Isola di Vulcano (Isole Eolie) movimenti verticali del suolo: livellazione di precisione ottobre 2003

The levelling network installed and managed by the Osservatorio Vesuviano for monitoringvertical ground movements on Volcano island is currently made up of 100 benchmarks(bm) and extends about 24 km as a whole. The reference benchmark for calculating height variations is benchmark 1A located at Volcano Piano, which is a relatively stable area as compared with the northern part of the island. The presently operating network has been enlarged and thickened several times since June 1976, when the first levelling line was installed and surveyed. Twentyseven surveys has been conducted between June 1976 and October 2003. Actually, the configuration of the network presents a greater density of benchmarks in the center-northern sector of the island. The measurement tecnique used is precise levelling. The surveys are performed with autolevelling instruments (Wild NA2) equipped with optical micrometers and invar rods. The last levelling survey has been carried out in the first two weeks of October 2003. The comparison of September 1999 (previous levelling) with October 2003 data indicates a significant subsidence of the center-northern area of the island

On the mechanics of caldera resurgence of Ischia Island (southern Italy)

A model of caldera resurgence was applied to the Island of Ischia to explain uplift, volcanic activity and tectonics on Mount Epomeo, as well as historical seismicity and slow ground movements recorded for the past 2000 years. A two-dimensional mechanical model was utilized for the crust, which was considered to be an elastic plate overlying a laccolith. Geometric dimensions and mechanical parameters were constrained using geological, geophysical and geochemical data. We propose that a laccolith, with a diameter L of c. 10 km, and a depth of up to 1 km in the centre of the island, triggered the caldera resurgence after the Mount Epomeo Green Tuff eruption forming the caldera (55 000 a BP). A bending phase and a punched laccolith phase are thought to have caused the observed deformations in the caldera. These processes control the tectonics at the boundary of the Mount Epomeo resurgent structure, volcanic activity and dynamics of the island

Resurgence and flank failure of Mt. Epomeo, Ischia Island (Southern Italy)

Risorgenza e collasso laterale del Monte Epomeo, Isola d’Ischia Il Monte Epomeo (787 m a.s.l.), ubicato nel settore centrale dell’isola d’Ischia, mostra lo smantellamento del settore meridionale, depositi di debris e franamenti diffusi che testimoniano la natura instabile del monte. A seguito dell’eruzione ignimbritica del Tufo Verde dell’Epomeo (55.000 anni), che genera una struttura calderica (10x7 km2), inizia la risorgenza della caldera fino alla formazione del Monte Epomeo. Il sollevamento, generato dall’intrusione di un laccolite fino a circa 1 km di profondità, avrebbe determinato una forte instabilità gravitativa del blocco risorgente e prodotto uno o più collassi laterali. Questi hanno lasciato una struttura a ferro di cavallo, tipica di processi da “avalancing”, aperta verso sud, e depositi con topografia “hummocky” estesi a sud dell’Epomeo e rilevati recentemente da esplorazioni sul fondo marino. Il processo che ha generato il collasso e la formazione di un avalanche caldera è stato esaminato attraverso l’analisi della dinamica e dei caratteri geologici, geomorfologici e strutturali dell’area. Attualmente l’isola è caratterizzata da una fase di stasi della risorgenza testimoniata da una condizione di moderata stabilità dei versanti dell’Epomeo. Quanto osservato indicherebbe una bassa dinamica endogena nell’isola

GPS time series at Campi Flegrei caldera (2000-2013)

The Campi Flegrei caldera is an active volcanic system associated to a high volcanic risk, and represents a well known and peculiar example of ground deformations (bradyseism), characterized by intense uplift periods, followed by subsidence phases with some episodic superimposed mini-uplifts. Ground deformation is an important volcanic precursor, and, its continuous monitoring, is one of the main tool for short time forecast of eruptive activity. This paper provides an overview of the continuous GPS monitoring of the Campi Flegrei caldera from January 2000 to July 2013, including network operations, data recording and processing, and data products. In this period the GPS time series allowed continuous and accurate tracking of ground deformation of the area. Seven main uplift episodes were detected, and during each uplift period, the recurrent horizontal displacement pattern, radial from the “caldera center”, suggests no significant change in deformation source geometry and location occurs. The complete archive of GPS time series at Campi Flegrei area is reported in the Supplementary materials. These data can be usefull for the scientific community in improving the research on Campi Flegrei caldera dynamic and hazard assessment

Ground deformation modeling of flank dynamics prior to the 2002 eruption of Mt. Etna

On 22 September 2002, 1 month before the beginning of the flank eruption on the NE Rift, an M-3.7 earthquake struck the northeastern part of Mt. Etna, on the westernmost part of the Pernicana fault. In order to investigate the ground deformation pattern associated with this event, a multi-disciplinary approach is presented here. Just after the earthquake, specific GPS surveys were carried out on two small sub-networks, aimed at monitoring the eastern part of the Pernicana fault, and some baselines belonging to the northeastern EDM monitoring network of Mt. Etna were measured. The leveling route on the northeastern flank of the volcano was also surveyed. Furthermore, an investigation using SAR interferometry was performed and also the continuous tilt data recorded at a high precision sensor close to the epicenter were analyzed to constrain the coseismic deformation. The results of the geodetic surveys show a ground deformation pattern that affects the entire northeastern flank of the volcano, clearly shaped by the Pernicana fault, but too strong and wide to be related only to an M-3.7 earthquake. Leveling and DInSAR data highlight a local strong subsidence, up to 7 cm, close to the Pernicana fault. Significant displacements, up to 2 cm, were also detected on the upper part of the NE Rift and in the summit craters area, while the displacements decrease at lower altitude, suggesting that the dislocation did not continue further eastward. Three-dimensional GPS data inversions have been attempted in order to model the ground deformation source and its relationship with the volcano plumbing system. The model has also been constrained by vertical displacements measured by the leveling survey and by the deformation map obtained by SAR interferometry

Sea level changes, ground deformations, human settlements in the bay of Naples

Ground deformations in active volcanoes are considered precursors of eruptions according to the most tested models; therefore monitoring networks of ground deformations are installed on inhabited dangerous volcanoes. Direct measurements of such deformations are carried out since 1861 when Luigi Palmieri monitored the eruption at Mt. Vesuvius with levelings along the shoreline near the town of Torre del Greco. Relative sea level changes were measured at Serapeo in Pozzuoli in the middle of 19th century to record soil uplifts which are locally known as bradyseism. To enlarge the time series of data on these phenomena it is necessary to utilize historical and prehistorical informations on the location of shore-line of human settlements. As regards the regions of active volcanoes as the Neapolitan one three processes contribute to sea level changes as eustatism, regional tectonics and local intrusive and effusive phenomena. Therefore at the same time the relative sea level should be different at far-away places only few kilometres according to the volcanic activity. In fact eustatic and tectonic processes contribute to sea level changes with very lesser rates than volcanic activity. The Neapolitan region for its geological history is an excellent laboratory for testing the validation of new paradigms for some natural phenomena

Terremoto del 29 dicembre 2013 nel Matese (MW = 5.0). Indagine speditiva degli effetti nell’area epicentrale e analisi preliminare della sequenza sismica.

Il 29 dicembre 2013 un terremoto di magnitudo Mw=5.0 (profondità 10.5 km) è avvenuto nell'area dei Monti del Matese alle ore 18:08:43 ora locale

First evidence of post-seismic deformation in the central Mediterranean: Crustal viscoelastic relaxation in the area of the 1980 Irpinia earthquake (Southern Italy)

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Characterization of GPS time series at the Neapolitan volcanic area by statistical analysis

The GPS time series recorded at the Neapolitan volcanic area reveals a very peculiar behavior. When a clear deformation is observed, the amplitude distribution evolves from a super‐Gaussian to a broader distribution. This behavior can be characterized by evaluating the kurtosis. Spurious periodic components were evidenced by independent component analysis and then removed by filtering the original signal. The time series for all stations was modeled with a fifth‐order polynomial fit, which represents the deformation history at that place. Indeed, when this polynomial is subtracted from the time series, the distributions again become super‐Gaussian. A simulation of the deformation time evolution was performed by superposing a Laplacian noise and a synthetic deformation history. The kurtosis of the obtained signals decreases as the superposition increases, enlightening the insurgence of the deformation. The presented approach represents a contribution aimed at adding further information to the studies about the deformation at the Neapolitan volcanic area by revealing geologically relevant data

S.A.G.NET: Rete GPS dell'Appennino meridionale.

The Matese carbonatic massive occupies the northernmost part of the campanian Apennine while Sannio mounts, located to the East of massive, consists primarily of quaternary deposits and represent the area of Apennine chain degrading to East towards the Bradanica foredeep. The area was affected in historical time by several destructive earthquakes. The first ground deformation studies in this area started from 1990-2000 with the definition of geodetic networks, covering all or part of the massive Matese, with the aim of evaluating seismogenic sources responsible for the seismicity of the area. In 2002, a careful inspection of the existing GPS benchmarks was carried out; those which had a good state of preservation and a good level of reliability were included into a new geodetic Matese network, consisting of 38 3D benchmarks. Several surveys were conducted in 2000, 2002 and 2004,with the aim of defining the strain field, defined by plano-altimetric components. In 2005, an intensive work of gathering and validating available data started, integrating data collected by previous surveys with those collected during the new survey carried out in 2006. This work describes in detail the various stages of implementing the final network S.A.G.NET, whose geometry was also bound to the distribution of the known seismogenic sources present in the area. We also show the first results obtained from data collected from2000 to 2006 and the resulting kinematic model for this area