Search

Historic volcanic activity in Tenerife was concentrated within two of the island's three dorsals and on the Teide-Pico Viejo complex located inside Las Cañadas caldera. Eruptions on the island are primarily characterised by basaltic and trachybasaltic fissural eruptions. However, the Teide-Pico Viejo complex also hosted explosive and effusive phonolitic eruptions. Our study focused on the analysis of the 2004-2005 unrest in Tenerife, which was characterised by an onset of a ground deformation pattern, heightened on-land seismic activity, changes in the chemical composition of fumaroles of the Teide composite volcano, an increase in diffusive emissions of carbon dioxide along the NW rift, and, significant gravity changes. We used the Envisat-ASAR satellite images from 2003 to 2010 to generate the Line-Of-Sight SBAS- DInSAR deformation time series to investigate the source responsible for ground deformation. We applied the Independent Component Analysis (ICA) to separate distinct ground deformation patterns. Specifically, we selected four components for the Independent Component Analysis decomposition: the first one mainly affects the stratovolcano's summit region of Teide and shows a circular symmetry; the second and third components are possibly related to the topography and atmospheric artifacts, while the fourth contains only a noisy signal. We employed a non-linear optimisation approach in a Finite Element modelling environment to determine the source geometry responsible for the first identified ICA pattern of ground deformation within Las Cañadas. Our results revealed the existence of an ellipsoidal ground deformation source oriented along the E-W axis, located beneath the Teide and Montaña Blanca volcanoes at 1,600 m a.s.l. This source became active during the seismic crisis of 2004-2005, which was associated with the degassing of a magma batch that intruded into the northwest rift of Tenerife island. We propose that the ground deformation observed at Teide volcano during the 2004-2005 crisis was related to hydrothermal activity within the volcano. [ABSTRACT FROM AUTHOR]

The deformation style of active volcanoes can provide insight into the structural evolution of their edifices, volcanic activity and associated hazards. The Somma‐Vesuvius volcano is considered one of the most dangerous on the planet due to its proximity to the megacity of Naples (Southern Italy). Thus, understanding its deformation style and corresponding long‐term structural evolution are critical aspects for risk reduction. Although a large amount of data has already been collected about Somma‐Vesuvius, the deformation style affecting its volcanic edifice is still debated. Therefore, we devised an integrated approach to clarify the current state of deformation of this volcano. In particular, we combined analog experiments and finite element (FE) modeling to constrain the current deformation style affecting Somma‐Vesuvius and determine the physical parameters controlling its structural evolution. The analog models were built at a scale of 1:100,000 using sand mixtures (brittle analog) and polydimethylsiloxane (ductile analog). The FE models were implemented by considering a three‐dimensional time‐dependent fluid‐dynamic approach performed at both the analog model scale (1:100,000) and actual volcano scale (1:1). We obtained an FE model and a corresponding analog one that faithfully reproduced the observed deformation velocity patterns revealed by differential interferometric synthetic aperture radar (DInSAR) and GPS measurements at Somma‐Vesuvius. Overall, our results support the hypothesis that a combined gravitational spreading‐sagging process governs the deformation style of Somma‐Vesuvius. Plain Language Summary: Volcanic edifices of sufficient mass are capable of deforming substrata under their own weight; this deformation in turn can deform the volcanic edifices themselves. Identifying the deformation style characterizing a volcanic edifice is useful when considering the evolution of its volcanic activity. Vesuvius is considered one of the most dangerous volcanoes on the planet due to its proximity to the megacity of Naples (Southern Italy). Thus, understanding its deformation style and corresponding structural evolution are critical aspects for risk reduction. In order to analyze the deformation process of Vesuvius we used two different modeling techniques: analog modeling and Finite Element numerical modeling. The analog modeling approach allows us to reproduce real processes by using scaled models and media considered analog to natural materials under a physical point of view. The combination of analog and numerical modeling allowed us to constrain the current deformation style affecting Somma‐Vesuvius and to determine the physical parameters controlling its structural evolution. Finally, we compared our results with the observed deformation velocity patterns revealed by Differential Interferometric Synthetic Aperture Radar and GPS measurements at Vesuvius. Overall, the results support the hypothesis that a combined gravitational spreading‐sagging process governs the deformation style of Somma‐Vesuvius. Key Points: Analog and numerical modeling highlighted an active spreading‐sagging process at the Somma‐Vesuvius volcanoA comparison of models with differential interferometric synthetic aperture radar (DInSAR) deformation data validated the modeling proceduresThe spreading process affecting the Vesuvius volcano allowed inferring about the near‐future eruption style [ABSTRACT FROM AUTHOR]

In this paper, we propose an advanced methodology to perform three-dimensional (3D) Finite Element (FE) modeling to investigate the kinematical evolution of a slow landslide phenomenon. Our approach benefits from the effective integration of the available geological, geotechnical and satellite datasets to perform an accurate simulation of the landslide process. More specifically, we fully exploit the capability of the advanced Differential Synthetic Aperture Radar Interferometry (DInSAR) technique referred to as the Small BAseline Subset (SBAS) approach to provide spatially dense surface displacement information. Subsequently, we analyze the physical behavior characterizing the observed landslide phenomenon by means of an inverse analysis based on an optimization procedure. We focus on the Ivancich landslide phenomenon, which affects a residential area outside the historical center of the town of Assisi (Central Italy). Thanks to the large amount of available information, we have selected this area as a representative case study highlighting the capability of advanced 3D FE modeling to perform effective risk analyses of slow landslide processes and accurate urban development planning. In particular, the FE modeling is constrained by using the data from 7 litho-stratigraphic cross-sections and 62 stratigraphic boreholes; and the optimization procedure is carried out using the SBAS-DInSAR retrieved results by processing 39 SAR images collected by the Cosmo-SkyMed (CSK) constellation in the 2009-2012 time span. The achieved results allow us to explore the spatial and temporal evolution of the slow-moving phenomenon and via comparison with the geomorphological data, to derive a synoptic view of the kinematical activity of the urban area affected by the Ivancich landslide. [ABSTRACT FROM AUTHOR]

The 2012 Emilia sequence (Northern Apennines, Italy) represents one of the largest Italian seismic sequences occurring in a continental active compressional tectonic setting and strikes the Ferrara Arc, at the Padan buried front of the northern Apennines Outer Thrust System. The sequence begins on 20 May 2012 with a Mw 6.1 earthquake; before this event, the local seismometric network records five foreshocks that reached a maximum magnitude of 4.1. On 29 May, a Mw 6.0 event occurs about 15 km southwest of the first shock on an adjacent fault segment. After this second mainshock, seismicity further propagates westward, in a portion of the fault system close to the lateral termination of the Ferrara arc, where three more ML ≥ 5.0 aftershocks occur between May 29 and June. The existing literature substantially agrees in associating the 20 May Mw 6.1 mainshock to the middle segment of the Ferrara Thrust System (FTS), whereas the debate is mostly focused on attributing the 29 May Mw 6.0 earthquake to the inner segment of the Ferrara Thrust System or, rather, to the outer segment of the Mirandola Thrust System (MTS). Note that the FTS and MTS represent two near parallel, well distinct, fold-and-thrust systems of the north-verging Ferrara Arc. In this work, we propose a new 3D reconstruction of the main faults involved during the 2012 Emilia multi-events seismic sequence. We show that the 20 May and the 29 May events nucleate along the Middle and the Inner S-dipping splays of the Ferrara Thrust system, respectively. These two thrust segments are along-strike connected by an up to now unnoticed left-lateral transfer fault. This linkage may have controlled the location and the timing of the two subsequent major ruptures throughout the sequence. In order to verify our findings and to constrain the best possible earthquake/fault association, we start our analysis by developing a 3D fault model of the investigated area. In particular, in order to create this 3D FE model and to consider the heterogeneities present in the seismogenic volume, we take into account the collected geological information of the selected area, the relocated seismicity and the Vp/Vs tomographic models. Subsequently, we further extend our analysis by applying a 3D numerical modelling approach based on the finite elements method (FEM), implemented in a structural-mechanic framework; this allows us to simulate the ground deformation patterns retrieved through the DInSAR measurements obtained from the radar data acquired by the RADARSAT-2 sensor. Finally, we retrieve the volumetric distribution of the coseismic strain and stress variation, responsible for the observed ground deformation pattern. [ABSTRACT FROM AUTHOR]

This work intends to present the main activities and the most significant results that the Institute for Electromagnetic Sensing of the Environment (IREA) of the National Research Council (CNR) has retrieved within the framework of its collaboration with the Ministry of Economic Development (MiSE) – Directorate-General for Safety of Mining and Energy Activities National Mining Office for Hydrocarbons and Georesources (DGS-UNMIG). In particular, the IREA-CNR/MiSE-DGS-UNMIG agreement aims at investigating surface deformation affecting the areas of the Italian territory of particular interest for the DGS-UNMIG through space-borne Differential SAR (Synthetic Aperture Radar) Interferometry (DInSAR) analysis and multi-parameters and multi-physics modelling. To this aim, we exploit SAR data acquired from the first- and second-generation sensors, processed via the advanced DInSAR technique known as SBAS (Small BAseline Subset) approach, to detect and follow the temporal evolution of the surface displacements via the generation of mean deformation velocity maps and corresponding time-series. More specifically, we focus on the SAR data collected along ascending and descending orbits by the Sentinel-1 constellation of the Copernicus Program of the European Union to map the whole Italian Peninsula during the 2015-2018 time interval, thus providing information on the spatial distribution of the retrieved ground displacements and their temporal evolution. Moreover, we model the geological and geophysical processes that characterize the geothermal reservoir of Casaglia site (Northern Italy), which is the selected study area. In particular, we proceed to the definition and implementation of a geological / structural database and the building of a 3D stratigraphic-structural model of the Casaglia area. This model represents the basis from which a model of circulation of fluids will be developed with the Finite Element method, which will mainly concern the study of spatio-temporal variations of stress and strain in the region outside the reservoir, and the evaluation of any correlations between seismicity and the circulation of fluids. [ABSTRACT FROM AUTHOR]