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Geomorphologic and structural map of the Ischia Island. Structural and volcanic features from Vezzoli (1988), Chiodini et al. (2004), and de Vita et al. (2006)
Source publication
In this paper, a high-resolution digital elevation model (DEM) of the Ischia Island has been created, and a digital terrain
analysis has been carried out to identify of morphostructural elements of this landscape. Ischia is an active volcano located
in the Western sector of the Gulf of Naples that is characterized by historical and recent volcano-t...
Contexts in source publication
Context 1
... continued, with quiescence periods, until 1302 A.D., when the Arso lava flow eruption took place. In the last 30 ky, an uplift of about 900 m has occurred ( Orsi et al. 1991). The uplift has been controlled by a set of sub-parallel NW-SE to N-S striking faults in the western sector of Mt. Epomeo and by NE-SW to E-W faults in its northern sector (Fig. 2). In the eastern sector of the island, N-S and NE-SW striking fractures and faults control the location of the vents (Fig. 8a, Foglio CARG ...
Context 2
... Ischia Island has been characterized by intense hydrothermal activity, which includes fumaroles, hot springs, and diffuse degassing areas ( Chiodini et al. 2004). This activity is concentrated along faults bounding the northern and western flanks of Mt. Epomeo (Fig. 2). Leveling surveys and space-borne Synthetic Aperture Radar images collected between 1993 and 2003 indicate that the flanks of Mt. Epomeo have shown subsidence with a rate of 1.27 cm/year ( Manzo et al. 2006;Sepe et al. ...
Context 3
... flank, high values of topographic residual surface correspond to deep incisions and numerous debris flows reported by Tibaldi and Vezzoli (2004). The morphostructural lineaments are lacking in the eastern sector of the island where most morphological features are represented by young and small volcanic cones, craters, domes, and lava flows (Fig. ...
Citations
... Vezzoli, 1998, andSbrana et al., 2018) [30,31]. The fault structures outside the study area (black dotted square) are based on Vezzoli (1988); Nappi et al. (2010), and Sbrana et al. (2018) [31][32][33]. The 2017 epicentral location (blue star) is taken from De Novellis et al. (2018) [34], and the historical earthquakes from Selva et al. (2021) [35]. ...
... Vezzoli, 1998, andSbrana et al., 2018) [30,31]. The fault structures outside the study area (black dotted square) are based on Vezzoli (1988); Nappi et al. (2010), and Sbrana et al. (2018) [31][32][33]. The 2017 epicentral location (blue star) is taken from De Novellis et al. (2018) [34], and the historical earthquakes from Selva et al. (2021) [35]. ...
... The E-ENE normal fault system that borders the N flank of Mt. Epomeo has accommodated a maximum vertical displacement of ca. 1 km [30][31][32][33]45,48,52,53]. In the foothill area of Casamicciola Terme, a structure, part of the E-ENE fault system, separates Mt. ...
Over 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.
... Here, the term domain is intended to stress the importance of the azimuthal family rather than the individual lineament, which is commonly poorly visible by normal visual observations. Many scientists have erroneously tried to describe each lineament individually in terms of classical geological elements, such as fractures, faults, dykes, or crustal discontinuities (e.g., [15][16][17][18][19][20][21][22][23][24]). However, lineament domains are instead superficial manifestations of the crustal stress field trajectory-their mean azimuth is parallel to the maximum horizontal stress of the upper (rigid) crust of the region in which the domain occur [5,7,[9][10][11]14,25]. ...
... Lineament domain investigations in various geodynamic environments have previously been performed to: (i) highlight the tectonic setting and regional stress field of a region [3,7,9,10,12,[26][27][28]; (ii) better understand secondary permeability by identifying the directions of the most permeable faults and fractures in water/oil reservoirs [13,22,29,30]; (iii) to define the fracture pattern associated with main faults [9,31]; and (iv) to assess the volcano-tectonic setting and the fracture distribution in geothermal areas [23,[31][32][33][34][35]. All of these studies have revealed a relationship between lineament domains and recent/active tectonics in the studied region and confirm that they are indicators of active stress fields. ...
Regional-scale swarms of subparallel linear topographic features, known as lineament domains, are a common feature of planetary surfaces. Lineament domains are superficial manifestations of the crustal stress field trajectory. Notably, one of the effects of active tectonics is seismicity. Italy is one of the most seismically active regions in the Mediterranean, with many destructive earthquakes that have occurred in past centuries. Here, we assess the seismic meaning of the main lineament domain in the tectonically active region of Central Italy. We describe the use of an automated analysis of satellite imagery coupled with spatial grid analysis to identify three lineament domains of the Central Apennines. Spatial and azimuthal comparisons of the main lineament domain (i.e., the Apennine Domain), with the known locations of earthquakes (moment magnitude of Mw > 5.5) that occurred during the past century, revealed the most seismically active tectonic areas and their spatial distributions. Further, we present a conceptual seismo-geodynamic model for the Central Apennines, which is characterized by regional arching and explains the presence of an extensional tectonic regime in the upper crustal layer of the active Apennines fold-and-thrust belt.
... Depending 2 > REPLACE THIS LINE WITH YOUR MANUSCRIPT ID NUMBER (DOUBLE-CLICK HERE TO EDIT) < on the revisit time of the acquisitions, such kind of information can be exploited for rapid mapping and hazard assessment purposes thus supporting the stakeholders in the rescue of missing and in the management of post-crisis scenarios. [12]. The brown polygon indicates the mapping of the damaged areas (Grading product) due to the flooding, retrieved by the Copernicus Emergency Management Service (https://emergency.copernicus.eu/). ...
... According to the scheduling of the CSG mission, there is an acquisition every 16 days whereas the orbital tube of the mission is not so narrow with values of perpendicular baseline up to 1000m. For geocoding the output products, the Digital Elevation Model (DEM) by Nappi et al., (2010) [12] was used. It has been obtained by digitizing contour maps and spot elevation in vector format (scale 1:2,000) provided by the Consorzio Intercomunale Servizi Ischia. ...
In this work several change detection techniques based on satellite SAR data acquired by Cosmo-SkyMed Second Generation missions have been evaluated aiming at detecting the landslide-mudflow phenomenon triggered by the strong flooding event that hit Ischia Island in November 2022. It severely impacted on Casamicciola Terme area causing damages and collapses of many buildings and unfortunately also casualties. Experimental results show how both Single- (SP) and Dual- (DP) Polarimetric techniques are able to detect the main landslide occurring along the northern flank of Mt. Epomeo and in some cases also connected phenomena such as mud accumulation. Additional analyses have been performed to quantitatively evaluate the performance of all of them showing as in this case DP techniques outperform the SP ones. The outcomes are then discussed taking into account both the features of each technique and the investigated scenario. Detecting and mapping this kind of phenomena is important for the evaluation of the affected area, especially for complex scenarios such as Ischia island, and can be very useful to support both the stakeholders for the first aid and the Civil Protection for the post-crisis management.
... They suggested that the 21 August earthquake was caused by reactivation of the E-W normal fault system that is associated with the Holocene uplift of the Mt Epomeo N flank (blue lines in Figure 1). Its geometric characteristics are similar to the causative faults of historical strong earthquakes in the same area during 18-19 centuries (1762, 1767, 1796, 1828, 1881, and 1883), with maximum observed MCS intensities ranging between VII and XI (Selva Geostructural sketch map on the shaded relief in UTM WGS-84 geographic coordinates by Nappi et al. (2010). The featured stratigraphic units are simplified from Sbrana et al. (2018). ...
... The featured stratigraphic units are simplified from Sbrana et al. (2018). Faults (in black) are from Funiciello (1999) andde Vita et al. (2010), and geomorphological lineaments (in black), from Nappi et al. (2010); active normal faults (red lines, marks on down-thrown side) are from Vezzoli (1998) and Tibaldi and Vezzoli (1998); the coseismic ruptures (yellow lines) and causative fault (blue line) of 2017 earthquake and rose diagram of the same are from Nappi et al. (2018b); surface trace of the 2017 earthquake causative fault (blue line) from this paper; and the 21 August 2017 mainshock (the yellow biggest star) is from https://terremoti.ov.ingv.it/gossip/ischia/2017/index.html. ...
In this paper, we investigated ground motion directional amplification and horizontal polarization using ambient noise measurements performed in the northern sector of Ischia Island which suffered damage (VIII EMS) during the 21 August 2017, Md 4.0 earthquake. Over 70 temporary seismic stations were installed by the INGV EMERSITO task force, whose aim is to monitor site effects after damaging earthquakes in Italy. To investigate ground motion directional amplification effects, we have applied three different techniques, testing their performance: the HVSR calculation by rotating the two horizontal components, the covariance matrix analysis, and time–frequency domain polarization analysis. These techniques resulted in coherent outcomes, highlighting the occurrence of directional amplification and polarization effects in two main sectors of the investigated area. Our results suggest an interesting pattern for ground motion polarization, that is mainly controlled by recent fault activity and hydrothermal fluid circulation characterizing the northern sector of the Ischia Island.
... Widespread damage was also observed in the Fango and Lacco Ameno locality (I = VII EMS), while sporadic and very slight damages (I = V EMS) were reported in the remaining municipalities [5][6][7][8]. [4]; black lines, active normal faults from [9][10][11][12][13][14]; grey lines, other faults of the Ischia Volcano [11][12][13]; cyano squares, historical seismicity from [14] (macroseismic scale MCS, Mercalli-Cancani-Sieberg; [15]); yellow star shows the mainshock, Md 4.0, with its focal mechanism for the 2017 seismic event from [2]; inset map, the study region in a larger location map of Italy. [4]; black lines, active normal faults from [9][10][11][12][13][14]; grey lines, other faults of the Ischia Volcano [11][12][13]; cyano squares, historical seismicity from [14] (macroseismic scale MCS, Mercalli-Cancani-Sieberg; [15]); yellow star shows the mainshock, Md 4.0, with its focal mechanism for the 2017 seismic event from [2]; inset map, the study region in a larger location map of Italy. ...
... Widespread damage was also observed in the Fango and Lacco Ameno locality (I = VII EMS), while sporadic and very slight damages (I = V EMS) were reported in the remaining municipalities [5][6][7][8]. [4]; black lines, active normal faults from [9][10][11][12][13][14]; grey lines, other faults of the Ischia Volcano [11][12][13]; cyano squares, historical seismicity from [14] (macroseismic scale MCS, Mercalli-Cancani-Sieberg; [15]); yellow star shows the mainshock, Md 4.0, with its focal mechanism for the 2017 seismic event from [2]; inset map, the study region in a larger location map of Italy. [4]; black lines, active normal faults from [9][10][11][12][13][14]; grey lines, other faults of the Ischia Volcano [11][12][13]; cyano squares, historical seismicity from [14] (macroseismic scale MCS, Mercalli-Cancani-Sieberg; [15]); yellow star shows the mainshock, Md 4.0, with its focal mechanism for the 2017 seismic event from [2]; inset map, the study region in a larger location map of Italy. ...
... [4]; black lines, active normal faults from [9][10][11][12][13][14]; grey lines, other faults of the Ischia Volcano [11][12][13]; cyano squares, historical seismicity from [14] (macroseismic scale MCS, Mercalli-Cancani-Sieberg; [15]); yellow star shows the mainshock, Md 4.0, with its focal mechanism for the 2017 seismic event from [2]; inset map, the study region in a larger location map of Italy. [4]; black lines, active normal faults from [9][10][11][12][13][14]; grey lines, other faults of the Ischia Volcano [11][12][13]; cyano squares, historical seismicity from [14] (macroseismic scale MCS, Mercalli-Cancani-Sieberg; [15]); yellow star shows the mainshock, Md 4.0, with its focal mechanism for the 2017 seismic event from [2]; inset map, the study region in a larger location map of Italy. Top, map of the coseismic ruptures, secondary environmental effects and collapse of drywall (data reported because located in the immediate vicinity of ground effects) in the epicentral area of the 21 August 2017, earthquake [4], overlapped on the geological map of [16]; black line is the synthetic active fault and blu line is the antithetic Holocene normal fault scarps of the Casamicciola Terme graben (ticks mark the downthrown side); bottom, geological cross-sections of the epicentral area, with structural details of the Holocene graben [9], trace location on the top. ...
On 21 August 2017 at 20:57 (local time) a very shallow (H = 1.2 km), moderate (Md = 4.0), earthquake hit the volcanic island of Ischia (Southern Italy), causing the death of two people. The study of the damage to the buildings with the European Macroseismic Scale 98 (EMS-98), carried out immediately after the earthquake, highlighted that hilly area of Casamicciola Terme, on the northern side of the Mt. Epomeo, was the most damaged part of the island with locally quite relevant damage (I = VIII EMS). This seismic event is the first damaging earthquake in Ischia during the instrumental era. In fact, this provides, for the first time, the opportunity to integrate historical seismicity, macroseismic observations, instrumental information, and detailed mapping of the geological coseismic effects. In this work we evaluate the effects induced by the 2017 Casamicciola earthquake on the environment using the Environmental Seismic Intensity 2007 (ESI-07) macroseismic scale. This macroseismic analysis, together with the superficial coseismic faulting characteristics and the available geophysical information, allows us to reconsider the source model for the 2017 earthquake and the previous damaging historical earthquakes in the Casamicciola Terme area. The application of the ESI scale to the Casamicciola Terme earthquake of 21 August 2017 and the assignment of seismic intensity offers better spatial resolution, as well as an increase of the time window for the assessment of the seismic hazard, allowing to reduce the implicit uncertainty in the intensity attenuation laws in this peculiar volcano-tectonic setting. Since intensity is linked to the direct measure of damage, and it is commonly used in hazard assessment, we argue that building damage at Casamicciola Terme is strongly influenced by earthquake surface faulting and near field effects, and therefore controlled by the geometry of the seismic source.
... It is located on the Tyrrhenian border of central Italy, at the intersection of regional fault systems, with NW-SE (Appennine) and NE-SW (anti-Apennine) trends [19][20][21][22][23]. Ischia island rises over 1000 m above the seabed [46] and covers an area of 46.4 km 2 , it is morphologically dominated by Mt Epomeo (787 m above sea level), located in a central sector of the island along the NE-SW alignment of Mt Vezzi and Mt Cotto in the SE sector. The coast is characterized by steep cliffs and some less steep slopes that plunge into the sea [19,[47][48][49][50]. The volcanic activity started around 150 ky and was characterized by several effusive and explosive eruptions alternating with periods of quiescence [23,[46][47][48]. ...
... The volcanic activity started around 150 ky and was characterized by several effusive and explosive eruptions alternating with periods of quiescence [23,[46][47][48]. The most impacting event on the island is the caldera forming eruption of the Green Tuff of Mt Epomeo, which occurred 55 ky and caused the collapse of the central sector of the island, followed by resurgence of the Mt Epomeo block starting from 30 ky [23,[48][49][50]. The last eruption occurred in 1302 A.D. with the effusive eruption of Arso, located in the eastern sector of the island [23,51,52]. ...
In the present paper, we analyse ground tilt and seismicity at Campi Flegrei caldera and Ischia Island, two volcanic areas located in the south of Italy. These areas have been well studied for many years from a petrological, volcanological and geophysical view point. Moreover, due to the high seismic and volcanic risk for the populations living there, they are continuously monitored by networks of geophysical and geochemical sensors. We summarize the most important results that we obtained so far, concerning the observations of relationships between seismic activity and ground tilt anomalies, focusing on the time interval 2015-2018. First, we present a detailed description of the tiltmeter and seismic networks in both the investigated areas, as well as their development and improvement over time that has enabled high quality data collection. From the joint analysis of the seismic and borehole tiltmeter signals, we often notice concurrence between tilt pattern variations and the occurrence of seismicity. Moreover, the major tilt anomalies appear to be linked with the rate and energy of volcano-tectonic earthquakes, as well as with exogenous phenomena like solid Earth tides and hydrological cycles. The analysis that we present has potential applicability to other volcanic systems. Our findings show how the joint use tilt and seismic data can contribute to better understanding of the dynamics of volcanoes.
... The last period of volcanic ac-▴ Figure 1. Location of the coseismic geological effects on the shaded relief map by Nappi et al. (2010). Faults (in black) are from Funiciello (1999) andde Vita et al. (2010), and geomorphological lineaments (in black) from Nappi et al. (2010); active faults (lines with thick marks on down-thrown side) are from Vezzoli (1988) and Tibaldi and Vezzoli (1998); historical seismicity from Alessio et al. (1996). ...
... Location of the coseismic geological effects on the shaded relief map by Nappi et al. (2010). Faults (in black) are from Funiciello (1999) andde Vita et al. (2010), and geomorphological lineaments (in black) from Nappi et al. (2010); active faults (lines with thick marks on down-thrown side) are from Vezzoli (1988) and Tibaldi and Vezzoli (1998); historical seismicity from Alessio et al. (1996). The 21 August 2017 mainshock (the biggest star) with its focal mechanism and the main aftershocks (the smallest stars) are from De Novellis et al. tivity started 10 ka B.P., with eruptions in the eastern sector of the island including the most recent eruption of Arso in 1302 (de Vita et al., 2006;de Vita et al. 2010). ...
... Resurgence has been attributed to repeated injections of magma at depths of 2-3 km (Rittmann, 1930;Fusi et al., 1990;Orsi et al., 1991;Cubellis and Luongo, 1998;Tibaldi and Vezzoli, 1998;Acocella and Funiciello, 1999;Molin et al., 2003;Carlino et al., 2006;Paoletti et al., 2009;Sbrana et al., 2009;Carlino, 2012). It has been asymmetric with a maximum displacement on the northern flank, owing to the control of an E-W normal fault system (Vezzoli, 1988;Orsi et al., 1991;Tibaldi and Vezzoli, 1998;Acocella and Funiciello, 1999;Tibaldi and Vezzoli, 2004;de Vita et al., 2010;Nappi et al., 2010). Based on the distribution of marine deposits, eustatic variations and basin subsidence, the maximum uplift has been estimated at 920-970 m along the northern flank of Mt. ...
On 21 August 2017, a shallow earthquake of Md 4.0 struck the Casamicciola Terme village in the north of Ischia volcanic island (Italy). It caused two fatalities and heavy damage in a restricted area of a few square kilometers. Casamicciola Terme has been recurrently destroyed in the last centuries by similar volcano‐tectonic earthquakes (1762, 1767, 1796, 1828, 1881, and 1883). After the catastrophic 1883 Casamicciola event (2343 casualties), this is the first heavy damaging earthquake at Ischia that provides, for the first time, the opportunity of integrating historical seismicity, macroseismic observations, instrumental information, and detailed mapping of coseismic geological effects. Soon after the 2017 mainshock we surveyed the epicentral area to collect data on the coseismic ground effects, recording more than 100 geological field observations. Mapped effects define a belt which closely follows the trace of the Casamicciola E–W‐trending normal fault system, bounding the northern slope of Mt. Epomeo, previously known as a Latest Pleistocene to Holocene normal fault with a slip rate of ∼3.0 cm/yr. We found significant evidence for coseismic surface faulting, testified by a main alignment of ruptures for a 2 km end‐to‐end length and normal dip‐slip displacement of 1–3 cm. The geometry and regularity of the structural pattern, together with constant kinematics of the coseismic ruptures with the north side down, strongly suggest a primary tectonic origin for the mapped ruptures and strongly supports an E–W normal‐faulting focal mechanism for the 2017 Casamicciola earthquake. Macroseismic information supports the notion that previous historical events also had a similar style of faulting.
Valutazione ANVUR 2015-2019Al prodotto è stato attribuito punteggio complessivo pari a 29.5 ed è stato quindi classificato in classe A ( Eccellente ed estremamente rilevante )
... Thus, for both species the relationship is obvious (Hagemaijer and Blair, 1997;Moskát et al., 1993;Timiałoć and Stawarczyk, 2003;Cramp and Perrins, 1994). However, it is worth noticing that the preferred habitats, especially mixed arable fields and conifer- ous forest with complicated shapes and long ecotones, are usually arranged in upland (Kondracki, 2002;Xu et al., 2004;Asner et al., 2014;Nappi et al., 2010). Therefore, models without topographic metrics might lead to a conclusion that high densities of the Icterine warbler and the Eurasian golden oriole would be recorded only in the upland and/or areas with a high level of roughness; if we took only the distribution of preferred habitats and their geometry into account. ...
... We found a relatively low correlation coefficient between altitude, aspect and roughness and a higher correlation between altitude and slope; therefore we excluded the latter variable from the analysis. Furthermore, the discovered relationship between climate components and patch structure metrics may stem from simple relationships between geomorphology and geometry, where topographic heterogeneity influences a more complicated shape of patches (Asner et al., 2014;Nappi et al., 2010). If Poland's territory was divided into smaller geographic subregions based on topographic zones, it could turn out that in some places the shape of patches has a high correlation with roughness, while in others it would not. ...
Species Distribution Modelling (SDM) is a group of statistical tools that describe species distribution in environmental gradients in order to create their predictive distribution. However, due to the complexity of factors that influence the occurrence or density of species these methods’ effectiveness is still debatable. That is why we decided to explore how topographic metrics, such as altitude, slope, roughness and aspect, would affect the density of farmland (Icterine warbler) and forest (Eurasian golden oriole) bird species. We generated two sets of SDMs for each of the two bird species: One set of models contained topographic metrics as a predictor variable, and the other did not. Out-of-back procedures in the Random Forest approach and evaluation models based on independent dataset scores showed that omitting topographic metrics as predictors resulted in a substantial reduction of model performance for both lowland and upland bird species. Further analysis of predictive maps revealed that neglecting topographic metrics resulted in large over-predictions of species’ densities in regions where these species were rare. Importantly, our results also support the notion that detailed topographic metrics can be considered as a surrogate for elusive climatic factors and the habitat’s condition. Hence, the study emphasises that the process of selecting predictor variables, especially topographic metrics, is one of key elements in developing Species Distribution Models for birds, even for those species which are not directly dependant on the topographic metrics.
... The resurgent block is ~ 4 x 5 km wide, and its edges are marked by a system of sub-vertical faults with NW-SE, NE-SW, and N-S strikes [e.g., Orsi et al. 1991, Tibaldi and Vezzoli 1998, Carlino 2012. Several other faulty systems cut the deposits in the other sectors of the island [de Vita et al. 2006, Nappi et al. 2010 (Figure 1b). This structural set- ting seems to result from the interplay between re- gional and local tectonics [Orsi et al. 1991 andAcocella andFuniciello 1999]. ...
We carried out a study of the structures of the volcanic island of Ischia by the analysis and interpretation of high-resolution aeromagnetic data and by a newly compiled inland gravity data set. The comparison between the vertical gradient of gravity data and pole-reduced magnetic data was performed through semblance analysis and highlighted a correspondence between the main magnetic and gravity highs over the lava and green tuff deposits (e.g., Punta Imperatore, Mt. Trippodi, Zaro, Mt. Rotaro, Mt. Epomeo). Our analysis also highlighted the simultaneous presence of a magnetic minimum and a gravimetric maximum in the central part of the island, mainly visible in the long-period components of the two data sets. This may be due to the existence of a partially demagnetized structure with positive density contrast, representing the island's igneous basement. The boundaries of the lava and tuffs deposits of the island were clearly pointed out by the maxima of the total horizontal gradient maps of magnetic and gravity data. Those maxima also show the position of several lineaments, in good agreement with the mapped faults of the island.
... La morfologia dell'isola d'Ischia è dominata dal M. Epomeo (787 m s.l.m.) situato in posizione centrale e dall'allineamento NE-SW di M. Vezzi -M. Cotto nel settore SE, la costa è caratterizzata da ripide scogliere e da versanti meno acclivi che immergono verso mare [Gillot et al., 1982;Vezzoli, 1988;Civetta et al., 1991;Orsi et al., 1991;1994;Tibaldi e Vezzoli, 2000;Piochi et al., 1999;Acocella and Funiciello, 2002;Nappi et al., 2010]. ...
Il monitoraggio tiltmetrico permette di osservare in continuo le variazioni di inclinazione del suolo in
aree vulcaniche con l’obiettivo di individuare eventuali precursori geofisici delle fasi eruttive e più in
generale, di studiare l’evoluzione del fenomeno dalla fase di inflation a quella di deflation. A tale scopo
vengono utilizzati quei sensori la cui risoluzione è dell’ordine della deformazione che ci si aspetta e la cui
tipologia è legata alle caratteristiche del sito da attrezzare [Dzurisin, 1992].
Il monitoraggio tiltmetrico, con l’utilizzo di sensori elettronici, gestito dall’Osservatorio Vesuviano
(che con il Decreto Legislativo n. 381 del 29 Settembre 1999 è diventato Sezione di Napoli dell’Istituto
Nazionale di Geofisica e Vulcanologia, OV-INGV) è iniziato nel 1991, con la realizzazione delle reti dei
Campi Flegrei e del Vesuvio [Aquino et al., 2006; Ricco et al., 2009].
I sensori utilizzati sono tiltmetri analogici di superficie (modello 702 Applied Geomechanics
Instruments - AGI) e da pozzo (modello 722 AGI) con trasduttore a bolla, che misurano le variazioni di
inclinazione del suolo con una risoluzione di 0.1 μradianti lungo le due direzioni ortogonali X e Y, corredati
da un sensore termico [AGI, 1988]. Il passo di campionamento è di 5 minuti (dall’inizio del 2016 è passato
ad 1 minuto).
Questi sensori sono fortemente influenzati da fattori ambientali, come le variazioni di temperatura e
pressione, le precipitazioni e le variazioni della falda acquifera, che possono mascherare la reale
deformazione misurata.
Per minimizzare questi disturbi, i sensori analogici da superficie sono stati installati in ambienti
sotterranei come gallerie o in pozzetti profondi almeno 2 metri, mentre quelli analogici da pozzo sono stati
installati in fori profondi circa 10 metri.
Successivamente sono stati installati sensori biassiali digitali di ultima generazione modello Lily self-
Leveling Borehole tiltmeter (della Jewell Instruments. ex AGI) [AGI, 2005] con risoluzione inferiore a 5
nradianti e passo di campionamento di 1 minuto.
