Kinematic model of active extension across the Umbria-Marche Apennines from GPS measurements: fault slip-rates and interseismic coupling of the Alto Tiberina low-angle normal fault

The Umbria-Marche Apennines are characterized mainly by SW-NE oriented extensional deformation and most of major historical and instrumental earthquakes occurred mainly on the western side of chain, bounded by west-dipping buried high-angle normal faults. Recent studies about the northernmost part of Umbria-Marche region show seismic and tectonic activity on correspondence of the east-dipping Alto Tiberina (AT) low-angle normal fault (LANF), which is widely documented by geological data and deep seismic reflection profiles. In this area which of the known fault systems play a major role in accommodating the extension, and which are the modes (seismic VS aseismic deformation) this extension is taken up, is still a debated topic. During last years on Umbria-Marche Apennines close to Gubbio fault (GuF) a dense network of continuous GPS stations, belonging to the RING-INGV network, has been installed, improving significantly the spatial resolution of the detectable geodetic gradients. We used a self-consistent kinematic block modeling to study this sector of the Umbria-Marche Apennines, in order to understand which fault system is accommodating the tectonic extension. We found that both fault systems, i.e. the Alto Tiberina LANF and the antithetic high-angle normal faults, are needed to better reproduce the nearfield GPS velocities, obtaining kinematic agreement with geological slip-rates. Moreover we parameterized the ATF fault as a, more realistic, curved surface to infer the distribution of interseismic coupling (IC), which is validated by numerous resolution tests. The obtained IC distribution shows a correlation between relocated microseismicity and uncoupled patches attributed to aseismic creeping behavior, which could be explained by the presence of fluid overpressure. Otherwise this correlation has been verified with a very small quantity of events (almost 400) and it might be of interest to evaluate this correlation with future available data

Kinematic block modeling of GPS velocities in Italy and seismic potential

We use a dense GPS velocity field, from the analysis of >1000 continuous stations, and elastic block modeling to study the interseismic strain accumulation along the Alpine and Apennines active tectonic belts in Italy. We consider available fault catalogues, instrumental and historical seismicity to determine the blocks boundaries geometry, parameterized as uniformly slipping rectangular planes. We invert horizontal velocities to estimate Euler vectors of tectonic blocks together with slip-rates at block-bounding faults. When allowed by density of GPS data, we optimize faults dip and locking-depth by searching the parameters that provide the best fit to local GPS data. Overall we obtain a good fit of the horizontal velocities and geodetic slip rates that are kinematically consistent with available geological and seismotectonic information. We use the best-fit geometric and kinematic model parameters to compute the expected GPS velocities over a dense regular grid. Denser model velocities are used to estimate the velocity gradient field on a regular grid, made by cell elements of 0.25°x0.25°. Geodetic strain-rates at each cell are converted into seismic moment accumulation rates, following the Kostrov formulation, considering as seismogenic thickness values obtained from a crustal (EPcrust) model and earthquake hypocentral distribution. Geodetic moment accumulation rates are compared with seismic moment rates released by earthquakes, obtained from the analysis of a seismic catalogue realized by merging several instrumental and historical catalogues covering the 1600-2012 timespan, and uniformly defined moment magnitudes. The comparison between geodetic moment accumulation rates and seismic moment release rates highlights regions with significant moment deficits but also areas with a surplus of the seismic moment released, with important implications for seismic hazard evaluations and assumptions behind the approach used in this work

Fault Geometry, Coseismic Slip Distribution and Coulomb Stress Change Associated to the 6 April 2009, Mw 6.3, L’Aquila Earthquake Imaged From Inversion of GPS Displacements

After the April, 6 2009 Mw=6.3 L’Aquila earthquake, the coseimic deformation has measured by > 70 Global Positioning System (GPS) stations. We use a rectangular uniform-slip dislocation and a constrained, non-linear optimization algorithm, obtaining a rupture occurred on a N129°E striking and 50° SW-ward dipping normal fault. Our distributed slip model exhibits the highest slip of the order of ∼1 m. We do also bootstrap and resolution analysis to quantify goodness of our model. We analyze the Coulomb stress change affected by the major aftershocks, and compare the results obtained from the uniform slip and the heterogeneous slip models

Refining Rates of Active Crustal Deformation in the Upper Plate of Subduction Zones, Implied by Geological and Geodetic Data: The E-Dipping West Crati Fault, Southern Italy

We investigate crustal deformation within the upper plate of the Ionian Subduction Zone (ISZ) at different time scales by (i) refining geodetic rates of crustal extension from continuous Global Navigation Satellite System (GNSS) measurements and (ii) mapping sequence of Late Quaternary raised marine terraces tectonically deformed by the West Crati normal fault, in northern Calabria. This region experienced damaging earthquakes in 1184 (M 6.75) and 1854 (M 6.3), possibly on the E-dipping West Crati fault (WCF) which, however, is not unanimously considered to be a seismogenic source. We report geodetic measurements of extension and strain rates across the strike of the E dipping WCF and throughout the northern Calabria obtained by using velocities from 18 permanent GNSS stations with a series length longer than 4.5 years. These results suggest that crustal extension may be seismically accommodated in this region by a few normal faults. Furthermore, by applying a synchronous correlation approach, we refine the chronology of understudied tectonically deformed palaeoshorelines mapped on the footwall and along the strike of the WCF, facilitating calculation of the associated fault-controlled uplift rates. Raised Late Quaternary palaeoshorelines are preserved on the footwall of the WCF indicating that “regional” uplift, likely related to the deformation associated either with the subduction or mantle upwelling processes, is affected by local footwall uplift. We show that GIS-based elevations of Late Quaternary palaeoshorelines, as well as temporally constant uplift rates, vary along the strike of the WCF, implying normal faulting activity through time. This suggests that (i) the fault slip rate governing seismic hazard has also been constant over the Late Quaternary, over multiple earthquake cycles, and (ii) our geodetically derived fault throw rate for the WCF is likely a more than reasonable value to be used over longer time scales for an improved seismic hazard assessment. Overall, we emphasize the importance of mapping crustal deformation within the upper plate above subduction zones to avoid unreliable interpretations relating to the mechanism controlling regional uplift

Data analysis of Permanent GPS networks in Italy and surrounding region: application of a distributed processing approach

We describe the procedures used to combine into a uniform velocity solution the observations of more than 80 continuous GPS stations operating in the central Mediterranean in the 1998-2004 time interval. We used a dis- tributed processing approach, which makes efficient use of computer resources, while producing velocity esti- mates for all stations in one common reference frame, allowing for an effective merging of all observations in- to a self-consistent network solution. We describe the CGPS data archiving and processing procedures, and pro- vide the main results in terms of position time-series and velocities for all stations observed for more than three years. We computed horizontal and vertical velocities accounting for the seasonal (annual and semi-annual) sig- nals, and considering the off-sets in the coordinate time-series caused by station equipment changes. Weighted post-fit RMS of the north, east and vertical velocity components are in the range of 1.57-2.08 mm, 1.31-3.28 mm, and 3.60-7.24 mm, respectively, which are reduced by solving for seasonal signals in the velocity estimates. The annual and semi-annual signals in the height components, with amplitudes up to 4.8 mm, are much stronger than those in the horizontal components. The mean amplitudes of annual and semi-annual signals are within 0.18-0.47 mm, 0.23-0.52 mm and 0.55-1.92 mm in the north, east and vertical components, respectively

Multi-technique geodetic detection of onshore and offshore subsidence along the Upper Adriatic Sea coasts

We assess about 20 years of onshore and offshore subsidence along a sector of the Upper Adriatic Sea (Italy) coastal areas affected by natural soil compaction and intense anthropogenic activities such as aquifers exploi-tation and hydrocarbons extraction. Our approach is based on the synergistic use of independent remote sensing and in-situ geodetic data to detect and spatially characterise the deformation pattern by cross-validating the different available measurements. We collect extensive datasets from i) SAR images provided by Envisat, Cosmo-SkyMed and Sentinel-1 missions, ii) GNSS measurements from continuous stations managed by public in-stitutions, local authorities and private companies and iii) Leveling surveys. The cross-validation analysis shows good agreement among all the independent datasets, thus providing a reliable assessment of the ongoing deformation. We detect an onshore and offshore subsidence peak of about -1/-1.5 cm/yr in the proximity of the coastline, close to Lido di Dante and Fiumi Uniti villages, and at the present offshore platform. The outcomes highlight how the integration of different remote sensing and in situ geodetic techniques is successful to retrieve deformation history in time and space in complex areas, where different natural and anthropogenic sources concur to the overall deformation pattern. Moreover, such approach provides a robust support to modelling studies for hazard assessment in both inland and shoreline areas

Aseismic deformation associated with an earthquake swarm in the northern Apennines (Italy)

Analyzing the displacement time series from continuous GPS (cGPS) with an Independent Component Analysis, we detect a transient deformation signal that correlates both in space and time with a seismic swarm activity (maximum Mw=3.69 \ub1 0.09) occurred in the hanging wall of the Altotiberina normal fault (Northern Apennines, Italy) in 2013\u20132014. The geodetic transient lasted 3c6 months and produced a NW-SE trending extension of 3c5.3 mm, consistent with the regional tectonic regime. The seismicity and the geodetic signal are consistent with slip on two splay faults in the Altotiberina fault (ATF) hanging wall. Comparing the seismic moment associated with the geodetic transient and the seismic events, we observe that seismicity accounts for only a fraction of the measured geodetic deformation. The combined seismic and aseismic slip decreased the Coulomb stress on the locked shallow portion of the ATF, while the transition region to the creeping section has been loaded

AlpArray-Italy: Site description and noise characterization

Within the framework of the European collaborative research initiative AlpArray (http://www.alparray.ethz. ch), the Istituto Nazionale di Geofisica e Vulcanolgia (INGV) deployed overall 20 broad-band seismic stations in Northern Italy and on two islands in the Tyrrhenian Sea (Capraia and Montecristo) during Fall-Winter 2015. The temporary deployment (16 stations) will run for two to three years and 4 INGV National Seismic Network accelerometric sites are now equipped with additional per- manent broad-band sensors. The 16 temporary stations are equipped with REF TEK 130 digitizers and Nanometrics Trillium Compact 120 s sensors, a couple have Nanometrics Trillium 120P sensors and one a Streckeisen STS2. For each site we describe the settings and discuss the noise levels, the site effects and the preliminary sensitivity analysis.Published39-528T. Sismologia in tempo realeJCR Journa

Coupled surface to deep Earth processes: Perspectives from TOPO-EUROPE with an emphasis on climate- and energy-related societal challenges

Understanding the interactions between surface and deep Earth processes is important for research in many diverse scientific areas including climate, environment, energy, georesources and biosphere. The TOPO-EUROPE initiative of the International Lithosphere Program serves as a pan-European platform for integrated surface and deep Earth sciences, synergizing observational studies of the Earth structure and fluxes on all spatial and temporal scales with modelling of Earth processes. This review provides a survey of scientific developments in our quantitative understanding of coupled surface-deep Earth processes achieved through TOPO-EUROPE. The most notable innovations include (1) a process-based understanding of the connection of upper mantle dynamics and absolute plate motion frames; (2) integrated models for sediment source-to-sink dynamics, demonstrating the importance of mass transfer from mountains to basins and from basin to basin; (3) demonstration of the key role of polyphase evolution of sedimentary basins, the impact of pre-rift and pre-orogenic structures, and the evolution of subsequent lithosphere and landscape dynamics; (4) improved conceptual understanding of the temporal evolution from back-arc extension to tectonic inversion and onset of subduction; (5) models to explain the integrated strength of Europe's lithosphere; (6) concepts governing the interplay between thermal upper mantle processes and stress-induced intraplate deformation; (7) constraints on the record of vertical motions from high-resolution data sets obtained from geo-thermochronology for Europe's topographic evolution; (8) recognition and quantifications of the forcing by erosional and/or glacial-interglacial surface mass transfer on the regional magmatism, with major implications for our understanding of the carbon cycle on geological timescales and the emerging field of biogeodynamics; and (9) the transfer of insights obtained on the coupling of deep Earth and surface processes to the domain of geothermal energy exploration. Concerning the future research agenda of TOPO-EUROPE, we also discuss the rich potential for further advances, multidisciplinary research and community building across many scientific frontiers, including research on the biosphere, climate and energy. These will focus on obtaining a better insight into the initiation and evolution of subduction systems, the role of mantle plumes in continental rifting and (super)continent break-up, and the deformation and tectonic reactivation of cratons; the interaction between geodynamic, surface and climate processes, such as interactions between glaciation, sea level change and deep Earth processes; the sensitivity, tipping points, and spatio-temporal evolution of the interactions between climate and tectonics as well as the role of rock melting and outgassing in affecting such interactions; the emerging field of biogeodynamics, that is the impact of coupled deep Earth – surface processes on the evolution of life on Earth; and tightening the connection between societal challenges regarding renewable georesources, climate change, natural geohazards, and novel process-understanding of the Earth system

Vertical displacement time series from GNSS stations in the Po river basin area

ASCII files reporting the daily GNSS vertical ground displacement time series, in the Eurasia-fixed reference frame, from January 2010 to September 2022 of continuous stations located in the Po river basin. The time series are obtained by analyzing the raw GPS observations using the GAMIT/GLOBK (version 10.71) software, following the standard procedures of the repro2 IGS reprocessing scheme (http://acc.igs.org/reprocess2.html). This is part of a large processing effort, including>4000 stations in the Euro- Mediterranean and African regions (Serpelloni et al., 2022), where sub-networks, made up of <50 stations dynamically and optimally selected based on daily data availability, are processed independently with GAMIT and later tied together using common sub-net tie sites and IGb14 core stations using the GLOBK software. This time series are used to study the effect of the drought occurring since 2021 in Northern Italy. The columns of the files are: Time, U, Su, site, long, lati, representing, respectively, epoch (in decimal years), displacement in the Up component (in mm), uncertainty (one standard deviation) of the Up component (in mm), Station ID, Longitude of the station (°), Latitude of the station (°)