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Assessing long-term tephra fallout hazard in southern Italy from Neapolitan volcanoes
No full textNowadays, modeling of tephra fallout hazard is coupled with probabilistic analysis that takes into account the natural variability of the volcanic phenomena in terms of eruption probability, eruption sizes, vent position, and meteorological conditions. In this framework, we present a prototypal methodology to carry out the long-term tephra fallout hazard assessment in southern Italy from the active Neapolitan volcanoes: Somma–Vesuvius, Campi Flegrei, and Ischia. The FALL3D model (v.8.0) has been used to run thousands of numerical simulations (1500 per eruption size class), considering the ECMWF ERA5 meteorological dataset over the last 30 years. The output in terms of tephra ground load has been processed within a new workflow for large-scale, high resolution volcanic hazard assessment, relying on a Bayesian procedure, in order to provide the mean annual frequency with which the tephra load at the ground exceeds given critical thresholds at a target site within a 50-year exposure time. Our results are expressed in terms of absolute mean hazard maps considering different levels of aggregation, from the impact of each volcanic source and eruption size class to the quantification of the total hazard. This work provides for the first time, a multi-volcano probabilistic hazard assessment posed by tephra fallout, comparable with those used for seismic phenomena and other natural disasters. This methodology can be applied to any other volcanic areas or over different exposure times, allowing researchers to account for the eruptive history of the target volcanoes that, when available, could include the occurrence of less frequent large eruptions, representing critical elements for risk evaluations.Published2289–23116V. Pericolosità vulcanica e contributi alla stima del rischioJCR Journa
The set up of the “UNO” Project relational database for Stromboli volcano
No full textActive volcanoes are complex, poorly predictable systems that can pose a threat to humans and their infrastructures. As such, it is important to improve as much as possible the understanding of their behavior. The Stromboli volcano, in Italy, is one of the most active volcanoes in the world, and its almost persistent activity is documented since centuries. The persistent background activity is sometimes interrupted by much more energetic, dangerous episodes. The Istituto Nazionale di Geofisica e Vulcanologia (Italy) set up the interdisciplinary “UNO” project, aimed to understand when the Stromboli volcano is about to switch from the ordinary to the extraordinary activity. The UNO project includes an outstanding variety of research activities, such as sampling in the field, the modeling of Stromboli topography from ALS technique and satellite data, the 3D numerical simulations of ballistic trajectories, or the set up of an ultrasonic microphones system. Key to the success of the project is the collection of integrated high spatial and temporal resolution data and their joint analyses in a shared relational database. We present here the simplified logical model of such database, focusing on the identification of entities and their relationships.PublishedVienna, AustriaOSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciOSV1: Verso la previsione dei fenomeni vulcanici pericolos
The Explosive Activity of the 2021 Tajogaite Eruption (La Palma, Canary Islands, Spain)
No full textThe explosive activity of the 2021 Tajogaite eruption eludes pigeonholing into well-defined eruption styles, with a variety of pyroclast ejection modes occurring both alternately and simultaneously at multiple vents. Visually, we defined four endmembers of explosive activity, referred to as fountaining, spattering, ash-poor jets and ash-rich jets. To capture the physical parameters of these activities, we deployed a camera array including one high-speed camera and three high-definition cameras in two field campaigns. Transitions between and fluctuations within activity occurred at the time scale of minutes to hours, likely driven by the same shallow conduit and vent processes controlling Strombolian activity at other volcanoes, but at higher gas and magma fluxes. From a physical standpoint, mean pyroclast rise velocity ranged 5–50 m/s, maximum ejection velocity 10–220 m/s, and sub-second mass flux of lapilli to bomb-sized pyroclasts at the vent 0.2–200 × 103 kg/s. The largest mass flux occurred during fountaining, which contributed by far more than other activities to cone building. All explosive activity exhibited well-defined pyroclast ejection pulses, and we found a positive correlation between the occurrence rate of ejection pulses and maximum pyroclast ejection velocity. Despite orders of magnitude variations, physical parameters shift gradually with no boundary from one activity endmember to another. As such, attributing this explosive activity specifically to any currently defined style variations is arbitrary and potentially misleading. The highly variable explosive activity of the Tajogaite eruption recalls previous definitions of violent Strombolian eruptions, an eruption style whose pyroclast ejection dynamics, however, were so far largely undefined.financially supported by the projects VOLRISKMAC (MAC/3.5b/124) and VOLRISKMAC II (MAC2/3.5b/328), financed by the Program INTERREG V A Spain-Portugal MAC 2014–2020 of the European Commission; CUMBRE VIEJA EMERGENCIA, financed by the Science and Innovation Ministry, Spanish Government; TFASSISTANCE, financed by the Cabildo Insular de Tenerife, and LPVOLCANO, financed by the Cabildo Insular de La Palma.Publishede2023GC010946OSV1: Verso la previsione dei fenomeni vulcanici pericolosiOSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciOSV3: Sviluppo di nuovi sistemi osservazionali e di analisi ad alta sensibilitàOSV4: Preparazione alle crisi vulcanicheJCR Journa
Geology of the lower Belice River valley, epicentral area of the M > 5 1968 seismic sequence (south-western Sicily, Italy)
No full textWe present a new 1:25,000-scale geological map of the lower Belice River valley, the area struck by the M > 5.0 devastating 1968 seismic sequence, whose seismic source and seismotectonic framework are still controversial. The map, utilizing dating methods and traditional field survey approaches integrated by high-resolution topography, provides an unprecedented detail and precision on the spatial distribution and on the compressional growth geometries of the prominent sedimentary sequence. This map, supported by the first recognition of an on-shore Chibanian-Calabrian deposition and by identifying a flight of marine terraces, offers new insights on the long-lasting syn-depositional tectonic forces up to late-Pleistocene-Holocene times. Such tectonic forces may take part in the regional ongoing deformational phase, prompting detailed studies on the potential seismic sources affecting the area.Published2242725OST3 Vicino alla fagliaJCR Journa
X-ray computed microtomography revealing the effects of volcanic, alteration, and burial processes on the pore structure of rocks from unconventional reservoirs (Songliao Basin, NE China)
No full textThe pore structure and storage volume of rocks are crucial parameters to evaluate the favorability of hydrocarbon reservoirs. The unconventional volcanic reservoirs in the Songliao Basin (NE China) include lava and pyroclastics of different composition. Here we apply the X-ray computed microtomography (micro-CT) to reconstruct the 3D pore space of selected samples (basaltic lava, rhyolitic lava and rhyolitic pyroclastics) at depths between 2283 and 3757 m. We reconstruct the morphology and size distribution of the pores. The pore structure records the effects of superimposed volcanic, alteration, and compaction-burial processes. This latter process produces fractures in the rhyolitic pyroclastic rocks. The basaltic lavas have larger, connected pores filled by alteration minerals with a prolate shape, and unconnected, smaller, blade-like, empty pores. The hydrothermal alteration reduces the porosity and the rock is impermeable being the smaller voids unconnected. The basaltic lavas are good cap rocks but very poor reservoir rocks. The rhyolitic lava flows and pyroclastics, some of which placed in the gas zone of the Songliao reservoirs, show prevailing interconnected fractures due to burial processes and minor pores around crystals formed by syn-eruptive heterogeneous gas nucleation. The pore connectivity is ensured by the fractures and the permeability may be high, also depending on the volume, more than on the number, of the pores. Rhyolites may be good reservoir 2 rocks. We search for possible relationships between porosity and permeability and do not find a clear relation between these two parameters as well as between depth and permeability. Although our analysis is valid within a length scale between about 20 μm and 1 cm, the methodological approach used here can be extended to other reservoirs to study the evolution of the pore systems as a function of the different processes affecting the volcanic rocks.Published211781JCR Journa
The intra-orogenic normal Lakes Fault (Sila, Calabria, southern Italy): new insights from geodetic and seismological data
No full textThe Calabrian Orogenic Arc (COA) is affected by active extensional and strike-slip tectonics as documented by the presence of N-S and NE-SW trending intra-montane basins bordered by faults, whose slip has caused many destructive earthquakes during the last millennium. By focusing on the central sector of the COA (Sila Massif) through the analysis of new seismological and geodetic datasets, we observed some relevant differences (e.g., seismic activity and hypocentral depths, faulting style, geodetic strain, vertical rates) between its western and eastern sector. The transition between the two sectors occurs in the area of the Lakes Fault, a NW-SE striking and west-dipping fault indicated as the causative source of the 8 June 1638 M 6.8 earthquake. By modelling the available geodetic data, we inferred a dislocation plane whose geometry and kinematics (a prevalent dip-slip component coupled with minor left-lateral strike-slip) is compatible with the real fault reported in literature. This fault only accounts for a small amount of the deformation across northern COA and divides the seismically more active western sector from its eastern counterpart with appreciable geodetic strain and moderate seismicity. Results are encouraging and a similar approach can help in other regions where surface evidence of active faults are rare or non-existing and field geological investigations are hence difficult.Published384-397OST3 Vicino alla fagliaJCR Journa
A Case Study of Multidisciplinary Surface Faulting Assessment in the Urbanized Fucino Basin, Italy
No full textThe occurrence of coseismic surface ruptures along fault traces in urbanised areas creates a serious hazard to the vulnerability of man-made manufactures. In order to mitigate such hazard, it is necessary to investigate the geometry, the activity and the capability of faults located close to urbanised areas. This paper presents a case study of the investigation of capable faults within a sensitive area in Italy that is characterized by a high density of population and industrial activities, high levels of seismicity and the presence of faults proven to be capable of rupturing the surface during medium-to-large earthquakes. We focused on the Luco fault (Fucino basin, Central Italy), which previous studies have suggested to cross the industrial district of the town of Avezzano. We present a multidisciplinary approach, consisting of Electrical Resistivity Tomography surveys, continuous-coring boreholes and paleoseismological trenches, aimed at accurately constraining the trace of the Luco fault and documenting the associated fault displacement. This allowed us to constrain the geometry of the Luco fault and to assess the
associated fault displacement hazard. We suggest that the proposed methodology represents a pilot study for further investigations of capable faults in the Italian and other similar seismotectonic contexts.Published104-121OST3 Vicino alla fagliaJCR Journa
Mt. Etna Tilt Signals Associated with February 6, 2023, M=7.8 and M=7.5 Turkey Earthquakes
No full textOn February 6, 2023, at 01 : 17 UTC, a M = 7 8 earthquake struck the southern area of Turkey near Gaziantep town and was
followed by a second earthquake of M = 7 5 at 10 : 24 UTC with the epicenter in Elbistan city. Both events were associated with
the Anatolian Fault System and have claimed over 50,000 victims, as reported by the Disaster and Emergency Management
Authority, and caused serious damage in the regions of southern Turkey and northern Syria. Seismic waves related to strong
Turkey earthquakes have been recorded both by seismic stations throughout the globe and on other devices such as the ground
deformation (GNSS, strainmeters, or tiltmeters) networks. In this paper, we show and analyze the earthquake signals recorded
by bore-hole tilt stations that monitor seismic and volcanic activities at Mt. Etna. Tilt stations showed very large variations,
despite their distance from the epicenter (approximately 1950 km) with a period between 10 and 25 seconds. We compared tilt
and seismic data for a co–located station evidencing a very similar waveform that highlight how tiltmeters respond to
translational acceleration rather than ground tilt during a teleseism, suggesting that, for waves with this period, they may
behave as horizontal seismometers. By using these signals, we evidence the different behaviors of two of the most used models
of tiltmeters on volcanoes (Lily and Pinnacle) and how they are useful for instrument calibration.Published9030495OSV3: Sviluppo di nuovi sistemi osservazionali e di analisi ad alta sensibilitàJCR Journa
Plio-Quaternary coastal landscape evolution of north-western Sicily (Italy)
No full textABSTRACTWe present and discuss the results of a geomorphological and geological study aimed at reconstructing the Plio-Quaternary evolution of the NW Sicily coastal belt , a low strain rate region in the central Mediterranean Sea.We performed morphometric and field analysis of Quaternary marine terraces extracting more than 300 shoreline location points subdivided into six orders. The obtained dataset was validate by investigating the morphological changes along topographic profiles and comparing the extracted locations and elevations with the stratigraphic boundaries in the Plio-Quaternary units.We distinguished two contiguous coastal sectors characterized by different paleo-shoreline elevations and Plio-Quaternary evolution, whose estimated uplift rates fit well with the well-known, regional eastward uplift rate increase along the Northern Sicilian continental margin.Obtained results, summarized in a geomorphological map and a morpho-evolutionary model, provide new valuable data to characterize the active deformation processes and the seismotectonic setting in this critical sector of the Africa-Europe plate boundary.Published21598892T. Deformazione crostale attivaJCR Journa
An Innovative Fiber-Optic Hydrophone for Seismology: Testing Detection Capacity for Very Low-Energy Earthquakes
No full textAn innovative fiber-optic hydrophone (FOH) was developed and investigated via an experiment at sea; it is capable of operating at a very low frequency of the seismic spectrum and detecting small magnitude earthquakes. The FOH exploits an optical fiber coil wrapped around a sensitive mandrel in a Michelson interferometric configuration. The FOH operated for about seven days at a water depth of 40 m, in the Campi Flegrei volcanic area (Southern Italy), and a few meters from a well-calibrated PZT hydrophone used as a reference. Thirty-three local earthquakes occurred during the simultaneous operation of the two hydrophones, allowing a straightforward comparison of the recordings. The local earthquakes occurred at an epicentral distance less than 2.5 km from the site of recording, and were estimated to be in the range of magnitude from −0.8 to 2.7. The analysis of the recorded earthquake waveforms in the frequency and time domains allowed retrieving the response function of the FOH in the frequency range from 5 to 70 Hz. The FOH responsivity in terms of acoustic pressure reached about 230 nm/Pa and was flat in the studied frequency range. Due to the high quality of the FOH recordings, this equipment is suitable for applications addressing submarine volcanic activity and the background seismicity of active faults in the ocean.Published33747TM.Sviluppo e Trasferimento TecnologicoJCR Journa