Underground fluid injection and extraction is able to change pore fluid pressure at depth and make faults unstable, due to friction-force reduction, with an increased possibility of triggering earthquakes. Studying the local seismicity, down to microearthquakes, and stress field in areas where such activities are developed are essential steps to discriminate between natural and induced events. In this context, the moment magnitude (M W) is a key-parameter to both evaluate the energy balance and the stress involved in earthquake rupture process and assess seismic hazard accurately. Here, we focus on the fast M W estimation of microearthquakes recorded around the underground gas storage of Collalto (Northeastern Italy) by a dedicated seismic monitoring network. The area of Montello-Collalto, where this industrial activity is carried out, is densely populated and characterized by relevant seismic hazard. We compute M W from the response spectra (SA) calculated at fixed periods (i.e., 1.0 and 0.3 s); we show that log (SA) and M W scale as 2/3 and extend our method to microseismicity by using response spectra at 0.1 s. We eventually estimate M W for 1659 events (0.4 ≤ M W ≤ 3.5) and find that M L and M W scale as 2/3 too. The discrepancy between these two magnitude scales affects both the Gutenberg-Richter parameters and completeness magnitude estimations; therefore, it has consequences when those quantities are used for physical interpretation. Our procedure shows to be efficient and suitable to be implemented within standard routine analyses of real-time monitoring and feed decision-making processes about plant management, such as the traffic light protocols.

<p>Since the discovery of widespread Salt and Gypsum deposits of the Mediterranean Sea in the early ’50s, a large number of scientists tried to unravel the mystery related to this huge deposition of evaporites. Evidence of the later so-called “Messinian Salinity Crisis” (MSC) are largely distributed all around the Mediterranean Basin and widely studied. Although gypsum deposits were recognized in some peripheral or marginal basins (e.g. Sorbas Basin in Spain, Northern Apennines in Italy), mechanism of their deposition and formation are still uncertain. Particularly, the so-called Gessoso-Solfifera formation (GS Fm) was recognized in the ’50s by Selli in several outcrops in Northern Apennines and it is nowadays well known and mapped in the on-shore outcrops.  A regional analysis in the Adriatic Sea is still incomplete, even though a large amount of data is available (2D multichannel seismic lines, boreholes, exploration reports). In the Adriatic Sea, the MSC event can be recognized in the 2D seismic lines as actual thin deposit (maximum GS Fm thickness of about 120 ms TWT) or Messinian erosional surface (MES). In both cases, a strong and clear reflector at the Pliocene base is picked and calibrated by the boreholes reaching its depth. Along the main part of the available seismic profiles it is sometimes very hard to ascribe this strong reflector to the MES or to the presence of a thin gypsum layer. <br>Calibration of 2D seismic lines with boreholes, also integrated by physical properties derived from geophysical well logs and core data) of the Plio-Quaternary sediments, allowed a detailed seismic facies analysis useful for this purpose. A structural map of the Plio-Quaternary base describes the Plio-Quaternary deformation that affected the study area mainly as Apennine foreland. The thickness map of the GS Fm describes the subsidence and the erosional effect occurred during the MSC. Both these maps are here presented as a first result of a regional study, that intends cover the whole Adria offshore.</p>

<p>The Adriatic basin represents one of several restricted basins located in the Mediterranean Area. It consists of the foreland of three different orogenic belts: the Dinarides to the East, active during the Eocene, the Southern Alps to the North, active since the Cretaceous time, and the Apennines to the West, active since the Paleogene. The Apennines had a primary role during the Messinian Salinity Crisis (MSC), conditioning the connection between the Adriatic basin, the Ionian basin, and the proto-Tyrrhenian basin. During the Messinian, the present Adriatic Sea was characterized by shallow water domains, where gypsum evaporites initially deposited and often successively incised or outcropped. </p><p>In the past 50 years, a massive dataset, composed of 2D multichannel seismic data and boreholes, was collected, covering almost the whole Adriatic basin in the Italian offshore. In this work, we interpreted the Plio-Quaternary base (PQb), based on available public datasets and on seismic profiles present in literature, which provided regional information from the northernmost Trieste Gulf (Northern Adriatic Sea) to the Otranto Channel (Southern Adriatic Sea). Here, we propose the PQb time-structural map, obtained by analyzing more than 600 seismic profiles. The PQb represents both the Messinian erosion and/or the top of the Messinian evaporites. It is characterized by a high-amplitude reflector, commonly called “horizon M” in the old literature. Principal findings concerning the Messinian event are summarized as below: </p><p>-The Northern Adriatic (Gulf of Trieste, Gulf of Venice, Po delta, Kvarner Area) reveals widespread channelized systems produced by the initial decrease of the sea level, followed by subaerial erosion, related to further sea level decrease. High-grade erosion involved the nearby Adriatic carbonate platform in the Croatian offshore, where deep valleys, filled with Last Messinian or post- Messinian sediments, cut through the limestones.</p><p>-The Central Adriatic (from the Po delta to the Gargano Promontory) displays a higher evaporites accumulation than the northern sector. Meanwhile, the Mid-Adriatic Ridge was already developing, along with the Apennine Chain, which was in a westernmost position. Erosional features in the deeper area are related to channelized systems, which followed the evaporites deposition. Meanwhile, also the Mid-Adriatic Ridge was affected by erosion.</p><p>-The Southern Adriatic (from the Gargano Promontory to the Otranto Channel) is characterized by the Mesozoic Apulia carbonate platform, covered by a thin Cenozoic sequence affected by subaerial erosion or non-deposition. The platform margin and the slope leading to the deepest South Adriatic basin, where a Messinian gypsum layer, also recorded in the Albanian and Croatian offshore, shows a lower level of upper erosion.</p><p>In general, we notice strongly variable thicknesses of the horizon M, which is related to submarine erosion (channels), subaerial erosion (discontinuous surfaces), non-deposition (possible unconformity), and tilting toward the surrounding chains (deepening horizons). In this work, we evaluate these different components from a regional point of view.  </p>

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