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The 2021 Tajogaite eruption was characterized by short precursors, lasting only eight days. The seismicity started on Sep. 11th with a westward and upward migration of hypocenters. Permanent GNSS stations started recording deformation of the island's western side, which reached more than 15 cm just before the eruption.After the eruption's onset, which occurred on September 19th, the deformation increased, reaching a maximum on September 22nd and later showing a nearly steady deflation trend in the following months. To better understand the dynamics of the eruption, we exploited a joint dataset of GNSS and Sentinel-SBAS time series along both ascending and descending orbits. To obtain the geometry of the causative source of the ground deformation, we combined the result of a preliminary non-linear inversion and the precise distribution of the seismicity. The resulting geometry is that of a twisted dike bending eastward.We realized a spatio-temporal inverse modelling to obtain the evolution of the causative source of the ground deformation. The inverse modelling has been realized using a 3D finite-element approach considering the island's topography.The main results we obtained are that we observe a correspondence between the magmatic intrusion and pre-eruptive seismicity; the ascent of the magma occurred along two different branches; the rheology of a previously identified ductile layer strongly affected the magma propagation process. Finally, we evidence an early shallow deformation which we interpret as the effect of ascending hydrothermal fluids.Our findings highlight the need for advanced modelling to understand pre-eruptive processes in basaltic volcanoes., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

In this work, we propose a multi-scale approach for modeling the ground deformation field of volcanic sources. The methodology is based on the use of Multiridge and ScalFun methods to analyze the elastic deformation fields by providing source information, such as the depth, the horizontal position, and its morphological features. This strategy is alternative with respect to the classical inverse approaches since it allows overcoming some aspects of the ambiguities related to the interpretation of DInSAR measurements. Indeed, the multi-scale method does not need a priori constraints on the model parameters to achieve an unambiguous solution. First, we argue on the general physical conditions so that the deformation field, generally represented by biharmonic functions, also satisfies Laplace’s equation and the law of homogeneity. This occurs in the case of sources with hydrostatic pressure-change embedded in an elastic half-space. In these conditions, the properties of harmonic and homogeneous functions can be employed to model the ground deformation fields using multi-scale procedures. Then, we demonstrate the soundness of the proposed approach through the application of Multiridge and ScalFun methods to synthetic tests. We analyze the fields generated by spherical, pipes- and sills-like sources and consider different model settings, as the layered half-space, the noisy, and the multi-source scenarios. For all these simulations, we achieve unconstrained information related to the source geometry with satisfying accuracy. Finally, in order to show the flexibility of the multi-scale approach in different volcanic environments, we use Multiridge and ScalFun methods for analyzing DInSAR measurements relevant to Uturuncu, Okmok, and Fernandina volcanoes, retrieving information about their volcanic systems. In the first case, we point out a transient source at a depth of 4.5 km b.s.l., which is activated during 2006–2007 together with the stable and well-known Altiplano Puna Magma Body (APMB); in the second one, we retrieve a concentrated body at a depth of 3.1 km b.s.l. during 2003–2004; and in the last case, we interpret the 2013 unrest episode as caused by a pipe-like source located at a depth of 1.7 km b.s.l.

The RETRACE-3D project (centRal italy EarThquakes integRAted Crustal model) focused on the revision of all the available geological and geophysical data in the area interested by the 2016-2018 seismic sequence of central Italy, with the final aim to reconstruct a reliable and consistent 3D geological model of that area. It is based on a collaboration, which was framed into a formal agreement, between Dipartimento della Protezione Civile (the Italian Civil Protection Department), Istituto di Geologia Ambientale e Geoingegneria, and Istituto per il Rilevamento Elettromagnetico of the Consiglio Nazionale delle Ricerche, Istituto Nazionale di Geofisica e Vulcanologia, and Istituto Superiore per la Protezione e la Ricerca Ambientale. The agreement purpose was to develop a project aimed at the geological and seismotectonic characterisation of the crustal volume hosting that seismic sequence. We present and discuss the approach, methodology and results of the project. The 3D geological model of the study area is developed in detail down to a depth of about 12 km, and extended to the Moho based on available regional-scale information. The model is available on the RETRACE-3D project website (www.retrace3d.it).

We are writing this comment because many aspects of the analysis presented by Nappi et al. (2018) are debatable. In particular, a major issue is relevant to the conclusion suggested by Nappi et al. (2018) about a seismogenic normal fault with northward dip; this finding is not grounded because the Authors do not really present a causative source model and, above all, their statement is clearly not consistent with the DInSAR, GPS and seismological measurements presented in the manuscript previously published by De Novellis et al. (2018). Moreover, we also report an evident error in the geologic map proposed by Nappi et al. (2018), see Figure 3 of their manuscript.

The Campi Flegrei and its offshore prolongation (Pozzuoli Bay) are a volcanic area dominated by a collapse caldera associated with the Neapolitan Yellow Tuff (NYT) eruption, occurred at ~15 ka BP, and by an intra-caldera resurgent dome. We present new insights into: a) the geometry and kinematics of faults formed inside the caldera, b) the architecture of the resurgent dome, and c) the relationship between the structural elements of the resurgent dome and ground deformations. This work is based on the integration of high- and ultra-high resolution seismic data, swath bathymetry data and ground deformation maps. The main results highlight that the NYT caldera, offshore, is characterized by an ellipsoidal shape, elongated towards the ESE direction, with axes of ~8 km and ~7 km. It is bounded by a ~6 km long and 1–2 km wide ring fault zone (RFZ) mainly consisting of an inward-dipping normal fault system and antithetic, outwarddipping, faults. The sedimentary fill of the caldera is up to 60 m thick, and can be divided into six units, characterized by different seismic facies, composition and depositional process.The inner-caldera resurgent dome, ~ 5 km in diameter, is limited by inner boundary of RFZ and consists in a broad antiformal structure with brittle deformation localized in an apical graben. The base of the resurgence corresponds to the thalweg of the Epitaffio valley in the western sector of the Pozzuoli Bay and the Bagnoli valley in the eastern one. The maximum cumulative uplift of the resurgent dome is ~180 m while its average uplift rate is ~ 9–12 mm/year, between 15.0–6.6 ka BP. A subsidence of ~10 m is suggested by the drowning of the infralittoral prograding wedge below the present-day storm wave base for the last 2 ka.The deformation velocity pattern of the Campi Flegrei displays a radial symmetry centered on the Pozzuoli harbor. It is possible to distinguish three almost-concentric sectors namely S1, S2, S3 with decreasing velocity from S1 (13-32 mm/year) to S3 (0.3-7.7 mm/year). The highest value (26-32 mm/year) is recorded at the Pozzuoli harbor. Sector S1 is bounded by a NE– SW-trending fault to the west and NW–SE faults to the east. The data suggests that this sector coincides with the resurgent dome of NYT caldera. The base of the latter corresponds to the faults bordering sector S1, and it can be correlated with the base of the resurgence recognized offshore. Sector S2 represents a narrow strip located between the base of the resurgence and the onland prolongation of the inner boundary of the RFZ.The results of our research provide new insights into the stratigraphic architecture and the shallow structure of the NYT collapse-caldera in the Pozzuoli Bay. Furthermore, they represent a base to reconstruct the entire onshore-offshore geometry of the inner-caldera resurgence and infer new constraints on the dynamics of the fluid flow system and magma source at depth.

In Plutarch’s De defectu oraculorum a mysterious voice announces to a ship’s helmsman that «the Great Pan is dead». This enigmatic legend gave rise to two different interpretations crossing the history of European literatures. The first, concerning ritualism and folklore, connects this episode to the death of vegetations’s God (Tammuz, Adonis) or of another demonic entity. According to the second, common in Christian authors, Pan is the same crucifix Jesus or, on the contrary, the paganism defeated by his death. Gabriele D’Annunzio overturns announcement’s meaning and proclaims that «the Great Pan is not dead».

We investigate the ground deformation pattern and the source geometry responsible of the 2016 Central Italy seismic sequence (CISS) by joint exploiting the Multisensors and Multiorbits satellite measurements (i.e. Sentinel-1 and ALOS 2) and the integration with the available geological/structural and seismological data. To this purpose we integrate these measurements in a physically-based optimization model scenario. We consider the new seismic sequence that struck Umbria-Marche Apennines (Central Italy) since the month of August 2016. This seismic sequence started with the Amatrice earthquake (MW 6.0) occurred on August 24th. This event nucleated along a SW dipping extensional lineament, called the Mt. Gorzano fault (e.g. Boncio et al., 2004), and caused 299 casualties and severe damages to buildings and historical monuments, devastating Amatrice itself, Accumoli and other surrounding small towns. During the following months, very numerous aftershocks have nucleated and the CISS has migrated northward (e.g. Tinti et al., 2016). On October 26th two intense events occurred with ML 5.4 and ML 5.9, respectively. Moreover, on October 30th the strongest event of the sequence occurred with MW 6.5 close to the small town of Norcia and nucleated along the Mt. Vettore extensional fault (e.g. Galadini & Galli, 2003). The involved area is still active and a lot of earthquake nucleate every day: up to now, the INGV seismic network has recorded more than 30000 events. Despite to the tectonic complexity of the 2016 CISS, we achieved a good determination/description of the ground deformation pattern thanks to the big amount of SAR data acquired by Sentinel-1 (ESA) and ALOS 2 (JAXA) satellites, characterized by small temporal baselines and from different orbits (ascending and descending orbits). In this way, we can analyse in greater detail the ground deformation pattern of the individual seismic events, also decomposing the vertical component and the east-west one. In this context SAR data are a fundamental tool to better understand the spatio-temporal evolution of 2016 CISS. In this context, the present study, benefiting from satellite and in situ information, will investigate, through a numerical optimization multiphysics approach, the most suitable geological scenario that governed the spatial and temporal evolution of the Amatrice-Norcia seismic sequence. References Boncio, P., Lavecchia, G., Milana, G., & Rozzi, B. (2004). "Seismogenesis in Central Apennines, Italy: an integrated analysis of minor earthquake sequences and structural data in the Amatrice-Campotosto area." Annals of Geophysics, vol. 47, issue 6, December 2004. Galadini, F., & Galli, P. (2003). "Paleoseismology of silent faults in the Central Apennines (Italy): the Mt. Vettore and Laga Mts. faults." Annals of Geophysics, vol. 46, issue 5, October 2003. Tinti, E., Scognamiglio, L., Michelini, A., & Cocco, M. (2016). "Slip heterogeneity and directivity of the ML 6.0, 2016, Amatrice earthquake estimated with rapid finite-fault inversion." Geophysical Research Letters, vol. 43, issue 20.

We investigate a large geodetic data set of interferometric synthetic aperture radar (InSAR) and GPS measurements to determine the source parameters for the three main shocks of the 2016 Central Italy earthquake sequence on 24 August and 26 and 30 October (M-w 6.1, 5.9, and 6.5, respectively). Our preferred model is consistent with the activation of four main coseismic asperities belonging to the SW dipping normal fault system associated with the Mount Gorzano-Mount VettoreMount Bove alignment. Additional slip, equivalent to a Mw similar to 6.1-6.2 earthquake, on a secondary (1) NE dipping antithetic fault and/or (2) on a WNW dipping low-angle fault in the hanging wall of the main system is required to better reproduce the complex deformation pattern associated with the greatest seismic event (the Mw 6.5 earthquake). The recognition of ancillary faults involved in the sequence suggests a complex interaction in the activated crustal volume between the main normal faults and the secondary structures and a partitioning of strain release.

We present the main activities and the most significant results that the Institute for Electromagnetic Sensing of the Environment (IREA) of the National Research Council (CNR) has retrieved within the framework of its collaboration with the Ministry of Economic Development (MiSE) - Directorate- General for Safety of Mining and Energy Activities National Mining Office for Hydrocarbons and Georesources (DGS-UNMIG). In particular, this agreement aims at detecting and monitoring surface deformation affecting the areas of particular interest for the DGS-UNMIG through space-borne Differential SAR (Synthetic Aperture Radar) Interferometry (DInSAR) analysis and multi-parameters and multi-physics modelling. The first ones provide information on the spatial distribution of the retrieved ground displacements and their temporal evolution, the second on the geological/geophysical processes that characterize the investigated areas. In this work, we present the preliminary results retrieved via interferometric analysis performed by exploiting SAR data acquired from the first (ERS-ENVISAT) and second (Sentinel-1) generation sensors over the Emilia-Romagna Region (North Italy) and the entire Italian Peninsula, respectively. Moreover, we performed a 3D geological-structural model of the Cavone site (Emilia-Romagna) and a 3D FEM (Finite Element Method) model for simulating the co-seismic dislocation of the M6.0 and M5.8 seismic events, which occurred on 20/05/2012 and 29/05/2012 over Emilia-Romagna region, respectively.

We investigate the ground deformation and source geometry of the 2016 Amatrice earthquake (Central Italy) by exploiting ALOS2 and Sentinel-1 coseismic differential interferometric synthetic aperture radar (DInSAR) measurements. They reveal two NNW-SSE striking surface deformation lobes, which could be the effect of two distinct faults or the rupture propagation of a single fault. We examine both cases through a single and a double dislocation planar source. Subsequently, we extend our analysis by applying a 3-D finite elements approach jointly exploiting DInSAR measurements and an independent, structurally constrained, 3-D fault model. This model is based on a double fault system including the two northern Gorzano and Redentore-Vettoretto faults (NGF and RVF) which merge into a single WSW dipping fault surface at the hypocentral depth (8 km). The retrieved best fit coseismic surface deformation pattern well supports the exploited structural model. The maximum displacements occur at 5-7 km depth, reaching 90 cm on the RVF footwall and 80 cm on the NGF hanging wall. The von Mises stress field confirms the retrieved seismogenic scenario.

On 24 August 2016, at 01:36 UTC¸ the intra-Apennine extensional fault system of Central Italy released a destructive earthquake (MW 6.0). It produced widespread damage and fatalities, killing about 300 people and severely destroying the town of Amatrice and surrounding villages. After few hours, the Amatrice earthquake was followed by a significant aftershock (MW 5.5), which nucleated 15 km NW-ward. The epicentral area of the seismic sequence extends in the NNW-SSE direction, for a length of about 25-30 km. It is located at the hanging-wall of the WSW-dipping Vettore-Gorzano active extensional fault system. During the days following the main shock, a significant number of Synthetic Aperture Radar (SAR) data have been acquired from different passes and angles by the L-band ALOS-2, C-band Sentinel-1 and X-band COSMO-SkyMed satellites. This allowed us to map in a very short time the co-seismic ground displacements through the Differential SAR Interferometry (DInSAR) technique, and also to evaluate their Vertical and East-West components with high details. The generated interferometric pattern is characterized by a double-eyed co-seismic shape that spans 20 km along the NNW-SSE direction and that well coincides with the epicentral areas. We modeled the seismic source that well fit the Mw 6.2 event. In particular, for this analysis, we separately applied an analytical Okada approach as well as a 3D Finite Element (FE) numerical modeling, the latter jointly exploiting DInSAR measurements and structural-geological data. The model obtained via the FE approach suggests that the Amatrice 2016 earthquake nucleated at 8 km deep along the intersection line between the Vettoretto-Redentore and the Northern Gorzano faults, and instantly geminated in two rupture patches that radiated with an approximate bilateral symmetry on the two fault planes. The two rupture patches covered differently shaped slip area, with aspect ratio that well recalls the shape of the interferometric lobes of ground subsidence at the two faults hanging wall. The different shapes of the two lobes are partially associated to the different dip-angle of the Vettoreto-Redentore and Gorzano faults (50° ad 60° respectively). In summary, we found evidences of bilateral rupture propagating along two en-echelon faults connected at the hypocenter.

Flank instability is common at volcanoes, even though the subsurface structures, including the depth to a detachment fault, remain poorly constrained. Here, we use a multidisciplinary approach, applicable to most volcanoes, to evaluate the detachment depth of the unstable NE flank of Mt. Etna. InSAR observations of Mount Etna during 1995-2008 show a trapdoor subsidence of the upper NE flank, with a maximum deformation against the NE Rift. The trapdoor tilt was highest in magnitude in 2002-2004, contemporaneous with the maximum rates of eastward slip along the east flank. We explain this deformation as due to a general eastward displacement of the flank, activating a rotational detachment and forming a rollover anticline, the head of which is against the NE Rift. Established 2D rollover construction models, constrained by morphological and structural data, suggest that the east-dipping detachment below the upper NE flank lies at around 4 km below the surface. This depth is consistent with seismicity that clusters above 2-3 km below sea level. Therefore, the episodically unstable NE flank lies above an east-dipping rotational detachment confined by the NE Rift and Pernicana Fault. Our approach, which combines short-term (InSAR) and long-term (geological) observations, constrains the 3D geometry and kinematics of part of the unstable flank of Etna and may be applicable and effective to understand the deeper structure of volcanoes undergoing flank instability or unrest.

Volcanoes deform as a consequence of the rise and storage of magma; once magma reaches a critical pressure, an eruption occurs. However, how the edifice deformation relates to its eruptive behavior is poorly known. Here, we produce a joint interpretation of spaceborne InSAR deformation measurements and volcanic activity at Mt. Etna ( Italy), between 1992 and 2006. We distinguish two volcano-tectonic behaviors. Between 1993 and 2000, Etna inflated with a starting deformation rate of similar to 1 cm yr(-1) that progressively reduced with time, nearly vanishing between 1998 and 2000; moreover, low-eruptive rate summit eruptions occurred, punctuated by lava fountains. Between 2001 and 2005, Etna deflated, feeding higher-eruptive rate flank eruptions, along with large displacements of the entire East-flank. These two behaviors, we suggest, result from the higher rate of magma stored between 1993 and June 2001, which triggered the emplacement of the dike responsible for the 2001 and 2002-2003 eruptions. Our results clearly show that the joint interpretation of volcano deformation and stored magma rates may be crucial in identifying impending volcanic eruptions.

We have investigated the recent deformation affecting the Messina Strait area in South Italy, across the Calabria and the Sicilia Regions. Messina Strait is an extensional tectonic feature that separates peninsular Italy from Sicily, and it is also one of the most seismically active and deforming area of the Mediterranean. It is located between the Neogene Tyrrhenian backarc basin, developed in the hanging wall of the Apennines, and the Mesozoic-Paleogene Ionian basin, which is the foreland and the area of propagation of the Neogene to present Apennines accretionary prism. We have exploited Synthetic Aperture Radar (SAR) data along the time period between 2002 and 2010 by applying the advanced Differential Interferometric Synthetic Aperture Radar (DInSAR) technique referred to as Small BAseline Subset (SBAS) algorithm. GPS data relative to permanent stations within the study area have been also used. © 2013 IEEE.

We investigate the deformation of Mt. Etna volcano (Italy) by exploiting the advanced Differential Synthetic Aperture Radar Interferometry (DInSAR) technique referred to as the Small BAseline Subset (SBAS) algorithm. In particular, we take advantage of the multi-sensor data processing capability of the SBAS algorithm which allows us to generate Mt. Etna mean deformation velocity maps and the corresponding time series in the last eighteen years. To achieve this task we exploit different set of SAR data collected by the European (ERS-1/2, ENVISAT) satellites in the 1992-2010 time interval, and by the Italian COSMO-SkyMed constellation during 2009-2010 period. We also benefit from the availability of ERS-ENVISAT multi-orbit (ascending and descending) data in order to discriminate the vertical and East-West components of the volcano edifice displacements and generate the relevant time series. Finally, we evidence how the higher spatial resolution and denser temporal sampling of the COSMO-SkyMed data, with respect to the European satellites, permit to follow with more details the complex deformative pattern which has characterized the volcano in the last two years.

We investigate the surface displacements in the area affected by the April 2009 L'Aquila earthquake (Central Italy) through an advanced DInSAR analysis. In particular, we apply the SBAS approach to retrieve deformation maps and displacement time series from ENVISAT data acquired between February 2003 and October 2009 and COSMO-SkyMed data during the six-month interval following the earthquake. Our analysis shows no evidence of pre-seismic surface deformation at the 35-day temporal sampling of the ENVISAT sensor. On the other hand, by benefiting of the high spatial resolution and temporal sampling of the COSMO-SkyMed satellites, we measure post-seismic displacements at an unprecedented level of detail for a DInSAR analysis. This allows us to identify three main areas that continue to deform after the earthquake. In addition, our modeling shows that the post-seismic displacements are very likely related to the fault afterslip, since their decay times are on the order of 10^1-10^2 days.

We investigate the deformation of Mauna Loa and Kilauea volcanoes, Hawaii, by exploiting the advanced differential Synthetic Aperture Radar Interferometry (InSAR) technique referred to as the Small BAseline Subset (SBAS) algorithm. In particular, we present time series of line-of-sight (LOS) displacements derived from SAR data acquired by the ASAR instrument, on board the ENVISAT satellite, from the ascending (track 93) and descending (track 429) orbits between 2003 and 2008. For each coherent pixel of the radar images we compute time-dependent surface displacements as well as the average LOS deformation rate. Our results quantify, in space and time, the complex deformation of Mauna Loa and Kilauea volcanoes. The derived InSAR measurements are compared to continuous GPS data to asses the quality of the SBAS-InSAR products.