A B S T R A C TThis work represents a case study concerning the application of reflection seismic imaging methods in the context of geothermal exploration. Our goal is to obtain accurate structural images of a geothermal active area in southern Tuscany. These images will be required in subsequent studies as the input for geological model building and numerical simulation of the heat transport and fluid flow. The target region exhibits great geologic complexity, including strong velocity contrasts, lateral nearsurface inhomogeneities, fracture zones, and significant topography. Those features are typical for a volcanic hard-rock environment and pose significant challenges to conventional seismic imaging methodology. Therefore, we apply a sophisticated and robust depth imaging workflow to previously acquired surface seismic data. Within our workflow, we focus on estimating the seismic velocities of the predominant rock units and subsequently carry out Kirchhoff pre-stack depth migration and Fresnel volume migration to obtain high-resolution images of the subsurface. Our results demonstrate that the applied methodology provides a valueable tool for imaging in a complex environment such as a volcano-geothermal area. In detail, the resulting reflector images show the main horizons that delineate the Tuscan sedimentary rocks in the target region. The images from standard Kirchhoff migration can be significantly enhanced by utilizing Fresnel volume migration, which eliminates migration artefacts and provides a better result. Moreover, we obtain the migration velocities and depths for an important regional reflector, known as the K-horizon, which is of major interest for geothermal characterization.

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Geothermal reservoirs can be characterized by the analysis of heat transport and fluid migration throughout the target rock volume. A hydrothermal simulation which provides insights into these processes, however, first requires detailed knowledge of the structural parameters of the reservoir. Those can be obtained from reflection seismic measurements. For this purpose, we apply two different prestack depth migration methods, namely the familiar Kirchhoff Prestack Depth Migration (KPSDM) and the recently developed Fresnel Volume Migration (FVM) on five seismic reflection profiles in a target region in Southern Tuscany, Italy. The resulting migrated images capture the important reflectors of the target region and provide a good insight in the potential extend of the geothermal reservoir. Moreover, we demonstrate that FVM produces cleaner images than KPSDM due to its "intelligent" aperture limitation. The obtained results provide the structural base on which a hydrothermal evaluation will be performed.

<p>Two hazardous storms, Christina (January 2014) and Leslie (October 2018), destructively affected the coast of Portugal and generated extreme sea level variations. We analyzed both the sea-level and meteorological data, and performed numerical simulations to examine the observed wave-induced coastal hazard and identify the background harbor resonances at each port. The results revealed that the sea-level variation is affected by the combined effect of low-frequency sea level rise (surges) and high-frequency (HF) waves. For the 2014 event, we found that wind was the main source of the HF sea surface variation, which excited the background harbor resonance. For the 2018 event, storm surges were significantly stronger and HF amplitudes were mostly induced by the movement of a pressure jump, leading to a meteotsunami formation. Commonly, wind is considered as a principal factor of the storm-generated HF waves, but we show herein  that the atmospheric pressure jump can play an important role in their formation through meteotsunami. The latter, when combined to a storm surge, can cause serious impact on the threatened coastal areas. </p>