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The Global Navigation Satellite System (GNSS) represents a primary data source in Solid Earth Sciences. In order to investigate the Earth’s crustal deformation, time series of the estimated daily positions of the stations are routinely analyzed at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) to investigate the deformation of the Earth’s surface caused by tectonic and non­tectonic processes. The GNSS observations of the stations are processed using the three main scientific software: GAMIT/GLOBK, BERNESE, and GIPSY OASIS II. The accuracy and the strength of geodetic solutions often depend on the geometry and spatial density of the network, and the availability and quality of GNSS data. In many circumstances, GNSS networks are deployed for topographic purposes by private or public institutions, and a significant number of GNSS stations in large regions acquire continuous observations. It may happen that such networks do not collect and distribute data according to IGS standards, so it could be difficult to analyze this data using automated data­processing tools. For that reason, this data is often ignored or partially used by the scientific community, despite their potential usefulness in geodynamic studies. We have attempted troubleshooting this problem by establishing a centralized storage facility in order to collect all available GNSS data and standardize both formats and metadata information. Here we describe the processes and functions that manage this unified repository, called MGA (Mediterranean GNSS Archive), which regularly collects GNSS RINEX files from a large number of CORS (Continuously Operating Reference Station) located across a wide region of mainly the European and African plates. RINEX observation data and metadata information are provided to the analysts through an FTP server and dedicated web­services. The complete data set is stored in a PostgreSQL database in order to easily retrieve pieces of information and efficiently manage the archive content. The system implements many high­level services that include scripts to download files from remote archives and to detect new available data, web applications such as API (Application Program Interface) to interact with the system, and background services that interact with the database. During the development of this product, particular attention was paid to what has already been achieved by the EPOS Thematic Core Service WP10 (https://www.epos­eu.org/tcs/gnss­data­ and­products), whose objective was: “... to develop an open source platform with programmatic and web interfaces to store and disseminate raw data and metadata from GNSS stations operating in Europe”. Many ideas and tools presented here were inspired by that project.

Massive analysis of GNSS data (Global Navigation Satellite System) requires the development of specific tools to automate the different steps of processing: from data download to ground displacements estimates. In this technical report we describe the tools and algorithms we have developed to handle the metadata associated with GNSS observations from continuous networks operating in the EuroMediterranean and African area, which are routinely processed by the three main INGV data analysis centers. Obtaining accurate metadata, which records information on how a GNSS station is equipped (receiver, antenna, monument, etc..), is mandatory in order to obtain accurate GNSS stations daily position and their evolution through time. Here we will describe the processing chain, the software developed using opensource programming language, describing the major issues found in treating incomplete, inconsistent or wrong information, and the methods adopted to minimize or resolve these problems. The software developed is going to be implemented in the centralized GNSS data and metadata archive that we are realizing at INGV, and that will serve both institutional activities and research projects. The goal of this tool is to minimize errors and reduce/avoid the human intervention in handling a large set of information, facilitating the automatic analysis of data from thousands of GNSS stations on a daily basis. The software acronym is pyGLogDB, which stands for: “python GNSS Logfile elaboration with the support of DataBase”.

Nell’ambito del progetto “S.O.I.R. monitoraggio futuro”, la sezione INGV dell’Osservatorio Nazionale Terremoti (ONT), ha rivolto l’attenzione principalmente nel centro Italia e nelle aree non vulcaniche della Sicilia. La scelta di convogliare le attività di potenziamento in queste due aree è stata attentamente ponderata: da un lato la necessità di ottimizzare e irrobustire la rete di monitoraggio in centro Italia, un’area ad elevatissimo rischio interessata negli ultimi anni da importanti sequenze sismiche, dall’altro quello di avviare lo sviluppo della rete multiparametrica in Sicilia, un territorio che offre una innumerevole varietà di ambienti e sotto-sistemi, che rendono tale regione un laboratorio naturale unico al mondo. Gli interventi ONT possono essere essenzialmente raggruppati in due categorie: quelli finalizzati all’aumento del grado di multiparametricità del sito e quelli mirati all’aumento del livello di affidabilità e robustezza del servizio. La presenza simultanea di molteplici sensori permette infatti di migliorare la comprensione del fenomeno sismico e dei fenomeni ad esso associati, di aprire nuove prospettive per la valutazione della pericolosità sismica, per la previsione probabilistica dei terremoti, per la prevenzione e l’aumento di resilienza, e più in generale per la mitigazione del rischio sismico. Mentre sistemi di back-up dell’alimentazione e la ridondanza di trasmissione, garantiscono una maggiore continuità soprattutto per le stazioni considerate strategiche per il servizio di monitoraggio e di sorveglianza sismica.

All’interno del WP3 del progetto “S.O.I.R. monitoraggio futuro”, il gruppo GNSS dell’ONT aveva l’obiettivo di implementare procedure per l’aggiornamento automatico, con minima latenza (legata ai prodotti IGS o JPL necessari all’analisi), delle serie temporali di spostamento della rete RING e di calcolare spostamenti cosismici in tempi rapidi, in caso di evento sismico significativo, anche utilizzando dati messi a disposizione da altre reti. Per raggiungere questi obiettivi era necessario rendere disponibili ai centri di analisi dati GNSS i file giornalieri in formato RINEX e i relativi metadati associati, aggiornati giornalmente. Per ogni stazione GNSS di interesse, i metadati associati a tali dati consistono principalmente in informazioni legate alla storia della strumentazione installata e ai valori dell’altezza dell’antenna GNSS rispetto al caposaldo geodetico. Per quanto riguarda i dati e i metadati della RING , essi sono già oggetto di un controllo quotidiano nell’ambito delle attività ordinarie legate alla manutenzione e gestione dell’intera infrastruttura RING e sono disponibili attraverso il data repository. Per quanto riguarda le altre reti permanenti, invece, la disponibilità dei metadati non è garantita. Per reti sviluppate per scopi diversi da quelli scientifici (topografici, commerciali, ecc.), infatti, queste informazioni o non ci sono o non sono costantemente monitorati o aggiornati o sono incompleti. La disponibilità di dati e metadati delle reti GNSS esistenti permetterebbe ai centri di analisi INGV di implementare procedure automatizzate per analizzare i dati giornalmente, e caricare i risultati in termini di serie temporali, in un formato comune, su un archivio condiviso in rete. Per raggiungere questo scopo, in questo articolo descriveremo le attività svolte per: 1) la realizzazione di un archivio dei dati e metadati delle stazioni GNSS permanenti in area Euro-Mediterranea; 2) l’implementazione di procedure automatiche per la generazione di prodotti GNSS (finali e rapidi) con software non commerciali diversi (Bernese, Gipsy, Gamit); 3) la visualizzazione dei prodotti geodetici (es. serie temporali di spostamento) ottenuti dall’analisi su menzionata.

Two alluvial plain sinkhole clusters in the lowermost part of the Modena Province (Italy) are illustrated. They could probably be classified as suffusion sinkholes, according the latest Italian taxonomy suggestions. Both clusters developed in orchards, i.e. in areas undisturbed by yearly ploughing. They are characterized by similar surface evidence and ground deformations, and were surveyed by geophysical, hydrochemical, GPS and traditional topographic techniques. In the first case, the cluster is located over the subsiding limb of a vertical deformation possibly coinciding with a minor (tectonic) disturbance. In the second example, the available data do not allow us to verify the existence of a buried disturbance, but strongly suggest this possibility. Direct relationships do not appear to exist between the phreatic water-table level and nearest river flood water levels. In both cases, the phreatic aquifer consists of slightly brackish waters. In the second case, a relationship between the water chemical concentration and tectonic stresses appears to be recorded. Thus, if the two clusters prove suffusion phenomena, these must be regarded as directed vertically downwards.

A series of studies concerning the surficial aquifers of Emilia alluvial plain showed the existence of hydrochemical anomalies suggesting a widespread vertical circulation of the various fluid phases hosted in the thick Pleisto-Olocene succession. The occurrence of liquid and gaseous fluid vents is easily detectable by means of their brackish character (with an electric conductivity, Ec, up to 18,000/22,000 µS/cm, at 25° C) and it is related to various fractures systems difficult to study in detail. According to detailed stratigraphical and structural data (AGIP’s seismic sections and industrial wells) the main source of the salt vertical uprisings is the Middle Pleistocene marine Clinoforms Lithosome (Subsyntheme Marine Quaternary 3), showing a wide distribution in the Po Plain-Adriatic basin. The occurrence of very low Ec freshwaters (250 µS/cm) sometimes accompanied by thermal anomalies (up to 7°C lower than the average annual temperature) is an interesting problem hard to solve. The hydrochemical and thermal anomalies recorded in the underground waters were often very fast and penecontemporaneous over 30-40 km distances. These anomalies are genetically related to the earthquakes of the inner Po Plain Zone and adjacent North-Apennine chain. The active tectonic control played by the frontal zone of the North-Apennine Chain is fundamental for the explanation of the recorded anomalies. Ground collapse and disarrangements recorded and monitored over time are related to the loss in volume, underneath the surface due to the sediments compaction processes and to other causes; also reminiscent effects of the deep gas-hydrates liquefaction, occurred in the far past, cannot be excluded. Paroxysmal (explosive) fluid (methane) episodes and embankment underseepage (suffosion) are not consistent with the recorded data.

Primo esempio di applicazione di survey geofisico (GPR) ad alta risoluzione per lo studio delle vie di ablazione del sedimento dagli amiti superficiali, meccanismo che porta alla repentina comparso di scavernamenti suprficiali nelle aree di pianura dell'Emilia Romagna ormai da una decina di anni. Il metodo ha permesso indirettamente di ipotizzare vie pervie a sviluppo principalmente verticale (oppure orizzontale ma con dimensioni non detettabili dal metodo). Due interessanti portati laterali della ricerca: 1) individuazione di bande verticali di anomalia di ampiezza pl,urimetrica che potrebbero costituire lesioni in nuce della coltre sedimentaria e configiurarsi come vie preferenziali di risali6ta dei convogli salmastri; 2)possibilità di interpretazione in chiave stratigrafica di estremo dettaglio dei radargrammi oltre la soglia di rumore del metodo.

In Antarctica, the severe climatic conditions and the thick ice sheet that covers the largest and most internal part of the continent make it particularly difficult to systematically carry out geophysical and geodetic observations on a continental scale. It prevents the comprehensive understanding of both the onshore and offshore geology as well as the relationship between the inner part of East Antarctica (EA) and the coastal sector of Victoria Land (VL). With the aim to reduce this gap, in this paper multiple geophysical dataset collected since the 1980s in Antarctica by Programma Nazionale di Ricerche in Antartide (PNRA) were integrated with geodetic observations. In particu-lar, the analyzed data includes: (i) Geodetic time series from Trans Antarctic Mountains DEFormation (TAMDEF), and Victoria Land Network for DEFormation control (VLNDEF) GNSS stations installed in Victoria Land; (ii) the integration of on-shore (ground points data and airborne) gravity measurements in Victoria Land and marine gravity surveys performed in the Ross Sea and the nar-row strip of Southern Ocean facing the coasts of northern Victoria Land. Gravity data modelling has improved the knowledge of the Moho depth of VL and surrounding the offshore areas. By the integration of geodetic and gravitational (or gravity) potential results it was possible to better con-strain/identify four geodynamic blocks characterized by homogeneous geophysical signature: the Southern Ocean to the N, the Ross Sea to the E, the Wilkes Basin to the W, and VL in between. The last block is characterized by a small but significant clockwise rotation relative to East Antarctica. The presence of a N-S to NNW-SSE 1-km step in the Moho in correspondence of the Rennick Geo-dynamic Belt confirms the existence of this crustal scale discontinuity, possibly representing the tectonic boundary between East Antarctica and the northern part of VL block, as previously pro-posed by some geological studies.

In order to make inferences on the geodynamics of Antarctica, geodetic and gravimetric maps derived from past and new observations can be used. This paper provides new insights into the geodynamics of Antarctica by integrating data at regional and continental scales. In particular, signatures of geodynamic activity at a regional extent have been investigated in Victoria Land (VL, Antarctica) by means of Global Navigation Satellite System (GNSS) permanent station observations, data from the VLNDEF (Victoria Land Network for Deformation control) discontinuous network, and gravity station measurements. At the continental scale, episodic GNSS observations on VLNDEF sites collected for 20 years, together with continuous data from the International GNSS Service (IGS) and Polar Earth Observing Network (POLENET) sites, were processed, and the Euler pole position assessed with the angular velocity of the Antarctic plate. Both the Bouguer and the free-air gravity anomaly maps were obtained by integrating the available open-access geophysics dataset, and a compilation of 180 gravity measurements collected in the VL within the Italian National Program for Antarctic Research (PNRA) activities. As a result, new evidence has been detected at regional and continental scale. The main absolute motion of VL is towards SE (Ve 9.9 &plusmn, 0.26 mm/yr, Vn &minus, 11.9 &plusmn, 0.27 mm/yr) with a pattern similar to the transforms of the Tasman and Balleny fracture zones produced as consequence of Southern Ocean spreading. Residual velocities of the GNSS stations located in VL confirm the active role of the two main tectonic lineaments of the region, the Rennick&ndash, Aviator and the Lillie&ndash, Tucker faults with right-lateral sense of shear. The resulting VL gravity anomalies show a NW region characterized by small sized Bouguer anomaly with high uplift rates associated and a SE region with low values of Bouguer anomaly and general subsidence phenomena. The East and West Antarctica are characterized by a different thickness of the Earth&rsquo, s crust, and the relative velocities obtained by the observed GNSS data confirm that movements between the two regions are negligible. In East Antarctica, the roots of the main subglacial highlands, Gamburtsev Mts and Dronning Maud Land, are present. The Northern Victoria Land (NVL) is characterized by more scattered anomalies. These confirm the differences between the Glacial Isostatic Adjustment (GIA) modeled and observed uplift rates that could be related to deep-seated, regional scale structures.