing insights of the unrest by detecting and characterizing acoustic waves produced by volcanic processes, such as explosions, degassing, rockfalls, and lahars. Efficient event detection from large infrasound databases gathered in volcanic settings relies on the availability of robust and automated workflows. While numerous triggering algorithms for event detection have been proposed in the past, they mostly focus on applications to seismological data. Analyses of acoustic infrasound for signal detection is often performed manually or by application of the traditional short-term average/long-term average (STA/LTA) algorithms, which have shown limitations when applied in volcanic environments, or more generally to signals with poor signal-to-noise ratios. Here, we present a new algorithm specifically designed for automated detection of volcanic explosions from acoustic infrasound data streams. The algorithm is based on the characterization of the shape of the explosion signals, their duration, and frequency content. The algorithm combines noise reduction techniques with automatic feature extraction in order to allow confident detection of signals affected by non-stationary noise. We have benchmarked the performances of the new detector by comparison with both the STA/LTA algorithm and human analysts, with encouraging results. In this manuscript, we present our algorithm and make its software implementation available to other potential users. This algorithm has potential to either be implemented in near real-time monitoring workflows or to catalog pre-existing databases.

Description: This research was partially funded by KNOWAVES TEC2015- 68752 (MINECO/FEDER), by NERC Grant NE/P00105X/1, by Spanish research grant MECD Jose Castillejo CAS17/00154 and by VOLCANOWAVES European Union’s Horizon 2020 Research and Innovation Programme Under the Marie Sklodowska-Curie Grant Agreement no 798480.

Description: Published

Description: Article 335

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: This paper presents a detailed geological map at the 1:20,000 scale of the Tocomar basin in the Central Puna (north-western Argentina), which extends over an area of about 80 km2 and displays the spatial distribution of the Quaternary deposits and the structures that cover the Ordovician basement and the Tertiary sedimentary and volcanic units. The new dataset includes litho-facies descriptions, stratigraphic and structural data and new 234U/230Th ages for travertine rocks. The new reconstructed stratigraphic framework, along with the structural analysis, has revealed the complex evolution of a small extensional basin including a period of prolonged volcanic activity with different eruptive centres and styles. The geological map improves the knowledge of the geology of the Tocomar basin and the local interplay between orogen-parallel thrusts and orogen-oblique fault systems. This contribution represents a fundamental support for in depth research and also for encouraging geothermal exploration and exploitation in the Puna Plateau region.

Description: Published

Description: id 5492

Description: 1TR. Georisorse

Description: JCR Journal

Description: Normal fault systems, outcropping or hidden below Quaternary covers in intermountain basins, are the expression of the Neogene-Quaternary evolution of central Italy, characterized by an extensional tectonic regime following the fold and thrust structuring of the Appenninic orogen. The presence of these features plays an important role in seismic risk evaluation of an area. In this work we deal with the use of single-station seismic noise measurements to detect sudden lateral variations of the geometries and/or properties of subsoil connected to the presence of tectonic elements (fault zones). Ambient noise data were collected along transects perpendicular to the strike of hypothetical fault lines for 3 test sites within the Abruzzi Region. The proposed approach is suitable for detecting in a fast and simple way local lateral changes in the subsoil characteristics close to geological structures and can be very effective to properly address more expensive and time consuming classical geophysical and paleoseismological approaches.

Description: Published

Description: Pescina, Fucino Basin, Italy

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: In this work we tested the capability of single station ambient noise spectral ratios (HVNSR) technique to be used as a proxy for detecting sharp variations in the subsoil characteristics in sedimentary basins. In sites characterized by 1D response HVNSR is able to detect the resonance frequency of sediments (f0) to be related with their thickness and velocity. In quasi-1D geological situation, a smooth variation in the resonance frequency suggests some variation in the thickness of the soft sedimentary layers or in their velocity. In the case of sharp lateral variation of the subsoil, as in presence of morphological steps or buried faults in the bedrock, the noise wave-field becomes more complex and spectral ratios show some directional effect strictly related to the presence of the lateral heterogeneity (Matsushima et al. 2014). In this work we focus our attention on the detection of a buried shallow tectonic element known in bibliography (Galadini, Galli 1999) as the Luco dei Marsi fault, located in the western margin of the Fucino basin (central Appenines, Italy). We performed simultaneous ambient noise measurements using MarsLite digitizers equipped with Lennarts 3d-5s velocimeters along a transect, with inter-station distance between 30 and 50 meters, which crosses perpendicularly the surface projection of fault line. The collected data, analyzed with classical HVNSR technique, show some complexities in the f0 distribution compatible with the presence of the buried fault. In detail, our results highlight a 1D response with a clear resonance peak for the stations located away from the fault. Moving closer to the fault line, where the 1D condition is not verified, the resonance peak becomes broader. Directional analysis of spectral ratios suggests the dependence of the noise wave-field to the presence of the fault line. Close to the geological feature, results of directional analysis show a doubling in the resonance frequency with relative amplitudes changing for fault-parallel and fault-normal direction of polarization. To support with an independent approach our observations, an electrical resistivity tomography was performed along the transect whose results show the presence of a clear step in a high resistivity shallow layer that can be assumed as the bedrock. After this analysis we decided to extend the ambient noise transect towards the centre of the basin where no fault line is mapped and where we expected a smooth lowering of f0 values due to the deepening of the bedrock. This feature was really observed for a while but at a distance between 400 and 500 meters from the Luco fault we detected again some anomaly in HVNSR data with a doubling of resonance frequency and relative amplitudes depending from the direction of polarization. This observation suggests the presence of deeper tectonic element parallel to the Luco fault. As a conclusion of our work we believe that HVNSR and polarization analysis can represent a quick and fast method to hypothesize the presence of buried discontinuity in the subsoil and can be usefully used to guide the positioning of more sophisticated geophysical analysis aimed at mapping their geometries.

Description: Published

Description: Trieste, Italy

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: The partitioning of carbon dioxide (CO〈sub〉2〈/sub〉) released by soils at Vulcano Island (Aeolian Islands, Italy) was performed by combining the CO〈sub〉2〈/sub〉 flux and the carbon isotope measurements. Based on this method, the amount of CO〈sub〉2〈/sub〉 of volcanic origin was quantified six times during the period 2015–2018. The data analysis allowed us to establish the correlation between CO〈sub〉2〈/sub〉 soil degassing and changes in the contribution of volcanic fluids. Carbon isotope determinations were performed in situ to enhance the coverage of data collection in space and time. These data were combined with both the CO〈sub〉2〈/sub〉 contents in the ground gases and the soil CO〈sub〉2〈/sub〉 flux. The amount of volcanic CO〈sub〉2〈/sub〉 was distinguished from that of biogenic origin by implementing a three-component mixing model. The results of this study indicate that the increase in CO〈sub〉2〈/sub〉 output in September 2018 reflects the increase in volcanic gas emissions. The measurement method and analysis presented in this work are sufficiently general to be applicable to the monitoring programs of active volcanoes.

Description: Published

Description: 106972

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: Highlights -Gas blowouts from water wells are frequent in the southeastern zone of Rome -Emitted gas killed some pets and families had to be evacuated for security reasons -Gas has a magmatic origin with the highest helium R/Ra of Colli Albani gas discharges -Monitoring of soil CO2 flux and air gas concentration allowed to assess gas hazard -Gas diffusing in soil reached nearby houses creating dangerous indoor conditions

Description: The southeastern zone of Rome city is located at the northwest periphery of the quiescent Colli Albano volcano. This zone is characterized by the presence of a shallow (depth ~ 45–50 m) gas pressurized aquifer that produces gas blowouts when it is reached by wells. Three gas blowouts occurred in this zone in 2003, 2008 (another one was discovered during the present study) and 2016 and in this paper we describe in detail the latter two. The emitted gas consists mostly of CO2 (〉90 vol%) and contains a low but significant quantity of H2S (0.3–0.5 vol%) and it has the highest helium isotopic R/Ra value (1.90) of all Colli Albani natural gas discharges, suggesting its likely magmatic origin. In both the described gas blowouts, dozens of families had to be prudentially evacuated from their houses and the emitted gas killed some animals. We monitored, continuously or by discrete surveys, the soil CO2 flux, the indoor and outdoor air concentration of CO2 and H2S, the environmental parameters and we checked whether the cementation of the gas releasing wells had been effective. In both cases, the upper part of the wells had been partly closed with an inflating packer to avoid free gas dispersion in atmosphere; as a consequence gas diffused laterally from the wells into the permeable surficial soil up to reach the nearest houses creating hazardous indoor conditions, particularly for CO2 in some basements. During the well cementation operations, and in one case because of the packer rupture, gas and nebulized water were freely discharged from the wells into the atmosphere, and high air CO2 and H2S concentrations were found. Fortunately gas was quickly dispersed by strong winds. The positive results obtained in all the studied gas blowouts demonstrate that our applied geochemistry approach represents a model of intervention useful for the assessment of the hazard associated to accidental endogenous gas release. This model is of fundamental importance also to overcome the risk problems created by accidental gas blowout from wells in an urbanized environment, up to the safe return of the people in their evacuated houses.

Description: Published

Description: 104769

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: Recent measurements of surface vertical displacements of the European Alps show a correlation between vertical velocities and topographic features, with widespread uplift at rates of up to ~2–2.5 mm/a in the North-Western and Central Alps, and ~1 mm/a across a continuous region from the Eastern to the South-Western Alps. Such a rock uplift rate pattern is at odds with the horizontal velocity eld, characterized by shortening and crustal thickening in the Eastern Alps and very limited deformation in the Central and Western Alps. Proposed me- chanisms of rock uplift rate include isostatic response to the last deglaciation, long-term erosion, detachment of the Western Alpine slab, as well as lithospheric and surface de ection due to mantle convection. Here, we assess previous work and present new estimates of the contributions from these mechanisms. Given the large range of model estimates, the isostatic adjustment to deglaciation and erosion are su cient to explain the full observed rate of uplift in the Eastern Alps, which, if correct, would preclude a contribution from horizontal shortening and crustal thickening. Alternatively, uplift is a partitioned response to a range of mechanisms. In the Central and Western Alps, the lithospheric adjustment to deglaciation and erosion likely accounts for roughly half of the rock uplift rate, which points to a noticeable contribution by mantle-related processes such as detachment of the European slab and/or asthenospheric upwelling. While it is di cult to independently constrain the patterns and magnitude of mantle contributions to ongoing Alpine vertical displacements at present, future data should provide additional insights. Regardless, interacting tectonic and surface mass redistribution processes, rather than an individual forcing, best explain ongoing Alpine elevation changes.

Description: Published

Description: 589-604

Description: 1T. Struttura della Terra

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: The chemical and isotopic features of the fluids (water and gases) in the Lucane thermal area (southern Italy) have been investigated in order to verify their origin, water temperature in the geothermal reservoir, and to recognize the main natural processes concerning the water composition during ascent towards the surface. The Lucane geothermal system is placed in the southern sector of the Apennines chains, a seismically active area, close to the southern base of the Mt. Alpi carbonate massif. Along the study area, two main sets of high-angle faults form an almost orthogonal fault system that, as suggested by local structural geology, acts as a preferential pathway for uprising deep fluids. Here, we recognized two different types of waters: (i) cold shallow waters having a meteoritic origin and interacting with carbonate rocks (dolomite and calcite), whose dissolved gases show a dominant atmospheric contribution and (ii) hypothermal waters (average temperature of 21 °C), having a meteoritic origin and interacting with both carbonate rocks and inter-bedded evaporitic deposit. Geochemical data allow estimating a geothermal reservoir temperature between 30 °C and 60 °C, according to silica and Ca/ Mg geothermometers, respectively. A heat discharge related to hypothermal groundwater flow between 7.75E +06 and 2.00E+07 J/s was computed. δ18O and δ2Η data allowed recognizing a meteoric origin for hypothermal (hereafter TL) waters, with mean recharge (infiltration) elevations between 1300 and 1700 m a.s.l. These waters are gas-rich (e.g., CO2 and He), which amounts are higher than those in air-saturated water (ASW). Carbon and helium isotope signature in the TL waters indicate their mainly crustal origin and involve a tectonic control on fluid migration through the crust. Furthermore, we observe that the He isotopic signature in gases dissolved in TL waters is stable over time and its monitoring could be a powerful tool to assess the seismogenetic processes since their preparatory phases.

Description: Published

Description: 106618

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: The densely populated Po Plain, a very deep sedi- mentary basin in northern Italy, is prone to heavy shaking during earthquakes. Seismic hazard assessment must account for local variation in wave amplification. Standard ground motion prediction equations may fail to picture the complexity of strong lateral gradients in seismic response, due to sharp structural heterogeneity. For this reason, there is an increasing demand for full waveform predictions for engineering applications. Here, we present an implementation of a hybrid broadband simulation based on the method of Mai et al. (Bull Seismol Soc Am 100(6):3338–3339, 2010), to obtain complete broadband seismograms of 0.1–10 Hz. With this method, low frequency (〈1 Hz) and high frequency (1–10 Hz) seismograms are simulated separately using a deter- ministic and a stochastic method, respectively. We apply the method to four events recorded within the Po basin, with magnitude ranging from Mw = 4.4 to Mw = 5.6. The low frequency (LF) simulation is performed using SPECFEM3D on a few test sub- surface velocity models. The three-dimensional velocity model MAMBo (Molinari et al. in Bull Seismol Soc Am 105(2A):753–764, 2015)—consisting of a detailed structural description of the basin, based on extensive active-source data, embedded within a regional 3D crustal model—provided the best results for broadband simulations that most closely corresponded with the observations. It performed better than an ambient noise tomography model with more accurate S-wave velocities but less well defined layer topographies, emphasizing the importance of first order velocity discontinuities. The high frequency (HF) seis- mograms are simulated using the multiple scattering approach of Zeng et al. (J Geophys Res Solid Earth 96(B1):607–619, 1991). The scattering coefficients are obtained by performing a non linear inversion for each station to find best fitting synthetic envelopes. HF energy is then combined at 1 Hz to match the amplitude and phase spectra of the LF signal. We are able to simulate full waveforms throughout the Po Plain, of which shaking duration matches observed data for stations located in the basin. Shaking amplitudes are generally overestimated in the low frequency simulation by the MAMBo velocity model. Updating the MAMBo velocity model with more accurate S-wave velocity information of the ambient noise tomography model should improve the fit in future simulations.

Description: Published

Description: 2181–2198

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: This article has been accepted for publication in Geophysical Journal International ©: 2014, Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

Description: In this work, we present a study of the coseismic and post-seismic crustal deformation associ- ated to the Mw 6.3, 2009 April 6 L’Aquila earthquake from the analysis of GPS displacement time-series. We use a principal component decomposition-based inversion method to study the space- and time-dependent evolution of slip on faults without any a priori assumption on the model used to characterize the temporal evolution of crustal deformation. The method adopted allows us to account for the initial post-seismic deformation in estimating the coseismic dis- placements, in a consistent manner for the whole GPS network. We use elastic dislocation theory and a least-squares procedure to invert for the slip distribution on the mainshock fault (Paganica fault) and a second fault (Campotosto fault), where a Mw 5.2 aftershock occurred on April 9. The geometries for these faults are obtained from a singular value decomposition of precisely relocated aftershocks. We find that the use of complex fault geometries is not justified by the GPS observations available. An inversion that accounts for post-seismic slip to occur on both the Paganica and Campotosto faults provides a better fit to the GPS time-series observations, than using only the Paganica fault segment, at a 95 per cent confidence level. Within our resolution, afterslip regions do not migrate over time and are localized on fault patches that are approximately complementary to those of coseismic slip. We find that the position of some relevant afterslip patches is different if the inversion is performed assuming a fixed rake or not. We estimate the parameter a – b of rate- and state-dependent friction on those fault regions accommodating afterslip that are robustly characterized in our inversions. We find values of the order of 10−3, which is near the transition from potentially unstable to nominally stable friction. These results are in agreement with laboratory measurements performed on typical rocks of the L’Aquila region.

Description: Published

Description: 174–191

Description: 1T. Struttura della Terra

Description: 2T. Deformazione crostale attiva

Description: 3T. Sorgente sismica

Description: JCR Journal

Description: A new methodology is presented consisting of a multi-step procedure based on the integrated application of different diagnostic techniques aimed at recognizing altered and unaltered parts of architectural elements of ancient buildings and at identifying zones where structural damage has occurred on their surface. The methodology was tested on a historical building of the monumental compound in Piazza Palazzo in the historical center of the town of Cagliari (Italy). Three types of carbonate building materials have been used historically to construct ancient monuments in the historical center of Cagliari, which in order of increasing hardness are: Pietra Cantone, Tramezzario and Pietra Forte. Our methodology begins with an accurate microscopic examination of petrographic thin sections and scanning electron microscope (SEM) analysis of the above carbonate materials in order to identify their textural characteristics and especially the nature and distribution of their porosity. Other rock properties such as wet and dry bulk density were calculated from saturated and dry mass and volume respectively. In a second step we used a Leica HDS-6200 terrestrial laser scanner (TLS) to 3D model some building of the studied monumental compound (Piazza Palazzo). Surface geometrical anomalies have been modeled for the most interesting architectural elements, such as a Pietra Cantone portal in Late Gothic style inside the Antico Palazzo di Città, a historical building that hosts the civic museum bearing the same name. Since TLS technology is characterized by high productivity but is unable to investigate the inner parts of the studied materials, a third step of our procedure was complemented by several ultrasonic in situ and laboratory tests in the 54kHz - 82kHz range. The ultrasonic parameters, especially longitudinal and transversal velocities, can be measured very accurately and correlated with various material properties with reasonable confidence. This task has two objectives: one is to compare the petrographical and petrophysical rock properties with the elastic-dynamic ones, while the other is to compare TLS geometrical anomalies with the anomalies of the velocity field detected with ultrasonic methodology, which is very effective in detecting altered and/or damaged zones both on the surface and inside the building materials of architectural elements. Analogies between TLS surface geometrical anomalies and the ultrasonic velocity field are evident at the surface and in shallow parts of the investigated architectural elements, as in the mentioned Pietra Cantone ancient portal. This study illustrates how the integrated application of TLS technology and the ultrasonic method contributes in overcoming ambiguities in the interpretation of the individual dataset. Therefore the methodology proposed in this study has proved to be effective in giving useful indications aimed at formulating a recovery and preservation plan for a monumental structure and to monitor its conservation status in time.

Description: Copernicus Meetings

Description: Published

Description: Vienna | Austria | 17–22 April 2016

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: The selection of a CO2 geologic storage site requires the choice of a study site suitable for the characterization in order to create a robust experimental database especially regarding the spatial petrophysical heterogeneities and elasto-mechanical properties of the rocks that make up a potential caprock-reservoir system. In our study the petrophysical and elasto-mechanical characterization began in a previously well drilled area in the northern part of the Sulcis coal basin (Nuraxi Figus area - SW Sardinia - Italy) where crucial geologic data were recovered from high-quality samples from stratigraphic wells and from mining galleries. The basin represents one of the most important Italian carbon reserves characterized by a great mining potential. In the study area, the Middle Eocene - Lower Oligocene Cixerri Fm. made up of terrigeneous continental rocks and the Upper Thanetian - Lower Ypresian Miliolitico Carbonate Complex in the Sulcis coal basin have been identified respectively as potential caprock and reservoir for CO2 storage. Petrophysical and geophysical investigations were carried out by a great number of laboratory tests on the core samples and in situ measurements on a mining gallery in order to characterize the potential caprock-reservoir system and to substantially reduce geologic uncertainty in the storage site characterization and in the geological and numerical modelling for the evaluation of CO2 storage capacity. In order to better define the spatial distribution of the petrophysical heterogeneity, the seismic responses from the caprock-reservoir system formations were also analysed and correlated with the petrophysical and elasto-mechanical properties In a second step of this work, we also analysed the tectonic stability of the study area by the integrated application of remote-sensing monitoring spatial geodetic techniques. In particular, the global positioning system (GPS) and interferometric synthetic aperture radar (inSAR) were considered useful tools to test the tectonic stability of the storage site. We computed the crustal strain rate of the Sulcis basin starting from the horizontal and vertical velocities detected by applying the two above remote sensing techniques. At the beginning we calculated the Eurasian intra-plate velocity and position time series of some good quality permanent GPS sites present in the study area. We then compared the computed GPS height variation of these sites with the line of sight (LOS) component of InSAR permanent scatters time series detected with the aid of the small baseline (SBAS) method and located closer to the GPS stations. The horizontal components show insignificant residual intra-plate velocities ranging between 0-1 mm/y, while the vertical velocities are comprised between 0 to 2 mm/y, testifying to the stability of the area. The same remote techniques mentioned above can be used during and after the injection of the CO2 to monitor the storage site. This remote monitoring option can be effective, cheap and repeatable.

Description: Copernicus Meetings

Description: Published

Description: Vienna | Austria | 17–22 April 2016

Description: 7A. Geofisica per il monitoraggio ambientale

Description: In March/April 2020 the Italian government drastically reduced vehicle traffic and interrupted all non-essential industrial activities over the entire national territory. Italy thus became the first country in the world, with the exception of Hubei, to enact lockdown measures as a consequence of the COVID-19 outbreak and the need to contain it. Italy is also a seismically active area, and as such is monitored by a dense permanent network of seismic stations. We analyse continuous seismic data from many stations in northern and central Italy, and quantify the impact of the lockdown on seismic ambient noise, as a function of time and location. We find that the lockdown reduces ambient noise significantly in the 1–10 Hz frequency range; because natural sources of seismic noise are not affected by the lockdown, the seismic signature of anthropic noise can be characterised with unprecedented clarity, by simply comparing the signal recorded before and after the lockdown. Our results correlate well with independent evaluations of the impact of the lockdown (e.g., cell phone displacements), and we submit that ambient-noise seismology is a useful tool to monitor containment measures such as the coronavirus lockdowns.

Description: European Union Horizon 2020 Research and Innovation Programme, grant agreements 802777-MONIFAULTS.

Description: Published

Description: 9404

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: Quantifying subaerial fluxes of CO2 is key in a diverse range of applications, including carbon capture and storage sites, emissions from urban areas and industrial sites such as oil refineries, or forecasting volcanic eruptions. All of these have one thing in common: they represent spatially extended sources with a generally unknown spatial distribution of CO2 concentration. The conventional approach to measure CO2 fluxes is to first measure CO2 concentrations in situ at several points and estimate 2D CO2 concentration profiles. Along with the plume transport speed, the concentration profiles can then be used to compute CO2 fluxes. Active remote sensing of CO2 concentrations offers crucial advantages over in situ probing, including a spatially comprehensive measurement, a safe measurement distance, and faster acquisition, which enables real-time monitoring. This makes it also a viable complement or alternative to fence-line monitoring at industrial sites. In the last few years, technology has advanced sufficiently to allow for the realization of robust and portable remote sensing platforms that are relatively inexpensive and user friendly. Within the frameworks of the European Research Council CO2Volc and proof-of-concept CarbSens projects, such a remote sensing platform has been developed to probe CO2 emissions. It may be operated from a fixed location on the ground, from moving platforms (e.g., cars), or be airborne. The kit was used to probe CO2 concentrations and perform a feasibility test to obtain a tomographic 2D image of the subaerial CO2 distribution inside the Solfatara crater, part of arguably the most hazardous volcano in the world: Campi Flegrei near Naples, Italy. The methodology could be applied directly to industrial applications, including quantifying fugitive CO2 at storage and industrial sites. An unmanned aerial vehicle portable kit is envisaged.

Description: Published

Description: 306-313

Description: 4V. Processi pre-eruttivi

Description: N/A or not JCR

Description: A critical point in the analysis of ground dis- placement time series, as those recorded by space geodetic techniques, is the development of data-driven methods that allow the different sources of deformation to be discerned and characterized in the space and time domains. Multivariate statistic includes several approaches that can be considered as a part of data-driven methods. A widely used technique is the principal component analysis (PCA), which allows us to reduce the dimensionality of the data space while maintain- ing most of the variance of the dataset explained. However, PCA does not perform well in finding the solution to the so-called blind source separation (BSS) problem, i.e., in recovering and separating the original sources that gener- ate the observed data. This is mainly due to the fact that PCA minimizes the misfit calculated using an L 2 norm (χ 2 ), look- ing for a new Euclidean space where the projected data are uncorrelated. The independent component analysis (ICA) is a popular technique adopted to approach the BSS problem. However, the independence condition is not easy to impose, and it is often necessary to introduce some approximations. To work around this problem, we test the use of a modi- fied variational Bayesian ICA (vbICA) method to recover the multiple sources of ground deformation even in the presence of missing data. The vbICA method models the probability density function (pdf) of each source signal using a mix of Gaussian distributions, allowing for more flexibility in the description of the pdf of the sources with respect to standard ICA, and giving a more reliable estimate of them. Here we present its application to synthetic global positioning system (GPS) position time series, generated by simulating deforma- tion near an active fault, including inter-seismic, co-seismic, and post-seismic signals, plus seasonal signals and noise, and an additional time-dependent volcanic source. We evaluate the ability of the PCA and ICA decomposition techniques in explaining the data and in recovering the original (known) sources. Using the same number of components, we find that the vbICA method fits the data almost as well as a PCA method, since the χ 2 increase is less than 10 % the value cal- culated using a PCA decomposition. Unlike PCA, the vbICA algorithm is found to correctly separate the sources if the correlation of the dataset is low (〈0.67) and the geodetic network is sufficiently dense (ten continuous GPS stations within a box of side equal to two times the locking depth of a fault where an earthquake of Mw 〉 6 occurred). We also provide a cookbook for the use of the vbICA algorithm in analyses of position time series for tectonic and non-tectonic applications.

Description: Published

Description: 323–341

Description: 1T. Struttura della Terra

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: The elevation of an orogenic belt is commonly related to crustal/lithosphere thickening. Here, we discuss the Apennines as an example to show that topography at a plate margin may be controlled not only by isostatic adjustment but also by dynamic, mantle-driven processes. Using recent structural constraints for the crust and mantle we find that the expected crustal isostatic component explains only a fraction of the topography of the belt, indicating positive residual topography in the central Apennines and negative residual topography in the northern Apennines and Calabria. The trend of the residual topography matches the mantle flow induced dynamic topography estimated from regional tomography models. We infer that a large fraction of the Apennines topography is related to mantle dynamics, producing relative upwellings in the central Apennines and downwellings in the northern Apennines and Calabria where subduction is still ongoing. Comparison between geodetic and geological data on vertical motions indicates that this dynamic process started in the early Pleistocene and the resulting uplift appears related to the formation and enlargement of a slab window below the central Apennines. The case of the Apennines shows that at convergent margins the elevation of a mountain belt may be significantly different from that predicted solely by crustal isostasy and that a large fraction of the elevation and its rate of change are dynamically controlled by mantle convection.

Description: Published

Description: 163-174

Description: 1T. Struttura della Terra

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Gli analisti del BSI hanno revisionato tutti gli eventi di magnitudo M≥1.5, localizzati dal 1 MAGGIO AL 31 AGOSTO 2019. I parametri dei terremoti di magnitudo inferiore a tale soglia di revisione, sono quelli calcolati in tempo reale, nella sala di sorveglianza sismica di Roma.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: 4IT. Banche dati

Description: DAL 1 SETTEMBRE AL 31 DICEMBRE 2019 la revisione della sismicità fatta dagli analisti del BSI ha riguardato tutti gli eventi di magnitudo M≥1.5. I parametri dei terremoti di magnitudo inferiore a tale soglia di revisione, sono quelli calcolati in tempo reale, nella sala di sorveglianza sismica di Roma. Tutti gli eventi con M≥3.5, e pochi altri di particolare interesse (vedi Marchetti et al., 2016, DOI: 10.4401/ag-7169), sono stati rianalizzati dagli analisti del BSI, contestualmente al loro accadimento.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: 4IT. Banche dati

Description: Nel periodo che va dal 1 gennaio al 30 aprile 2019, gli analisti del BSI hanno revisionato tutti gli eventi di magnitudo M≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia di revisione sono stati calcolati in tempo reale, nella sala di sorveglianza sismica di Roma.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: 4IT. Banche dati

Description: Gli analisti del BSI hanno revisionato tutti gli eventi di magnitudo M≥1.5, localizzati dal 1 settembre al 31 dicembre 2018. I parametri dei terremoti di magnitudo inferiore a tale soglia di revisione, sono quelli calcolati in tempo reale, nella sala di sorveglianza sismica di Roma.

Description: Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione Civile

Description: Published

Description: 4IT. Banche dati

Description: This article has been accepted for publication in Geophysical Journal International ©: The Authors 2019. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Uploaded in accordance with the publisher's self-archiving policy.

Description: We investigate the temporal changes of crustal velocity associated to the seismic sequence of 2016–2017, which struck central Italy with a series of moderate to large earthquakes. We cross- correlate continuous recordings of 2 yr of ambient seismic noise from a network of 28 stations within a radius of 90 km around Amatrice town. We then map the spatio-temporal evolution of the velocity perturbations under the effect of subsequent earthquakes. Coinciding with each of the three main shocks of the sequence we observe a sudden drop of seismic velocity which tends to quickly recover in the short term. After the end of the strongest activity of the sequence, the coseismic velocity changes display gradual healing towards pre-earthquake conditions following a quasi-linear trend, such that by the end of 2017 about 75 per cent of the perturbation is recovered. The spatial distribution of the velocity drop fluctuates with time, and the area that shows the most intense variations beyond the ruptured fault system elongates in the NE direction. This zone roughly corresponds to a region of foredeep sedimentary deposits consisting of highly hydrated and porous sandstones, which respond to the passage of seismic waves with increased pore pressure and crack number, leading to a reduction of the effective relative velocity.

Description: Published

Description: 2165–2173

Description: 7T. Variazioni delle caratteristiche crostali e precursori sismici

Description: JCR Journal

Description: Stromboli is famous for its persistent volcanic activity consisting of periodic discrete explosions alternating with lava effusion and more violent explosions. This paper presents a detailed reconstruction of the geological history of Stromboli and description of the characteristics and distribution of the volcanic units and structural features. Six main growth stages (Eruptive Epochs 1–6), in addition to the c. 200 ka activity of Strombolicchio, are recognized between c. 85 ka and the present day, displaying a magma composition ranging from calc-alkaline to potassic series which usually varies with changing Eruptive Epochs. The Epochs are subdivided into sequences of eruptions and characterized by dominant central-vent summit activity with episodic phases of flank activity along fissures and eccentric vents. The activity was repeatedly interrupted by erosional and destructive phases driven by recurrent vertical caldera-type (cc1–5) and sector (and flank) collapses (sc1–7) and generally associated with significant quiescences. The different serial character of the Stromboli rocks is associated with largely variable trace element contents and isotope ratios. These petrochemical characteristics together with our new stratigraphy indicate that magmas, generated in a heterogeneous mantle wedge, underwent complex differentiation processes during their ascent. Magmas are characterized by polybaric evolution residing in small magma reservoirs that are alternatively tapped by the different collapses.

Description: Published

Description: 397-471

Description: 1V. Storia eruttiva

Description: Samples of efflorescences and encrustations of hydrothermal origin were collected at Sousaki (Greece) and analysed for their mineralogical (XRD) and chemical composition. Solutions obtained both from mineralization with HNO3 and from leaching with deionised water were analysed for major (ICP-OES), minor and trace metals (ICP-MS) and sulfate contents (IC). Results evidence the dependence of the chemical and mineralogical composition on micro-environmental conditions i.e. humidity, oxygen-rich or -poor environment, exposed or sheltered from meteoric agents. In fact, the presence of highly soluble sulfate minerals with elevated contents of many metals (e.g. Mg, Al, Fe, Mn, Cr, Ni, etc.) further underscores the important influence of hydrothermal activity on elements' mobility, whilst the sometimes very high concentrations in toxic elements like Al, Cr, Ni suggest also possible environmental impacts.

Description: Published

Description: 107121

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: Highlights -He isotopic R/Ra of emitted gas decreases moving away from Albani Hills volcano -Total soil flux of endogenous CO2 at Lavinio-Tor Caldara is estimated to 20 ton/day -Tor Caldara gas has the highest H2S content (up to 6.3 vol.%) of central Italy -Repetition of soil CO2 flux survey shows that flux increases during earthquakes -Gas air concentration monitoring shows that H2S is the killer gas of small animals

Description: Gas hazard was evaluated at Lavinio-Tor Caldara, the southernmost gas-discharging zone of the quiescent Albani Hills volcano in central Italy. Also this zone, like the other gas discharges of this volcanic complex, is located above a structural high of the buried Mesozoic carbonate basement, which represents the main reservoir for gas rising from depth. All extensional faults affecting the carbonates are leaking pathways along which gas may rise to the surface creating hazardous conditions. Gas is dominated by CO2 (〉90 vol.%) and the second component at Lavinio-Tor Caldara is H2S that displays the highest content (4.0-6.3 vol.%) of all gas manifestations of the Rome region. This H2S enrichment corresponds to a marked decrease in 3He/4He (R/Ra) isotopic ratio suggesting that gas was contaminated in an upper crustal environment. The main gas discharge occurs at the natural reserve of Tor Caldara, in zones where past sulphur mining excavations removed the surficial impervious cover, or along a ditch. Comparison of the results of four soil CO2 flux surveys carried out in 2005-2018 at Miniera Grande within Tor Caldara, indicates that the highest soil CO2 release occurs shortly after local earthquakes. Continuous monitoring of CO2 and H2S air concentration and of wind speed has been carried out for four months in twelve anomalous gas realising sites of Tor Caldara. Results indicate that only H2S reaches lethal concentration (〉250 ppm) near the soil in no wind nights, explaining the presence of small dead animals. At Lavinio, the main soil gas release occurs near old water wells that likely produced a gas blowout during drilling. A total release of over 20 tons/day from 2.93 km2 of gas of endogenous origin, has been estimated for the Lavinio-Tor Caldara area by a detailed soil CO2 flux survey (2,572 measurement points over an area of 3.65 km2). The main structural lineaments of the area have N-S and W-E directions, but also NE-SW and NW-SE directions are well represented. Some sectors of the investigated area are exposed to a severe gas hazard for people and animals and precautionary measures should be adopted.

Description: Published

Description: 106985

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: This report summarizes the seismicity in Switzerland and surrounding regions in the years 2015 and 2016. In 2015, the Swiss Seismological Service detected and located 735 earthquakes in the region under consideration. With a total of 20 earthquakes of magnitude ML C 2.5, the seismic activity of potentially felt events in 2015 was close to the average of 23 earthquakes over the previous 40 years. Seismic activity was above average in 2016 with 872 located earthquakes of which 31 events had ML C 2.5. The strongest event in the analyzed period was the ML 4.1 Salgesch earthquake, which occurred northeast of Sierre (VS) in October 2016. The event was felt in large parts of Switzerland and had a maximum intensity of V. Derived focal mechanisms and relative hypocenter relocations of aftershocks image a SSE dipping reverse fault, which likely also hosted an ML 3.9 earthquake in 2003. Another remarkable earthquake sequence in the Valais occurred close to Sion with four felt events (ML 2.7–3.2) in 2015/16. We associate this sequence with a system of WNW-ESE striking fault segments north of the Rhoˆne valley. Similarities with a sequence in 2011, which was located about 10 km to the NE, suggest the existence of an en-echelon system of basement faults accommodating dextral slip along the Rhoˆne-Simplon line in this area. Another exceptional earthquake sequence occurred close to Singen (Germany) in November 2016. Relocated hypocenters and focal mechanisms image a SW dipping transtensional fault segment, which is likely associated with a branch of the Hegau-Bodensee Graben. On the western boundary of this graben, micro-earthquakes close to Schlattingen (TG) in 2015/16 are possibly related to a NE dipping branch of the Neuhausen Fault. Other cases of earthquakes felt by the public during 2015/16 include earthquakes in the region of Biel, Vallorcine, Solothurn, and Savognin.

Description: SwissEnergy (http:// www.energieschweiz.ch) and the Swiss Federal Office of Energy for the financial support of project GEOBEST-CH; Swiss Competence Center for Energy Research—Supply of Electricity (http://www.sccer-soe.ch); Swiss-AlpArray SINERGIA project CRSII2_154434/1 by the Swiss National Science Foundation (SNSF)

Description: Published

Description: 221–244

Description: 2T. Sorgente Sismica

Description: 1IT. Reti di monitoraggio

Description: 5IT. Osservatori

Description: JCR Journal

Description: We derive a unifying formulation, reliable at all scales, linking Anderson’s faulting theory with the earthquake size-distribution, whose exponent is known as the b-value. Anderson’s theory, introduced in 1905, related fault orientation to stress conditions. Independently, laboratory measurements on acoustic emissions have established that the applied differential stress controls their b-value. Our global survey revealed that observed spatial variations of bare controlled by different stress regimes, generally being lower in compressional (subduction trenches and continental collisional systems) and higher in extensional regimes (oceanic ridges). This confirmed previous observations that the b-value depends on the rake angle of focal mechanisms. Using a new plunge/dip-angles-based b-value analysis, we also identified further systematic influences of faulting geometry: steep normal faults (also typical of the oldest subduction zones) experience the highest proportion of smaller events, while low-angle thrust faults (typical of youngest subduction zones) undergo proportionally larger, more hazardous, events, differently from what would be expected by only allowing for rake-angle dependency. To date, however, no physical model has ever been proposed to explain how earthquakes size-distribution, differential stress and faulting styles relate to each other. Here, we propose and analytically derive a unifying formulation for describing how fault orientation and differential stresses determine b-value. Our formulation confirms that b-values decay linearly with increasing differential stress, but it also predicts a different dip-dependent modulation according to the tectonic environment, opening up new ways of assessing a region’s seismic hazard.

Description: Published

Description: 115791

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: The Calabrian subduction zone is one of the narrowest arcs on Earth and a key area to understand the geodynamic evolution of the Mediterranean and other marginal seas. Here in the Ionian Sea, the African plate subducts beneath Eurasia. Imaging the boundary between the downgoing slab and the upper plate along the Calabrian subduction zone is important for assessing the potential of the subduction zone to generate mega‐thrust earthquakes and was the main objective of this study. Here we present and analyze the results from a 380 km long, wide‐angle seismic profile spanning the complete subduction zone, from the deep Ionian Basin and the accretionary wedge to NE Sicily, with additional constraints offered by 3‐D Gravity modeling and the analysis of earthquake hypocenters. The velocity model for the wide‐angle seismic profile images thin oceanic crust throughout the basin.

Description: Published

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: A systematic decay of the aftershock rate over time is one of the most fundamental empirical laws in Earth science. However, the equally fundamental effect of a mainshock on the size distribution of subsequent earthquakes has still not been quantified today and is therefore not used in earthquake hazard assessment. We apply a stacking approach to well-recorded earthquake sequences to extract this effect. Immediately after a mainshock, the mean size distribution of events, or b-value, increases by 20-30%, considerably decreasing the chance of subsequent larger events. This increase is strongest in the immediate vicinity of the mainshock, decreasing rapidly with distance but only gradually over time. We present a model that explains these observations as a consequence of the stress changes in the surrounding area caused by the mainshocks slip. Our results have substantial implications for how seismic risk during earthquake sequences is assessed.

Description: Published

Description: 13277–13287

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: JCR Journal

Description: KnowRISK (Know your city, Reduce seISmic risK through non-structural elements) is a European project that addresses prevention measures to reduce non-structural damage caused by earthquakes. It is built on risk communication and takes action on pilot areas of the three participating countries: Portugal, Iceland, and Italy. The setting up of risk communication strategies in the project stands on the understanding local communities fragility, on their direct engagement, and on a holistic approach to vulnerability. The level of relevance of seismic compared to other hazards, the understanding, the memory of past disasters are indicators that affect the way a risk is perceived and preventive measures are taken. Similarly, the level of education, wealth, exposure to other, social, risks are aggravation parameters in risk computation to be accounted for when we communicate risk. Strategies for risk communication in KnowRISK rely on schools and citizen’s engagement, citizen’s science activities, tools for raising awareness.

Description: Published

Description: 413-427

Description: 2TM. Divulgazione Scientifica

Description: he study of coseismic surface ruptures provides insights into earthquakes dynamics and fault growth processes. We analyze the surface faulting related to the seismic sequence that hit central Italy in 2016–2017, focusing on the ruptures caused by 30 October 2016 Mw 6.5 Norcia earthquake. They are located on the NW trending normal fault splays of the Mount Vettore-Mount Bove fault system (VBFS), forming a fracture network made of hundreds of strands striking N135–160°. The surface rupture length for this event is ~22 km, with average surface slip of ~0.44 m and peak of ~2.10 m. The collected coseismic slip vectors yield an average N233° trending extension, consistent with the local structural setting and seismological data. Surface slip displays cumulative frequency-size distributions of rupture length and offset that follow power law and exponential scaling over 2 orders of magnitude, respectively. We observe strain localization on a few major fault splays of the VBFS, causing a markedly asymmetric along-strike slip profile, with a high gradient to the southeast. The ~5-km-long Cordone del Vettore fault accounts for 40% of the overall coseismic surface slip. We infer that the heterogeneous slip at depth, coupled with the highly segmented nature of the VBFS and its interference with thrusts and adjacent active normal faults, has control over the pattern of surface faulting. For the Norcia earthquake, a robust scaling of surface slip area with rupture length accounts for extreme slip peaks over relatively short ruptures, which we envisage may be typical of the VBFS long- term growth.

Description: Published

Description: 3378-3410

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: We conducted paleoseismic studies along the Montereale fault system (MFS; central Italy). The MFS shows geomorphological evidence of Late Quaternary activity and falls within the highest seismic hazard zone of central Apennines, between the epicentral areas of two recent earthquake sequences: 2009 L’Aquila and 2016–2017 central Italy. We excavated two trenches along the San Giovanni fault splay of the system, one intercepting the N140° striking bedrock main fault plane and the other cutting two subparallel fault scarps on the colluvial/alluvial deposits on the fault hanging wall. Excavations revealed repeated fault reactivation with surface faulting in prehistorical and historical times. We recognized and dated seven events in the last 26 kyr. The most recent ground-rupturing event (evb1) possibly occurred 650–1,820 AD, consistent with one of the three main shocks that struck the area in 1,703 AD. A previous event (evb2) occurred between 5,330 BC and 730 BC, while older events occurred at 6,590–5,440 BC (evb3), 9,770–6,630 BC (evb4), and 16,860–13,480 BC (evb5). We documented two older displacement events (evb7 and evb6) between 23,780 BC and 16,850 BC. The minimum vertical slip rate at the trench site in the last 28–24 kyr is 0.3–0.4 mm/year. The inferred average recurrence interval for surface-faulting events along the MFS is no longer than ~4 kyr. Based on the surface fault length ranging between 12 and 20 km, earthquakes with ≥M 6.0 are possible for the MFS. The MFS is an independent earthquake source, and its paleoseismic data are fully comparable with those known for faults in central Apennines.

Description: Published

Description: 2758-2776

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: JCR Journal