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The role of historical-archaeological sources integrated into the GIS environment with geological and geophysical data in the mitigation of geological risks in some urban areas
No full textNumerous geological risks characterise urban areas, one of the most undervalued of which is the sinkhole risk connected to underground cavities. In the Lazio Region, the subsoil of many beautiful art cities like Rieti and Viterbo is rich in underground cavities, mainly anthropogenic because of their thousand-year history and the geological substrate’s peculiar characteristics. These cavities have very different ages and types, the oldest dates back to the Etruscan and Archaic times. However, their excavation continued uninterrupted during the Roman and Medieval times until the Second World War, when many were readapted as bomb shelters. An interdisciplinary approach that combines geological and geotechnical aspects integrated by geophysics with historical and archaeological data in a GIS project can allow an efficient census of these cavities, defining not only their morphology and their functions but also hypothesising their continuation in unexplored or collapsed traits. Such a census is indispensable to estimate and, therefore, mitigate the sinkhole’s risk and better define risk, including the seismic response of a subsoil articulated and altered by many levels of underground cavities.Published50-57OSA2: Evoluzione climatica: effetti e loro mitigazioneJCR Journa
Airspace Contamination by Volcanic Ash from Sequences of Etna Paroxysms: Coupling the WRF-Chem Dispersion Model with Near-Source L-Band Radar Observations
No full textVolcanic emissions (ash, gas, aerosols) dispersed in the atmosphere during explosive
eruptions generate hazards affecting aviation, human health, air quality, and the environment. We
document for the first time the contamination of airspace by very fine volcanic ash due to sequences
of transient ash plumes from Mount Etna. The atmospheric dispersal of sub-10 m (PM10) ash is
modelled using the WRF-Chem model, coupled online with meteorology and aerosols and offline with
mass eruption rates (MERs) derived from near-vent Doppler radar measurements and inferred plume
altitudes. We analyze two sequences of paroxysms with widely varied volcanological conditions
and contrasted meteorological synoptic patterns in October–December 2013 and on 3–5 December
2015. We analyze the PM10 ash dispersal simulation maps in terms of time-averaged columnar
ash density, concentration at specified flight levels averaged over the entire sequence interval, and
daily average concentration during selected paroxysm days at these flight levels. The very fine
ash from such eruption sequences is shown to easily contaminate the airspace around the volcano
within a radius of about 1000 km in a matter of a few days. Synoptic patterns with relatively weak
tropospheric currents lead to the accumulation of PM10 ash at a regional scale all around Etna. In this
context, closely interspersed paroxysms tend to accumulate very fine ash more diffusively at a lower
troposphere and in stretched ash clouds higher up in the troposphere. Low-pressure, high-winds
weather systems tend to stretch ash clouds into ~100 km wide clouds, forming large-scale vortices
800–1600 km in diameter. Daily average PM10 ash concentrations commonly exceed the aviation
hazard threshold, up to 1000 km downwind from the volcano and up to the upper troposphere for
intense paroxysms. Vertical distributions show ash cloud thicknesses in the range 0.7–3 km, and
PM10 sometimes stagnates at ground level, which represent a potential health hazard.Published3760OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Contemporaneous Thick- and Thin-Skinned Seismotectonics in the External Zagros: The Case of the 2021 Fin Doublet, Iran
No full textIn this work, we propose a geodetic model for the seismic sequence, with doublet earthquakes, that occurred in Bandar Abbas, Iran, in November 2021. A dataset of Sentinel-1 images, processed using the InSAR (Interferometric Synthetic Aperture Radar) technique, was employed to identify the surface deformation caused by the major events of the sequence and to constrain their geometry and kinematics using seismological constraints. A Coulomb stress transfer analysis was also applied to investigate the sequence’s structural evolution in space and time. A linear inversion of the InSAR data provided a non-uniform distribution of slip over the fault planes. We also performed an accurate relocation of foreshocks and aftershocks recorded by locally established seismographs, thereby allowing us to determine the compressional tectonic stress regime affecting the crustal volume. Despite the very short time span of the sequence, our results clearly suggest that distinct blind structures that were previously unknown or only suspected were the causative faults. The first Mw 6.0 earthquake occurred on an NNE-dipping, intermediate-angle, reverse-oblique plane, while the Mw 6.4 earthquake occurred on almost horizontal or very low-angle (SSE-dipping) reverse segments with top-to-the-south kinematics. The former, which cut through and displaced the Pan-African pre-Palaeozoic basement, indicates a thick-skinned tectonic style, while the latter rupture(s), which occurred within the Palaeozoic–Cenozoic sedimentary succession and likely exploited the stratigraphic mechanical discontinuities, clearly depicts a thin-skinned style.Published29812T. Deformazione crostale attivaJCR Journa
Rock deformation vs. radon emission: some constraints from shear stress-controlled experiments
No full textNumerous field and laboratory studies have been conducted to investigate the relationship between radon variation and seismic events, as well as the complex link between radon emission and rock deformation mechanisms. However, a clear understanding of this correspondence and systematic observations of these phenomena are still lacking, and recent experimental studies have yet to yield conclusive results. In this study, we investigate the possible relationships between radon migration dynamics and rock deformation at the micro-scale through laboratory experiments using the SHIVA apparatus under shear stress-controlled conditions and simultaneous high-resolution radon measurements. We studied the behaviour of three different lithologies to show that radon emission varies in response to rock deformation and this variation is highly dependent on the mineralogy and microstructure. This study represents the first attempt to define radon gas as an indicator of transient and rapid rock deformation at the micro-scale.Published16399OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impattoJCR Journa
Transient infiltration tests in pyroclastic soils with double porosity
No full textFallout volcanic deposits of Somma- Vesuvius (Campania, southern Italy), characterized by the presence of layers with contrasting textural and hydraulic properties, are frequently affected by shallow landslides during rainwater infiltration. The soils of the stratigraphic sequence present intra- particle pores, originated by the gases escaped during magma decompression in the volcanic conduit, thus are characterized by double porosity (i.e., intraparticle and interparticle pores), which is expected to affect their hydraulic behaviour, and to play a key role in rainwater infiltration through layered deposits. To understand the effect of double porosity on the hydraulic behaviour of the involved soils, controlled experiments have been carried out in an infiltration column. The experimental apparatus is provided with newly designed non-invasive Time Domain Reflectometry (TDR) probes, not buried in the investigated soil layers so as to minimize disturbance to the flow, allowing water content measurement during vertical flow processes. Specifically, transient flow experiments are carried out through reconstituted specimens of black scoriae and grey pumices, both loose pyroclastic granular soils from fallout deposits of Somma-Vesuvius, featuring double porosity with different pore size distributions, that were estimated by X-ray tomography and Mercury Intrusion Porosimetry. The experimental results highlight the effects of the double porosity and clearly indicate the different behaviour of the two soils during wetting and drying processes, mainly related to the different dimensions of intraparticle pores.Published3327-3342JCR Journa
From Multi-Hazard to Multi-Risk at Mount Etna: Approaches and Strategies of the PANACEA Project
No full textThe management of multiple hazards simultaneously impacting on a territory is a challenge for effective risk mitigation. This is particularly true on active volcanoes like Mt. Etna, characterized by effusive and explosive eruptions, often coupled with an intense seismic activity. This work aims at presenting the approach of the PANACEA project on the treatment of multi-hazards in terms of risk, which requires a common definition of the exposed elements and their vulnerability. Another aspect emerging from the recent and historical volcanic crises at Etna, is the occurrence of cascading effects and the problem of assessing their short-term interactions. Here we present a risk model taking into account a set of sequences of hazardous events which may result from a volcano unrest to possible impacts to some infrastructural elements. The outcomes of the project are intended to be a significant step towards a more comprehensive resilience to volcanic disasters, leading to a more safe society.Published37-406V. Pericolosità vulcanica e contributi alla stima del rischi
The Vanishing Volcanic Geoheritage of a Key Scoria Cone and its Significance in Volcanic Hazard Resilience of the Active Monogenetic Volcanic Field near Al Madinah, Kingdom of Saudi Arabia
No full textFour small scoria cones in the western outskirts of Al Madinah City, the Kingdom
of Saudi Arabia, form a distinct young volcanic landmark. These volcanoes, despite
their very small size, provide one of the most fundamental sources of information
about the early eruption mechanism of rising mafic magma in the context of an
active volcanic field located next to a city with over one million people. An initial
study of the area in 2012–2013 confirmed that these sites had a significant phreatomagmatic
phase in their opening stage, leaving behind characteristic pyroclastic
successions likely to be covered by subsequent eruptive products. The fact that in
this location, unequivocal evidence emerged to show that explosive magma-water
interaction driven eruptions occurred in the largely magmatic (“dry”) explosive
style, and volcanic field evolution confirmed that this site has high geoheritage value.
Since the first research was 20 years ago, a restudy of the present-day condition
of the scoria cone was conducted. Applying satellite imagery, remote sensing and
direct site visit, we find that about a third of the cone surface area has been modified
and at least a quarter of its volume has vanished. Further excavation for cone
material however opened the entire western side of the cone, exposing a nearly
5-m-thick succession of accidental lithic pyroclast-dominated lapilli tuff and tuff
breccia, confirming that this location had a significant phreatomagmatic phase in
its opening eruptions. This location shows graphically the need for geoconservation
to preserve such sites that are potentially the only, or best locations to show the
potential eruptive styles and scenarios of future eruptions if they occur in similar
environments.Published29-52OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Quantification of the Volcanic Carbon Dioxide in the Air of Vulcano Porto by Stable Isotope Surveys
No full textInjecting volcanic gas into the air leads to an increase in carbon dioxide (CO2) levels compared with background concentrations and may establish gas hazard conditions. This study reports the results of five stable isotope (i.e., δ13C-CO2 and δ18O-CO2) surveys of airborne CO2 on Vulcano from August 2020 to November 2021. To measure CO2 in the air, a mobile laboratory was equipped with a laser-based spectrophotometer that can selectively detect different CO2 isotopologues. Volcanic CO2 has a different isotopic signature than atmospheric CO2 and both δ13C-CO2 and δ18O-CO2 can help trace the injections of volcanic gases into the air. An isotopic mass balance model was developed for partitions CO2 between atmospheric background and volcanic CO2. The results of these studies show that volcanic CO2 emissions and atmospheric circulation deeply affected the concentration of CO2 in the air at Vulcano Porto. Studies of δ13C-CO2 and δ18O-CO2 provide an estimate of volcanic CO2 in the air. These results help identify spatially some points of interest for mitigating volcanic gas emission-related hazards on Vulcano.Istituto Nazionale di Geofisica e VulcanologiaPublishede2022JD0377066A. Geochimica per l'ambiente e geologia medicaJCR Journa
The whole story: Rumors and science communication in the aftermath of 2012 Emilia seismic sequence
No full textControversies that stir the public debate on geological matters usually revolve around a few specific aspects, including the actual trigger of geological phenomena (i.e., natural vs. anthropogenic), their predictability, and the trustworthiness of the experts who provide information and advice on the phenomena. A typical example of such difficulties is the case of the 2012 Emilia, Italy, seismic sequence which struck an area of relatively moderate seismic hazard. In that period, geophysical prospecting was planned to assess the potential of a reservoir for gas storage, near the town of Rivara. The low frequency of important seismic events in the area, associated with the ongoing industrial planning prompted widespread rumors of an anthropogenic origin of the 2012 earthquakes. Controversy also arose about the actual size of the seismic events: earthquakes magnitude can be computed with different methods, and its value depends on the type, number, and geographical distribution of the available seismic stations. As a result, different institutions commonly release different estimates of the earthquake magnitude, casting doubts on the reliability of each estimate. Since 2012, public concern has also been caused by the repeated occurrence of unusual phenomena in the area, such as ground heating or bubbling well waters. Popular belief tends to establish a causal link between particular phenomena and seismic activity, reinforcing the false conviction that seismicity could be predicted. In this work we present and discuss some of the activities that INGV pursued through the years to contrast rumors and disseminate correct scientific information. In the aftermath of the 2012 seismic sequence, INGV worked in collaboration with the National Department of Civil Protection, the local administrations, the University Network of seismic engineering, the Regional Healthcare System and local volunteer organizations. The organization of public meetings, the collection and analysis of widespread rumors and the creation of ad hoc outreach materials all contributed to reinforce the mutual trust between our research institute and the local population.
KEYWORDSPresidenza del Consiglio dei ministri, Dipartimento della Protezione Civile within the DPC-INGV 2012-2021 AgreementPublished10026485SR TERREMOTI - Convenzioni derivanti dall'Accordo Quadro decennale INGV-DPC3TM. ComunicazioneJCR Journa
Source-Parameter Estimation after Attenuation Correction through the Use of Q Tomography
No full textThe measurement of earthquake source parameters is affected by large uncertainties, and
different approaches lead to large variability in results. One crucial aspect is the trade-off
between attenuation (Q) and corner frequency (fc ) in spectral fitting: The source corner
frequency, inversely proportional to the fault size, can be severely masked by attenuation
and site effects. In this article, we describe a method to solve the trade-off based on the fit
of displacement spectra to find the source characteristics (corner frequency, f c , and the
signal moment, Ω0) and the single-station attenuation operator (t ), in addition to the site
response. We follow a parametric approach based on the use of 3D Q seismic tomography
and a bootstrap-based method for selecting the best spectra fit. The correction of attenu-
ation with synthetic values derived by 3D attenuation tomography efficiently deals with
the trade-off between source and path terms, leading to small uncertainties in the deter-
mination of source unknowns (f c and signal moment, Ω0 ), thus yielding constrained esti-
mates of source parameters for low- to medium-magnitude earthquakes. We show an
application to the Emilia 2012 seismic sequence, for which we computed the source param-
eters for 1240 aftershocks (from an initial dataset of 1748) with local magnitude ranging
from 2.0 to 4.7 using the spectral fit from P and S waves. About 80% of stress-drop esti-
mations are characterized by relatively low uncertainties (within 20% of the estimated
values), with maximum values of about 40% for the remaining 20%. The attenuation cor-
rection is effective to determine source parameters for small-magnitude earthquakes;
hence, we obtain reliable estimates of source parameters for the entire aftershock
sequence. This approach gives the opportunity to infer the mechanical state of a complete
fault system by taking advantage of the larger number of low-magnitude events (with
respect to the largest ones) that always follow a major earthquake.Published1739–1758OST3 Vicino alla fagliaJCR Journa