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Assessing volumes of tephra fallout deposits: a simplified method for data scarcity cases
No full textA new method for assessing volumes of tephra deposits based on only two thickness data is presented. It is based on the assumptions of elliptical shape for isopachs, a statistical characterization of their eccentricity, and an empirical relationship between their deposit thinning length scale and volumes. The method can be applied if the pair of thickness data are sufficiently distant from the volcano source, with a minimum distance ratio larger than 2. The method was tested against about 40 published volumes, from both equatorial belt and mid-latitude volcanoes. The results are statistically consistent with the published results, demonstrating the usefulness of the method. When applied in forward, the model allowed us to calculate the volume for some important tephra layers in the Mediterranean tephrostratigraphy, providing, for the first time, an assessment of the size of these eruptions or layers.Published62OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Are Foreshocks Fore‐Shocks?
No full textForeshocks are spatially clustered seismic events preceding large earthquakes. Since the dawn of seismology, their occurrence has been identified as a possible mechanism leading to further crustal destabilization, hence, to major failures. However, several cases occurred without any previous anomalous seismic activity, so that the hypothesis of foreshocks as reliable seismic precursors fails to pass statistical tests. Here, we perform an all‐round statistical comparative analysis of seismicity in Southern California to assess whether any differences can be identified between swarms and foreshocks. Our results suggest that extremely variable seismic patterns can forerun mainshocks, even though they tend to be preceded by clusters with more numerous events spread over larger areas than swarms and with a wider range of magnitudes. We provide a physical explanation of such dissimilarity and conclude, despite it, that foreshocks can hardly be reliable short‐ term precursors of large earthquakes in California.Publishede2023JB027337OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impattoJCR Journa
Marcello Carapezza (1925-1987), a pioneer of geochemical surveillance of active volcanoes
No full textMarcello Carapezza (1925-1987) was an Italian geochemist and professor of Applied Geochemistry at the University of Palermo during the 1970s and 1980s. He is widely recognised as a man of culture and a pioneer in the field of geochemical monitoring applied to volcanic surveillance. Carapezza played a crucial role in developing the first apparatus for detecting the geochemical parameters of an active volcano, specifically on the island of Vulcano in the Aeolian Islands, where he established a system for the continuous transmission of data to a surveillance center. Carapezza's initiatives were instrumental in fostering the growth of an Italian applied geochemistry school. His contributions extended beyond research and teaching, as he actively engaged in popularizing scientific knowledge through the media. This article aims to present a portrait of Marcello Carapezza by highlighting some notable moments from his career as both a scientist and a promoter of scientific culture.Published82-88JCR Journa
Nature-Based Options for Improving Urban Environmental Quality: Using Black Poplar Trees for Monitoring Heavy Metals Pollution in Urbanized Contexts
No full textSeveral researchers recognize the importance of plants as effective tools for environmental biomonitoring. The black poplar (Populus nigra L.) often emerges as a useful bioindicator of air quality in urban environments, where this tree species is widely employed for urban areas. Here, we used ICP-MS analysis to assess the presence and concentration of trace elements, with a special focus on heavy metals (HMs), in black poplar leaves and soil samples from three urbanized sites showing varying degrees of environmental quality. Specifically, the foliar concentrations of Zn (173.3 ppm), Cd (0.7 ppm), Co (1.1 ppm) and As (0.2 ppm) exceeded reference values for unpolluted sites, indicating potential environmental hazards. Additionally, we correlated the foliar concentrations of HMs with those quantified in soil and with air quality data provided by the regional air quality-monitoring network. Subsequently, we estimated the values of foliar fluctuating asymmetry, and evaluated their relationships with HM concentrations in both leaves and soil. Our results suggest that element concentrations in black poplar leaves are related to soil contamination and atmospheric quality, and the extent depends on the proximity to relevant pollution sources. Furthermore, the study species showed a pronounced accumulation capacity for some HMs (i.e., Zn, Cd) commonly found in particulate matter. The extent of foliar fluctuating asymmetry is related to atmospheric quality and HM soil concentration, possibly because of the growth anomalies induced by this kind of environmental contamination. Overall, our data indicate the study species can supply an effective biomonitoring service in urbanized contexts, offering valuable insights into the occurrence and biological implications of heavy metal contamination.Published85JCR Journa
Matlab Interface for Seismo‐Acoustic aRray Analysis (MISARA)
No full textVolcanic activity generates diverse seismic and acoustic signals that offer valuable insights into the underlying magmatic processes. Contemporary volcano monitoring relies on networks and arrays of seismic and acoustic sensors. The analysis of signals acquired by these instruments necessitates streamlined workflows and specialized software. The high sampling rates, typically exceeding 50 Hz, employed in recording seismic and acoustic waveforms by multi-station networks and dense arrays result in the swift accumulation of substantial data volumes, posing a formidable challenge in establishing efficient data analysis workflows for volcano surveillance.
In this context, we introduce MISARA (Matlab Interface for Seismo-Acoustic aRray Analysis), an open-source MATLAB graphical user interface. MISARA is meticulously crafted to furnish a user-friendly workflow for analyzing seismo-acoustic data in volcanic settings. It incorporates efficient algorithmic implementations of established techniques for seismic and acoustic data analysis, with a focus on supporting the visualization, characterization, detection, and location of volcano seismo-acoustic signals. The intuitive and modular structure of MISARA facilitates swift, semi-automated data inspection and result interpretation, thereby minimizing user effort.
Validation of MISARA involved testing it with seismo-acoustic data recorded at Etna Volcano (Italy) during 2010, 2011, and 2019. The tool is intended for educational and research purposes and is well-suited to aid routine data analysis at volcano observatories. Its open-source nature encourages collaborative development and adaptation, fostering advancements in volcano monitoring and contributing to the broader scientific community.PublishedVienn
Improving the Accuracy of Digital Terrain Models Using Drone-Based LiDAR for the Morpho-Structural Analysis of Active Calderas: The Case of Ischia Island, Italy
No full textOver the past two decades, the airborne Light Detection and Ranging (LiDAR) system has
become a useful tool for acquiring high-resolution topographic data, especially in active tectonics
studies. Analyzing Digital Terrain Models (DTMs) from LiDAR exposes morpho-structural elements,
aiding in the understanding of fault zones, among other applications. Despite its effectiveness,
challenges persist in regions with rapid deformation, dense vegetation, and human impact.
We propose an adapted workflow transitioning from the conventional airborne LiDAR system to
the usage of drone-based LiDAR technology for higher-resolution data acquisition. Additionally,
drones offer a more cost-effective solution, both in an initial investment and ongoing operational
expenses. Our goal is to demonstrate how drone-based LiDAR enhances the identification of active
deformation features, particularly for earthquake-induced surface faulting. To evaluate the potential
of our technique, we conducted a drone-based LiDAR survey in the Casamicciola Terme area,
north of Ischia Island, Italy, known for the occurrence of destructive shallow earthquakes, including
the 2017 Md = 4 event. We assessed the quality of our acquired DTM by comparing it with existing
elevation datasets for the same area. We discuss the advantages and limitations of each DTM product
in relation to our results, particularly when applied to fault mapping. By analyzing derivative
DTM products, we identified the fault scarps within the Casamicciola Holocene Graben (CHG) and
mapped its structural geometry in detail. The analysis of both linear and areal geomorphic features
allowed us to identify the primary factors influencing the current morphological arrangement of
the CHG area. Our detailed map depicts a nested graben formed by two main structures (the Maio
and Sentinella faults) and minor internal faults (the Purgatorio and Nizzola faults). High-resolution
DEMs acquired by drone-based LiDAR facilitated detailed studies of the geomorphology and fault
activity. A similar approach can be applied in regions where the evidence of high slip-rate faults is
difficult to identify due to vegetation cover and inaccessibility.Published1899OST3 Vicino alla fagliaJCR Journa
New constraints on the shear wave velocity structure of the Ivrea geophysical body from seismic ambient noise tomography (Ivrea-Verbano Zone, Alps)
No full textWe performed seismic ambient noise tomography to investigate the shallow crustal structure around the Ivrea geophysical body (IGB) in the Ivrea-Verbano Zone (IVZ). We achieved higher resolution with respect to previous tomographic works covering the Western Alps, by processing seismic data collected by both permanent and temporary seismic networks (61 broad-band seismic stations in total). This included IvreaArray, a temporary, passive seismic experiment designed to investigate the IVZ crustal structure. Starting from continuous seismic ambient noise recordings, we measured and inverted the dispersion of the group velocity of surface Rayleigh waves (fundamental mode) in the period range 4–25 s. We obtained a new, 3-D vS model of the IVZ crust via the stochastic neighbourhood algorithm (NA), with the highest resolution between 3 to 40 km depth. The fast and shallow shear wave velocity anomaly associated with the IGB presents velocities of 3.6 km s−1 directly at the surface, in remarkable agreement with the location of the exposed lower-to-middle crustal and mantle outcrops. This suggests a continuity between the surface geological observations and the subsurface geophysical anomalies. The fast IGB structure reaches vS of 4 km s−1 at 20–25 km depth, at the boundary between the European and Adriatic tectonic plates, and in correspondence with the earlier identified Moho jump in the same area. The interpretation of a very shallow reaching IGB is further supported by the comparison of our new results with recent geophysical investigations, based on receiver functions and gravity anomaly data. By combining the new geophysical constraints and the geological observations at the surface, we provide a new structural interpretation of the IGB, which features lower crustal and mantle rocks at upper crustal depths. The comparison of the obtained vS values with the physical properties from laboratory analysis of local rock samples suggests that the bulk of the IGB consists of a combination of mantle peridotite, ultramafic and lower crustal rocks, bound in a heterogeneous structure. These new findings, based on vS tomography, corroborate the recent interpretation for which the Balmuccia peridotite outcrops are continuously linked to the IGB structure beneath. The new outcomes contribute to a multidisciplinary framework for the interpretation of the forthcoming results of the scientific drilling project DIVE. DIVE aims at probing the lower continental crust and its transition to the mantle, with two ongoing and one future boreholes (down to 4 km depth) in the IVZ area, providing new, complementary information on rock structure and composition across scales. In this framework, we constrain the upper crustal IGB geometries and lithology based on new evidence for vS, connecting prior crustal knowledge to recent active seismic investigations.Published1089–1105OST1 Alla ricerca dei Motori GeodinamiciJCR Journa
Translation, collision and vertical‐axis rotation in the Organyà and Montsec minibasins (South‐Central Pyrenees, Spain)
No full textThis paper presents a sequentially restored cross-section of the Organyà and Montsec minibasins based on geological mapping, new field observations and available borehole data. The main objective was to describe the geometry and evolution of both basins in terms of salt tectonics and minibasin mobility. To this end, a comprehensive palaeomagnetic database has been used to constrain vertical-axis rotations potentially related to minibasin translation and pivoting. The Organyà minibasin constitutes an asymmetric depocentre formed during the Upper Jurassic-Lower Cretaceous by translation above a southerly inclined salt layer. Salt evacuation and minibasin touchdown induced salt accumulation on the northern side of the basin that culminated in the development of the major Santa Fe unconformity during the late Albian—early Cenomanian. Indicative of salt quiescence is the following isopachous Cenomanian to lower Santonian sequence Salt tectonics resumed during the late Santonian—Palaeocene, with the Montsec minibasin downbuilding coinciding with the onset of Pyrenean convergence. Changes of the base-salt topography reflects regional-scale geodynamic processes. The acceleration of crustal thinning in the North Pyrenean zone during the late Albian-early Cenomanian favoured uplift in the Axial Zone, increasing slope and triggering salt mobilization in the Southern Pyrenees. Likewise, the onset of contraction renewed the downslope gliding of the Organyà and Montsec minbasins, and supports the idea that the early stages of basin inversion were governed by gravity tectonics. The kinematic reconstruction suggests that the more that 30° counterclockwise vertical axis rotation records pivoting during the suprasalt translation of the Organyà minibasin rather than solely the Iberian microplate rotation.Publishede12846OSA1: Variazioni del campo magnetico terrestre, imaging crostale e sicurezza del territorioJCR Journa
Vertical Displacements and Sea‐Level Changes in Eastern North America Driven by Glacial Isostatic Adjustment: An Ensemble Modeling Approach
No full textGlacial isostatic adjustment (GIA) describes the response of the solid Earth, oceans, and gravitational field to the spatio‐temporal evolution of ice sheets during a glacial cycle. Present‐day vertical displacements and sea‐level changes vary throughout eastern North America in response to the melting of the Laurentide Ice Sheet following the Last Glacial Maximum. We use the open‐source software SELEN4.0 (a SealEveL EquatioN solver) to investigate the influence of GIA on vertical land motions and sea‐level changes in eastern North America. Further, we evaluate the uncertainties associated with the lithospheric thickness and viscosity structure using an ensemble modeling approach (129,956 total simulations). We identify the best‐fitting rheological profiles by comparing modeled vertical displacements to vertical velocity rates derived from Global Positioning System (GPS). We find a general pattern of subsidence (causing accelerated relative sea‐level rise) in the eastern United States region and uplift (causing relative sea‐level fall) in the eastern Canada region consistent with previous studies for two tested ice sheet models (ICE‐6G(VM5a) and ICE‐7G(VM7)). Overall, we find lower rates of modeled vertical displacement using ICE‐6G(VM5a) compared with ICE‐7G(VM7), which produces lower residuals when compared with the GPS‐derived vertical velocity rates. Our ensemble analysis identifies adjustments to the nominal VM5a and VM7 viscosity models that improve fits to the GPS‐imaged vertical velocity rates throughout eastern North America and on the North American Atlantic Coast. The differences in our best‐fitting models for inland versus coastal regions highlight the importance of exploring lateral viscosity variations for GIA modeling throughout North America and elsewhere.Publishede2023JB028250JCR Journa
A theoretical comparison among macroseismic scales used in Italy
No full textIn a recent work, we evidenced some empirical discrepancies between the macroseismic
intensity estimates in Italy in the last decade with respect to those made previously. A possible
reason might be the progressive adoption by Italian researchers of the European Macroseismic
Scale (EMS) in place of the Mercalli Cancani Sieberg (MCS) scale mostly used
up to 2009. In theory, in modern settlements where reinforced concrete (RC) buildings are
increasingly replacing those in masonry, EMS should overestimate MCS because the former
accounts for the lower vulnerability of RC whereas the latter does not because RC
buildings were not considered at all by the MCS scale since they were almost absent at the
time (1912–1932) when it was compiled by Sieberg. However, such theoretical inference is
contradicted by the empirical evidence that, on average, MCS intensities really estimated
in Italy over the past decade slightly overestimate EMS and not vice versa as it should be.
A possible explanation is that the EMS scale had not been well calibrated to reproduce the
MCS, as its authors intended to do. Another possible reason for the discrepancies between
the last decade and the previous ones might be that the MCS scale applied today is not the
same as that defined by Sieberg at the beginning of the twentieth century. In order to better
understand the possible causes of such discrepancies, we present here a formal comparison
between the definitions of the different degrees of such macroseismic scales. After such
analysis, we might argue that another possible reason for the observed discrepancy may
come from the inaccurate assessment of building vulnerability when assessing the EMS
intensity.Published4245–4263OST2 Deformazione e Hazard sismico e da maremotoJCR Journa