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

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

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

Spatial and temporal distribution of vertical ground movements at Mt. Vesuvius in the period 1973-2009

Since the early ’70s vertical ground movements at Mount Vesuvius area have been investigated and monitored by the Osservatorio Vesuviano (Istituto Nazionale di Geofisica Vulcanologia - Osservatorio Vesuviano since 2001). This monitoring began with the installation of a high-precision leveling line in the region at medium-high elevations on the volcano. The deformation pattern and expected strain field assessment methods in the volcanic structure induced by inner sources has demanded in subsequent years the expansion of the leveling network up to cover the whole volcanic area, enclosing part of leveling lines of other institutions. As a result of this expansion, the Mt. Vesuvius Area Leveling Network (VALN) has today reached a length of about 270 km and consists of 359 benchmarks. It is configured in 21 circuits and is connected, westward, to the Campi Flegrei leveling network and, northward, to the Campania Plain leveling network. The data collected have been carefully re-analyzed for random and systematic errors and for error propagation along the leveling lines to identify the areas affected by significant ground movements. For each survey, the data were rigorously adjusted and vertical ground movements were evaluated by differentiating the heights calculated by the various measurements conducted by the Osservatorio Vesuviano from 1973 to 2009

Ground deformation analysis at Campi Flegrei (Southern Italy) by CGPS and tide-gauge network

Campi Flegrei caldera is located 15 km west of the city of Naples, within the central-southern sector of a large graben called Campanian Plain. It is an active volcanic area marked by a quasi-circular caldera depression, formed by a huge ignimbritic eruption occurred about 37000 years ago. This caldera was generated by several collapses produced by strong explosive eruptions (the last eruption, occurred in 1538, built an about 130 m spatter cone called Mt. Nuovo). Campi Flegrei area periodically experiences significant deformation episodes, with uplift phenomena up to more than 3.5 m in 15 years (from 1970 to 1984), which caused during 1983-84 the temporary evacuation of about 40000 people from the ancient part of Pozzuoli town. The deformation field obtainable by CGPS and tidegauge stations plays an important role for the modelling and interpretation of volcanic phenomena, as well as for forecasting purposes. The structural complexity of the Campi Flegrei area, together with the evidence of a strong interaction between magmatic chamber and shallow geothermal system, calls for a detailed characterization of the substructure and of magma-water interaction processes. The incoming experiment of deep drilling, down to about 4 km, will give detailed structural and physical constraints able to resolve the intrinsic ambiguities of geophysical data and in particular geodetic ones. In this poster we describe the recent ground deformations at Campi Flegrei area by means of GPS technique and tide gauge stations, discussing the possible interpretations also in light of further constraints likely coming from the next CFDDP (Campi Flegrei Deep Drilling) deep drilling experiment