Extensional faults in Southern Calabria (Italy) have been widely studied for their capability of generating high magnitude earthquakes (M-w 7-7.2). An example is the historical seismic sequence occurred in 1783, which caused numerous fatalities near the villages located along the longest faults of this region: the Cittanova and the Serre faults. In this work, we estimated the seismic potential of these two faults by a kinematic block modelling approach using GNSS data of both campaign points and permanent stations. Our results indicate that both faults are accommodating the recognized extensional velocity gradient (similar to 1 mm yr(-1)) by long-term slip rates (similar to 2 mm yr(-1)). To estimate the back slip distribution and the interseismic coupling degree of the Cittanova and Serre faults, we discretized these by a triangular dislocation elements mesh. This approach has allowed us to distinguish the fault areas where elastic seismic rupture is more likely to happen from those affected by aseismic creeping behaviour. The obtained results show that the highest values of coupling are located near the shallow portion of the fault planes and near the southern tip of the Cittanova fault. We therefore estimated a set of possible rupture scenarios finding that the Southern Calabria domain is accumulating an interseismic moment rate at most equal to 2.16 x 10(16) Nm yr(-1), the equivalent of an earthquake of M-w 4.86 for each year.

The field trip focuses on the Quaternary tectonic structure of the Campanian-Lucanian Apennines. This area is responsible for some of the most destructive southern Apennine earthquakes, which were studied within the context of a PRIN-2017 project referred to as MUSE-4D, that stays for " Overtime tectonic, dynamic and rheologic control on destructive multiple seismic events- Special Italian Faults & Earthquakes: from real 4D cases to models". Part of the project focuses on two M7-class multi-event Special EarthQuakes (SEQs): Irpinia 1980 and Basilicata 1857, which released similar cumulate magnitudes in time lapses variable from few seconds (1980) to few minutes (1857). These events and their host structures were analysed in innovative overtime (Quaternary and active) and multi-scale (local to regional) approaches within the project context. The geometry, kinematics, and structural style of the potentially seismogenic sources of these events are still questioned in the literature. A full constraint of their surface setting is fundamental to reducing the number of variables in assessing the extensional tectonics of the area and in the 3D fault model building. The three-days field trip is finalized to visit both the largely agreed and the controversial fault exposures to discuss them among the geo-scientific community.

QUIN database integrates and organizes structural-geological information from published and unpublished sources to constrain deformation in seismotectonic studies. The initial release, QUIN1.0, comprised 3,339 Fault Striation Pairs, mapped on 445 sites exposed along the Quaternary faults of central Italy. The present Data Descriptor introduces the QUIN 2.0 release, which includes 4,297 Fault Striation Pairs on 738 Structural Sites from southern Italy. The newly investigated faults span ~500 km along the Apennines chain, with strikes transitioning from ~SE to ~SW and comprehensively details Fault Striation Pairs’ location, attitude, kinematics, and deformation axes. Additionally, it offers a shapefile of the fault traces hosting the data. The QUIN 2.0 release offers a significant geographic extension to the QUIN 1.0, with comprehensive description of local geometric-kinematic complexities of the regional pattern. The QUIN data may be especially relevant for constraining intra-Apennine potential seismogenic deformation patterns, where earthquake data only offer scattered or incomplete information. QUIN’s data will support studies aimed at enhancing geological understanding, hazard assessment and comprehension of fault rupture propagation and barriers.

<p>Deformation effects on surface due to active geological processes are several (e.g., uplift, subsidence and shear discontinuities), these are strictly related to the source parameters and to the geomechanical properties of the surrounding rocks. In the last 20 years, remote sensing represents a key tool for the evaluation and monitoring of the natural hazards. Disasters occur when hazard and vulnerability match.</p> <p>The risk is proportional to the magnitude of the hazards and the vulnerability of the involved population. Among the deformation monitoring systems, photogrammetry technique from Unmanned Aerial Vehicles (UAVs) is spreading thanks to the high efficiency in data acquisition (time span, resource, and operators), low cost and the capability to acquire high-resolution images. The use of UAVs in contexts of natural hazard presents three main steps for risk assessment: pre-post event data acquisition, emergency support and monitoring. The mud volcano of Santa Barbara (Municipality of Caltanissetta, Sicily, Italy) represents a potentially dangerous site. On 11th August 2008 a paroxysmal event caused serious damage to infrastructures for a range of about 2 km. The main clues of mud volcano paroxysmal events are the uplift and the development of structural features with dimensions ranging from centimetre to decimetre. Here we present a methodology for monitoring of deformation processes that may be precursors of the mud volcano unrest period. This methodology is based on: i) the data collection, ii) the Structure from Motion (SfM) processing chain and iii) the M3C2-PM algorithm for the comparison between point clouds and uncertainty analysis with a statistical approach. This methodology is useful to detect hazard precursors by monitoring of deformation processes with centimetre precision and a temporal frequency of 1 - 2 months. Precision maps and the M3C2-PM algorithm are used to determine surface variations. The statistical analysis allows us to verify i) the uncertainty between the different surveys ii) the spatial variability of the accuracy; iii) the quality of the georeferencing of the surveys based on the number of GCPs (ground control points).</p>

<p>Since the Late Pliocene - Early Pleistocene, the Calabrian Arc (southern Italy) is affected by extensional and transcurrent tectonic superimposed on the previous collisional context. Various seismogenic sources have been proposed over time to explain such a complex structural framework, but the topic is still matter of debate. </p> <p>In this work we apply a multidisciplinary approach, concerning Geology, Geomorphology, Seismology and Geodesy, to develop a reliable 3D model of the Cittanova and Serre faults. These faults are considered the causative faults for the 1783 seismic sequence (M 6.5-7) as proposed by <strong>Jacques et alii (2001)</strong>. We used CROP data to investigate the crustal architecture of the area and to constrain the geometry at depth of the major structures. through two schematic geological sections orthogonal to these two faults. The shallow geometric patterns of the Cittanova and Serre faults, were verified trough geological, geomorphological and structural field data. Earthquakes hypocentres were analysed and relocated in order to recognize possible cluster alignments useful to constrain the faults geometry at depth. The high-density level of crustal seismicity attests that this domain is seismically active, between 0 km and 23 km and it concentrates along the main faults. To compute the strain and velocity field of the area (time span of the last 20 years) we measured the IGM95  (Instituto Geografico Militare) benchmarks and processed several GNSS permanent stations belonging to the RING Network (http://ring.gm.ingv.it) and TopNETlive Italy Network (https://rtk.topnetlive.com/italy/networks/topnet-live-italy) using GipsyX 1.5 Strain inversion (performed through grid_strain 2D software) allowed us to define a predominant WNW-ESE extensional deformation, in agreement with previous studies). Combining all previous data, we built for the first time a reliable 3D model of the Cittanova and Serre fault planes, that are consistent with:  i) fault magnitude/size empirical relations (Magnitude vs rupture Area, Magnitude vs fault length; ii) geological and geomorphological field observation (fault attitude and kinematic), iii) seismological and geodetic data. Results show that our model is compatible with the seismogenic sources of the 1783 seismic sequence.</p>

SUMMARY The south-eastern sector of the Mount Etna, Italy, is characterized by numerous active faults, in particular the Belpasso–Ognina lineament, the Tremestieri–San Gregorio–Acitrezza fault, the Trecastagni fault and the Fiandaca–Nizzeti fault including the Timpe Fault System. Their activity is the result of both volcanism and tectonics. Here, we analyse the ground deformation occurred from 2016 to 2019 across those active faults by using the GNSS data acquired at 22 permanent stations and 35 campaign points observed by the Etna Observatory (INGV) and by the University of Catania. We also use the time-series of line of sight displacement of permanent scatterers SENTINEL-1 A-DInSAR obtained by using the P-SBAS tool of the ESA GEP-TEP (Geohazards Thematic Exploitation Platform) service. We discriminate the contributions of the regional tectonic strain, the inflations, the deflations of the volcano and the gravitational sliding in order to analyse the deformation along the faults of the south-eastern flank of Etna. The shallow and destructive Mw = 4.9 earthquake of 2018 December 26 occurred within the studied area two days after a dyke intrusion, that propagated beneath the centre of the volcano accompanied by a short eruption. Both GNSS and InSAR time-series document well those events and allow to investigate the post-seismic sliding across the faults of south-eastern flank. We analyse the slow slip events (SSE) that are observed in the GNSS and InSAR time-series in the vicinity of the Acitrezza fault. We quantify and discuss the tectonic origin of the Belpasso–Ognina lineament that we interpreted as a tear fault.

<p>The geodynamic framework of Mount Etna volcano (Italy) is characterised by two superimposed tectonic domains: a compressional one, oriented N-S, and an extensional one, oriented approximately WNW-ESE. The combination of these two domains and the volcano activity, has generated a complex system of faults prevalently on the eastern flank of the volcano. The eastern flank is the most active area of the volcano in terms of deformation and seismicity. The velocities there are at least one order of magnitude greater than in the rest of the volcano flanks due to the eastward sliding of the eastern flank.</p> <p>The monitoring and analysis of the acceleration occurring on the eastern flank of Mount Etna is the keystone to understand the volcano-tectonic dynamics that, apart from the tectonic and magmatic processes, involves the instability of this flank in a densely inhabited area.</p> <p>In order to monitor the deformation, Istituto Nazionale Geofisica e Vulcanologia – Osservatorio Etneo (INGV-OE) and the GeoDynamic & GeoMatic Laboratory of the University of Catania integrate GNSS and InSAR products with twofold objective: to characterize the dynamics of the area and to analyse the deformation transients, this last in view of a possible use in the framework of an alert system.</p> <p>Here, we analyse the ground deformation that occurred between 2016 and 2019 across the faults of the south-eastern flank of Mount Etna. On the south-eastern flank the deformation is accommodated by several faults which have different kinematics and behaviours. We discriminate the deformation transient and the activity of the Belpasso-Ognina lineament, Tremestieri, Trecastagni, San Gregorio-Acitrezza, Linera, Nizzeti and Fiandaca faults. The latter generated the 26 December 2018 earthquake, two days after the eruption of 24 December, which induced a clear post seismic deformation, detected by GNSS and InSAR data. In particular, we discriminate the deformation occurred along the San Gregorio-Acitrezza fault, which is accommodated by the Nizzeti fault, and we analyse the post seismic deformation along the Linera fault. We analyse the Slow Slip Events (SSE) that are observed in the GNSS and InSAR time series in the vicinity of the Acitrezza fault and we quantify and discuss the tectonic origin of the Belpasso-Ognina lineament that we interpreted as a tear fault.</p>

Active normal faulting and uplifting, consistent with a WNW-ESE-oriented regional extension, dominate the Quaternary tectonics of the southern Calabrian Arc. The main tectonic structures of this extensional domain are considered to be the source of numerous historical and recent strong earthquakes, among which the 1783 seismic sequence (M 6.5–7) was one of the most destructive earthquakes ever recorded in Southern Italy. Previous works on the seismotectonic of the Calabrian Arc indicate a disagreement on the attitude (E-dipping vs W-dipping) of the main seismogenic sources slicing across southern Calabria, whereby the seismotectonic framework is still debated. Following a multidisciplinary approach, based on morpho-structural and seismological data, the geometry at depth of the most reliable sources (i.e., Cittanova and Serre faults) was first modelled in a 3D environment to retrieve information about their seismic potential. The GNSS data from the permanent stations of RING/RDN and TopNETlive Italy networks have been processed in order to estimate the velocity field affecting this area. Then, data inversion allowed us to document a predominant WNW-ESE active extensional strain orthogonally to the modelled faults, consistent with the regional dynamics. The reliability of the model was tested using empirical relationships and fault response modelling simulation. Furthermore, slip tendency analysis revealed the propensity to slip of the modelled planes by applying a remote stress state derived from the kinematic-structural survey on fault planes.

The survey and structural analysis of surface coseismic ruptures are essential tools for characterizing seismogenic structures. In this work, a procedure to survey coseismic ruptures using satellite interferometric synthetic aperture radar (InSAR) data, directing the survey using Unmanned Aerial Vehicles (UAV), is proposed together with a field validation of the results. The Sentinel-1 A/B Interferometric Wide (IW) Swath TOPSAR mode offers the possibility of acquiring images with a short revisit time. This huge amount of open data is extremely useful for geohazards monitoring, such as for earthquakes. Interferograms show the deformation field associated with earthquakes. Phase discontinuities appearing on wrapped interferograms or loss-of-coherence areas could represent small ground displacements associated with the fault’s ruptures. Low-altitude flight platforms such as UAV permit the acquisition of high resolution images and generate 3D spatial geolocalized clouds of data with centimeter-level accuracy. The generated topography maps and orthomosaic images are the direct products of this technology, allowing the possibility of analyzing geological structures from many viewpoints. We present two case studies. The first one is relative to the 2016 central Italian earthquakes, astride which the InSAR outcomes highlighted quite accurately the field displacement of extensional faults in the Mt. Vettore–M. Bove area. Here, the geological effect of the earthquake is represented by more than 35 km of ground ruptures with a complex pattern composed by subparallel and overlapping synthetic and antithetic fault splays. The second case is relative to the Mt. Etna earthquake of 26 December 2018, following which several ground ruptures were detected. The analysis of the unwrapped phase and the application of edge detector filtering and other discontinuity enhancers allowed the identification of a complex pattern of ground ruptures. In the Pennisi and Fiandaca areas different generation of ruptures can be distinguished, while previously unknown ruptures pertaining to the Acireale and Ragalna faults can be identify and analyzed.

The upwelling of fluids, subject to overpressure, along with discontinuities in the subsoil, causes the formation of geological structures known as mud volcanoes. These structures, very widespread in the world and in some cases located near inhabited centers, can represent a considerable risk factor for the population, as they can give rise to paroxysmal eruptions, even very violent. The assessment of the characteristics and structure of the subsoil of the areas affected by this phenomenon can prove to be a useful tool for risk mitigation. Non-invasive geophysical surveys were carried out in the area of the active cone of the Santa Barbara mud volcano in order to obtain a 3D characterization of the subsoil. Through the processing and integration of data derived from active and passive seismic surveys was obtained, a 3D model showing the seismostratigraphic subsoil structure. The electrical resistivity tomography surveys provided results comparable to those obtained from seismic surveys and supplied information on the perimetral areas of the mud volcano. The information obtained is useful to study the boundary conditions that influence short-scale activity. Furthermore, this study seeks to evaluate the possibility of using the proposed methodological approach for monitoring the variations that occur over time in the areas affected by mud volcanoes phenomenon.

Mount Etna is located on eastern Sicily on the border of the collision zone between the Eurasia and Nubia plate. The regional geodynamic framework is characterized by two superimposed regional tectonic domains: a compressional one oriented N-S and an extensional one oriented approximately WNW-ESE. These two domains, together with the volcano-tectonic one, generated a tectonic system which is unique in the world. It exhibits a complex system of faults prevalently on the eastern flank of the volcano, which is the most complicated in terms of interaction between the tectonic, volcano and gravitational processes. The eastern flank of Mount Etna is the most active area of the volcano in terms of deformation and seismicity, because the deformation rates are at least one order of magnitude greater than the surrounding area, due to the eastwards sliding of this flank. The monitoring and analysis of the high deformation occurring on the eastern flank of Mount Etna is the keystone for understanding the volcano-tectonic dynamics that, apart from the tectonic and volcanic processes, it is paramount relevant because involves the instability of this flank in a densely inhabited area. In this context the Istituto Nazionale di Geofisica e Vulcanologia – Osservatorio Etneo (INGV-OE) created one of the most sophisticated and complete monitoring networks in the world in terms of number of multi-disciplinary station (seismic, geodetic, geochemistry). Since 2014, the GeoDynamic & GeoMatic Laboratory (GD&GM-LAB) of the University of Catania started to create many GNSS sub networks, belonging to the UNICT-Net, in order to determine the offsets occurring on the blocks of each fault of the eastern flank. In order to have a complete analysis of deformation, INGV-OE and the GD&GM-LAB started to consider this area as an “open-air laboratory” where integrate GNSS and InSAR data with the twofold objective: to characterize the dynamic of this area for contributing to the volcanic hazard assessment and to identify precursor phenomena on shear structures analysing the relationship between kinematics, dynamics and volcano processes in the frame of the ATTEMPT INGV project.

Summary The Santa Barbara mud volcano area (Sicily-Italy), located in the Caltanissetta basin, represents one of the most important areas characterized by sedimentary volcanism phenomena, as evidenced by paroxysmal events that occurred in the area. Mud volcanism is generated by the presence of pressurized gases in the subsurface. These gases tend to emerge at the surface using preferential upwelling pathways linked to the presence of structural discontinuities. In this study the authors show the results of geophysical field surveys performed in the Santa Barbara mud volcano area (Sicily-Italy), to identify shape and size of the mud reservoir. Integration of passive and active seismic surveys allowed to obtain a 3D reconstruction of the mud volcano reservoir.

A multidisciplinary work integrating structural, geodetic and seismological data was performed in the Catanzaro Trough (central Calabria, Italy) to define the seismotectonic setting of this area. The Catanzaro Trough is a structural depression transversal to the Calabrian Arc, lying in-between two longitudinal grabens: the Crati Basin to the north and the Mesima Basin to the south. The investigated area experienced some of the strongest historical earthquakes of Italy, whose seismogenic sources are still not well defined. We investigated and mapped the major WSW–ENE to WNW–ESE trending normal-oblique Lamezia-Catanzaro Fault System, bounding to the north the Catanzaro Trough. Morphotectonic data reveal that some fault segments have recently been reactivated since they have displaced upper Pleistocene deposits showing typical geomorphic features associated with active normal fault scarps such as triangular and trapezoidal facets, and displaced alluvial fans. The analysis of instrumental seismicity indicates that some clusters of earthquakes have nucleated on the Lamezia-Catanzaro Fault System. In addition, focal mechanisms indicate the prevalence of left-lateral kinematics on E–W roughly oriented fault plains. GPS data confirm that slow left-lateral motion occurs along this fault system. Minor north-dipping normal faults were also mapped in the southern side of the Catanzaro Trough. They show eroded fault scarps along which weak seismic activity and negligible geodetic motion occur. Our study highlights that the Catanzaro Trough is a poliphased Plio-Quaternary extensional basin developed early as a half-graben in the frame of the tear-faulting occurring at the northern edge of the subducting Ionian slab. In this context, the strike-slip motion contributes to the longitudinal segmentation of the Calabrian Arc. In addition, the high number of seismic events evidenced by the instrumental seismicity, the macroseismic intensity distribution of the historical earthquakes and the scaling laws relating to earthquakes and seismogenic faults support the hypothesis that the Lamezia-Catanzaro Fault System may have been responsible for the historical earthquakes since it is capable of triggering earthquakes with magnitude up to 6.9.

Recently, attention has been claimed to the conservation- restoration of Cultural Heritage. This paper is focused on the creation of thematic maps which incorporate attribute data from the building materials to the type of stone damage. This approach would be a contribution for monitoring the knowledge of stone deterioration and facilitating the information collection in the optic of the most appropriate sustainable monument preservation measures. For this purpose, in the framework of the Italian National Research Program “Advanced Green Materials for Cultural Heritage”, eight historical buildings located in the Catania city center (Sicily) have been selected and the geodatabase AGM (Advanced Green Materials) has been created to archive a lot of data obtained in this study. The final pilot system allows to: i) import and export different graphical and alphanumerical data more than one coordinate systems (cadastral data); ii) generate new thematic maps by querying on the database (map of alteration processes in relation to the type and exposure of the elevation); iii) relate to each other different physical or logical data (processes of natural and anthropogenic environmental pollution); iv) define, in a parametrical manner, queries and entities properties directly from the user interface (extract mathematical and analytical models of the interrogated processes). SfM (Structure from Motion) survey techniques and automatic digital photogrammetry systems have been used to measure the geometries of the architectural elements, and a database-GIS (Geographic Information System) has been planned in order to storage and process the associated attribute data of both building materials and decay forms.The result was the development of a powerful tool for managing all the historical buildings information.

Active geological processes often generate a ground surface response such as uplift, subsidence and faulting/fracturing. Nowadays remote sensing represents a key tool for the evaluation and monitoring of natural hazards. The use of unmanned aerial vehicles (UAVs) in relation to observations of natural hazards encompasses three main stages: pre- and post-event data acquisition, monitoring, and risk assessment. The mud volcano of Santa Barbara (Municipality of Caltanissetta, Italy) represents a dangerous site because on 11 August 2008 a paroxysmal event caused serious damage to infrastructures within a range of about 2 km. The main precursors to mud volcano paroxysmal events are uplift and the development of structural features with dimensions ranging from centimeters to decimeters. Here we present a methodology for monitoring deformation processes that may be precursory to paroxysmal events at the Santa Barbara mud volcano. This methodology is based on (i) the data collection, (ii) the structure from motion (SfM) processing chain and (iii) the M3C2-PM algorithm for the comparison between point clouds and uncertainty analysis with a statistical approach. The objective of this methodology is to detect precursory activity by monitoring deformation processes with centimeter-scale precision and a temporal frequency of 1–2 months.

The 2018 December 26th earthquake (M-w = 4.9) at the south-eastern slope of Mt. Etna provides new insights for improving the knowledge of the kinematics of the eastern flank of the volcano. The earthquake was preceded by a seismic swarm on the upper southern-western sector of the volcano and by a short eruptive event in the summit area. The associated crustal deformation triggered seismic reactivation of tectonic structures in the eastern flank of the volcano. The seismogenic source has been localized along one of the segments cutting the south-eastern slope the volcanic edifice, the NW-SE trending Fiandaca Fault, one of the most active shear zone belonging to the upslope extension of the Timpe fault system. In the last centuries, all these faults have been the source of very shallow, low magnitude, but destructive earthquakes. In order to determine the response of the unstable eastern flank of Mt. Etna to the volcano-tectonic events, we applied a multidisciplinary approach based on: i) analysis of historical and instrumental seismicity; ii) mapping of coseismic fracturing, iii) analysis of GPS and InSAR data. This study allows to better define the seismotectonic framework of the shear zone occurring in the eastern flank of Mt. Etna, framing it in the seismogenic belt extending as far as the Ionian offshore.

The eastern slope of Mt. Etna is characterised by shallow seismicity originating from normal-oblique faulting, Timpe Fault System, related to WNW-ESE regional extension. Recent research has demonstrated that in the fault population of Mt. Etna's eastern flank the minimum earthquake magnitude that will have a ground rupture effect is ca. 2.5. This system is characterised by high frequency seismic activity, due to thinned seismogenic crustal layer. This characteristic, together with the high density of the fault segments, does not always for identification of the segments responsible for the earthquake. The earthquakes, affecting the medium-lower eastern flank, have been historically reconstructed by macroseismic analysis and reported in a macroseismic database, and in recent decades by instrumental seismic registration, which provide the seismological parameters capable of evaluating focal mechanism, hypocentre and relative algorithms related to geometric parameters which control the growth of fault segments. In this paper, we present a methodology to evaluate the age of the rapid exhumation of the free-face fault plane of the NNW-SSE oriented normal fault segment named S. Tecla (Timpe Fault System). It consists of the measurement of the thalli species (Lichenometry method) in order to evaluate the parameters which characterise their growth. The seismic history of the S. Tecla Fault indicates eight certain events from 1865 to 2005 with 3.4 divided by 4.7 Magnitude (De Guidi a al., 2012 and reference therein). We found evidence of two different recent rapid vertical deformation events at the base of the S. Tecla fault escarpment, the oldest 20 m long and 0.25 m in height, and the youngest with a 0.02 m high nude surface exposed. We have observed that there are thalli of Xanthoparmelia conspersa (Ehrh. Ex Ach.) Hale, colonizing part of the nude surface on the escarpment. The results highlight that the oldest thalli was dated at 43.7 years old, showing that rapid vertical deformation generated the surface where the thalli, after 4 years, took root. The displacement of this surface could be related to the seismic events occurring on 3rd August 1973 (3.8 M) in S. M. Ammalati area probably accompanied by intense post seismic deformation. The second and last event could be attributable to a 3.1 M seismic event occurring on 25th September 2014 (ISIDe, 2016).

13 morPhometrIC, geodetIC and geoPhYsICal surveYs of mud volCanoes: evIdenCe of teCtonIC Control In the sICIlIan CollIsIonal Belt G. De Guidi1, F. Carnemolla1, G. Barreca1, F. Brighenti1, C. Monaco1, A. Di Pietro1, S. Marchese1, D. Messina1, L. Scarfì2, A. Vecchio1 1 Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Sezione di Scienze della Terra, Università di Catania, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, Catania, Italy