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The San Bartolo lava flow field is the most recent flank eruption occurred at Stromboli volcano about 2 ka ago on the NE flank of the island. Despite its importance in being the most recent example of flank activity outside the barren Sciara del Fuoco slope, where the recent activity concentrated, the eruption duration, its volume, and the sequence of events has not yet been reconstructed. In this paper, we present a new survey of the lava flow field, carried out both on the field and photogrammetric and LIDAR surveys from UASs, in order to estimate the erupted lava volume and to reconstruct the sequence of events and infer a possible duration and impact of the eruption. The analysis of the surveys allowed us to verify the contact with previous lava flow fields, allowing a more precise lateral extension of the lava delta along the coast, as well as an estimation of the thickness and volume, at least for the subaerial portion of the lava flow field. The morphology analysis of the lava flow field allowed us to recognize structures suggesting inflation and then stationing of the lava flow fronts, features indicating a long-lasting eruption and a complex interaction with the sea. Our results can provide a useful scenario should a flank eruption occur in the future, a possibility that was close to happening in 1998, when the ground deformation stations revealed a lateral intrusion in the shallow supply system of the volcano.

Current EO satellite missions providing imagery in the VIS- TIR region at high spatial resolution offer the possibility to estimate a number of important parameters to monitor volcanic activities at worldwide level. Therefore, space missions contribute in understanding the ongoing phenomena to mitigate the volcanic risk when population and infrastructures are exposed. New hyperspectral and thermal missions which could provide images at high spatial and temporal resolution are under study in cooperation between Space Agencies (NASA, ASI, ESA etc.) and hopefully will improve the monitoring capabilities of active volcanoes in highly populated areas. In the present work we describe several results obtained in the last years by EO satellite missions for the volcanic risk. While the satellite data provide a wide description of scenes, in situ and proximal measurements are crucial to retrieve gas emissions and analyze surface characteristics at very high spatial resolution. Data acquired from drones (UAV) and thermal cameras in volcanic areas are presented and discussed. Moreover, this work shows the need of validation process for satellite products comparing with measurements collected during field campaigns.

Geothermal and volcanic systems are prone to gravity-induced slope instability at different scales. Endogenous magmatic, hydrothermal and seismic forcings can significantly modify rock mass rheology and perturb the local stress field and gravitational equilibrium, inducing shallow or slope-scale processes. The island of Ischia, which is part of the Phlegrean Volcanic District (Italy), is a remarkable example of this kind of complex interacting system. This study focuses on monitoring the hydrothermal system located beneath the ongoing slope-scale deformation, which involves Mt Nuovo (the western part of Mt Epomeo) and is a complementary effect of the resurgence of an ancient caldera. Debris and rock avalanches have affected the slopes of this volcanic island, in response to the renewal of volcanic activity and caldera resurgence. Large parts of the corresponding mass-wasting deposits overlay the most active areas of the Ischia hydrothermal system, where ongoing slope-scale gravity-driven deformation owing to a mass rock creep (MRC) process is still evolving. To investigate possible relations between the perturbing shallow hydrothermal system and the MRC process, thermal monitoring of selected groups of fumarolic emissions located in several portions of the deforming sector has been carried out since 2008 on a monthly basis by means of direct (thermal probes) and remote sensing (IR-thermography) techniques. Thermal monitoring of specific fumaroles reveals a peculiar seasonal trend characterized by a delayed inverse correlation with rainy periods and a short-term pulsating response to dry stages. The fumaroles also appear spatially correlated to the presence of MRC-related structures involving volcanic slopes. According to the measured thermal data, a conceptual model of the thermal interactions within the Mt Nuovo slope is provided, framing the potential role of thermal actions in accelerating the deformation process. In this view, possible chain effects, owing to magmatic or hydrothermal renovation, are depicted, delineating the most severe multihazard scenario consisting of an accelerating evolution of the MRC process towards paroxysmal collapse.

The volcanic system of Ischia is characterized by an intense hydrothermal activity, documented since the early 16th century by the study of Iasolino (1588), which represents the first systematic analysis of the thermal springs of the island for therapeutic purposes. Later studies partially contributed to the enhancement of knowledge on the volcanic, hydrogeological and hydrothermal features of the island, highlighting the strong interaction between hydrothermal flowpaths and volcano-tectonic processes . The reconstruction of the hydrothermal system becomes, therefore, a fundamental element for territorial planning, not only in terms of management of the huge water and geothermal resource, but also and above all in a perspective of prevention and mitigation of volcanic risk. Thermal springs, fumaroles and clay deposits due to the hydrothermal alteration of volcanic products testifies for the existence of an active deep hydrothermal system. Commonly, the geochemical characterization of fluids and groundwater has been used for the definition of the origin and structure of hydrothermal systems, when hydrogeological information is incomplete. However, volcanic hydrothermal systems, such as that characterizes the island of Ischia, are particularly difficult to analyze and outline, as the groundwater resources are the result of an articulated and dynamic interaction among meteoric water, sea water and fluids of deep origin. In such cases, the need for an interdisciplinary approach is evident, involving knowledge and research methods ranging from geology to volcanology, geophysics, geochemistry and hydrogeology. With particular reference to the functional and structural representation of the geothermal system of the island of Ischia and the resulting correlations with the volcano-tectonic processes, the examination of previous information highlights the need to update and improve the knowledge on groundwater hydrodynamics and mineralization processes.Therefore, this study represents the result of a strong interdisciplinary action that, starting from the design and implementation of a database on the existing geological/volcanological and hydrogeological information, contributes to highlight the critical issues, defines an operating scheme of the hydro-geo-thermal system of the island of Ischia, and aims at upgrade its hydrogeological, geochemical and volcanic monitoring system, in order to contribute to the mitigation of natural risks.Moreover, this study well fits into the framework of the ongoing researches on volcanic hazard at Ischia and is integrated with the actions planned by the Italian Department of Civil Defense. The knowledge of groundwater dynamics and pathways is of fundamental importance for understanding the water/magma interaction processes in case of re-alimentation of the shallow magmatic system, and the assessment of the possibility of phreatic explosions occurrence.

During the field campaign held on June 2018 at Parco delle Biancane and Sasso Pisano areas, near Grosseto (Italy), we have measured the surface temperature using data acquired by different sensors at different spatial resolutions: Earth Observation (EO) data from the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS), Hyperspectral Thermal Emission Spectrometer (HyTES) airborne imaging data and thermal images acquired by the FlyBit drone. ECOSTRESS has five spectral bands in the range 8-12.5 μm and pixel size resolution (at nadir) of 69x38 m (2 pixels in cross track and 1 pixel in down track); HyTES is an airborne imaging spectrometer having 256 spectral channels in the range 7.5-12 μm and high spatial resolution (0.8 m for the June campaign); VUE PRO-R mounted on FlyBit drone acquires in the range 7.5-13.5 µm with a spatial resolution depending on the flight altitude (in this work the pixel size is about 0.25 m). In addition, the Sony Alpha 600 visible camera was mounted on the FlyBit drone to acquire a very high resolution optical images over the test site. Our goal is to test the possibility to integrate data at different observation scales and to use the proximal measurements to better understand the thermal structure of test sites, also related to the area morphology and to validate the methodology for estimating the surface temperature by using EO data.

The purpose of this study is to analyze the surface temperature and the distribution of thermal signatures on Tuscany’s geothermal districts using data obtained through three separate surveys via satellite and an unmanned aerial vehicle (UAV). The analysis considers the highest available spatial resolution ranging from hundreds of meters per pixel of the satellite thermal images and the tenths/hundreds of centimeters per pixel of the thermal images acquired by the UAV. The surface temperature maps obtained by satellite data acquired at suitable spatial resolution and the thermal measurements obtained by the thermal camera installed on the UAV were orthorectified and geocoded. This allowed, for example, following the evolution of thermal anomalies, which may represent a modification of the current state of the geothermal field and a possible hazard for both the population and industrial assets. Here, we show the results obtained in three field campaigns during which the simultaneous acquisition of Landsat 8 satellite and UAV (FlyBit octocopter, IDS, Rome, Italy) thermal data were analyzed. By removing the atmosphere contribution from Landsat 8 data, we have produced three surface temperature maps that are compared with the ground field measurements and the surface temperature maps elaborated by FLIR VUE PRO-R on the UAV.

On 21 August 2017, a shallow earthquake of Md 4.0 struck the CasamicciolaTerme 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.

Quiescent volcanoes dissipate a large part of their thermal energy through hot soils and ground degassing mainly in restricted areas called Diffuse Degassing Structures. La Solfatara crater represents the main spot of thermal release for the Campi Flegrei volcano (Italy) despite its reduced dimensions with regards to the whole caldera. The purpose of this study was to develop a method to measure thermal energy release extrapolating it from the ground surface temperature. We used imaging from thermal cameras at short distances (1 m) to obtain a mapping of areas with thermal anomalies and a measure of their temperatures. We built a conceptual model of the energy release from the ground to atmosphere, which well fits the experimental data taken in the La Solfatara crater. Using our model and data, we could estimate the average heat flux in a portion of the crater as q a v g = 220 ± 40 W / m 2 , compatible with other measurements in literature.

Sr-isotopic microanalysis has been performed on selected minerals from the Campi Flegrei caldera, together with Sr and Nd isotopic ratio determinations on bulk mineral and glass fractions. The aim was a better characterization of the chemically homogeneous, but isotopically distinct magmatic components which fed volcanic eruptions of the caldera over the past 5 ka, in order to enhance our knowledge about one of the most dangerous volcanoes on Earth. Information on the involved magmatic endmembers, unobtainable by analyzing the isotopic composition of whole rock samples and bulk mineral fractions, has been acquired through high-precision determination of 87 Sr/ 86 Sr on single crystals and microdrilled mineral powders. We focused our investigations on the products emplaced during the Astroni 6 eruption (4.23 cal ka BP), assumed representative of the expected event in case of renewed volcanic activity in the Campi Flegrei caldera. Data on single crystals and microdrilled mineral powders have been compared with Sr and Nd isotopic compositions of bulk mineral fractions from products emplaced during the whole Astroni activity, which included seven distinct eruptions. The 87 Sr/ 86 Sr ratios of single crystals and microdrilled mineral powders are in the 0.7060 to 0.7076 range, much wider than that of bulk mineral fractions, which range from 0.7066 to 0.7076. Moreover, the Sr isotopic ratios are inversely correlated to 143 Nd/ 144 Nd. The new data allow us to better define the magmatic endmembers involved in mingling/mixing processes that occurred prior to/during the Astroni activity. One magmatic endmember, characterized by average 87 Sr/ 86 Sr ratio of ~ 0.70750, was quite common in the past 15 ka activity of the Campi Flegrei caldera; the other, as evidenced by the isotopic composition of single feldspar and clinopyroxene crystals, is less enriched in radiogenic Sr ( 87 Sr/ 86 Sr ~ 0.70724). The latter is interpreted to represent a new magmatic component that entered the Campi Flegrei caldera feeding system in the past 5 ka, the previously recognized Astroni 6 component. However, diopside crystals in Astroni 6 are characterized by even lower 87 Sr/ 86 Sr, in the range of 0.7060–0.7068 and by the highest 143 Nd/ 144 Nd ratios measured in the products of Astroni activity. These diopsides may represent another common magmatic component, as they have been found in most of the Phlegrean Volcanic District products emplaced over the past 75 ka. These diopsides, crystallized in a mantle-derived mafic magma, were entrapped by the Astroni 6 magma during ascent, before it mingled/mixed with the more differentiated and enriched in radiogenic Sr resident magma, thus attaining an intermediate Sr-Nd isotopic fingerprint. These results have an important outcome on the understanding of the volcano behavior, as renewed activity can be triggered by the arrival of fresh magma in the feeding system that would mingle/mix with the resident magma. Such an event may be able to start an unrest phase at the volcano that could last for years or decades, perhaps culminating in a new eruption.