A. Bonforte

We propose a preliminary complex networks based approach in order to model and characterize volcanoes activity correlation observed on a planetary scale over the last two thousand years. Worldwide volcanic activity is in fact related to the general plate tectonics that locally drives the faults activity, that in turn controls the magma upraise beneath the volcanoes. To find correlations among

We carried out a study of the seismicity and ground deformation occurred on Mount Etna volcano after the end of 2002-2003 eruption and before the onset of 2004-2005 eruption, and recorded by the permanent local seismic network run by Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania and by the geodetic surveys carried out in July 2003 and

ABSTRACT The 2007 eruption in the Sciara del Fuoco at Stromboli volcano, totally destroyed the topographic monitoring device that was installed along this steep slope to monitor the flank movement after the 2002-2003 crisis. Furthermore, the lava emitted during this last eruption formed a big fan at the NE base of the Sciara del Fuoco, due to the rapid cooling of the lava when entering the sea. To monitor the stability of this lava body emplaced over a very steep slope, 5 new benchmarks were installed in April 2007, crossing the fan approximately along the old coastline. The position of these benchmarks was measured from the robotized Total Station every 20 minutes. Later on, in June 2007, 4 further benchmarks were installed on the lava fan, 2 at higher and 2 at lower altitude with respect the former profile. In addition, a further improvement in the monitoring device was performed by installing a new reference station and optimizing the measurement cycles and strategies. Currently, the 9 benchmarks on the lava fan are surveyed every 10 minutes and clear motion toward the sea, slowly decreasing in time since the first measurements. The motion also decreases from the south-western to the north-easternern part of the fan, where it is buttressed by the northern wall of the Sciara del Fuoco. An Early warning system, based on a robust statistical method (based on the ALICE -Absolutely Local Index of Change of the Environment -index) combined with a fuzzy processing has been developed.

ABSTRACT Ground deformation studies of volcanoes have provided much information on the pattern of flank movements. Mount Etna volcano, situated on the eastern coast of Sicily has grown in the vicinity the Malta escarpment probably linked on shore to the Timpe Fault System (TFS) dissecting the volcano's eastern flank. The eastern flank is, in addition to this regional faulting, subjected to gravitational spreading, as seaward horizontal displacements are constrained by geodetic studies. Therefore, the question arises how tectonic faulting and gravitational spreading of the Mount Etna eastern flank are related and how this complex deformation is associated with eruptive activity. Here we investigate the 2001 eruptive period in an attempt to elaborate the mutual influence of tectonic faulting, spreading and intrusion. Associated with this eruption, GPS and InSAR data revealed that the eastern flank has been affected by significant ground deformation, moreover the pattern of geodetically-detected ground displacements abruptly changed before, during and after the eruption. The pre-eruptive deformation (January to July 2001) is characterized by the displacement and subsidence of the lower part of the eastern flank affecting the TFS's footwall and hangingwall. The co-eruptive deformation (July to September 2001) is characterized by movement of the entire flank with stronger displacements at higher altitudes, and the post-eruptive deformation (September to October 2001) shows a similar displacement as during the pre-eruptive period, but with stronger displacements at lower altitudes. To better understand this changing behaviour, we reproduced Mount Etna volcano in a sandbox model and recorded its internal deformation with a digital image correlation technique. We considered the volcano morphology as a half ridge, and (1) defined an underlying weak decollement surface (silicone) to simulate gravitational spreading, (2) defined displacement of the Malta escarpment and hence of the TFS using a motor-controlled normal fault originating in the solid basement, and (3) forcefully intruded dikes along the axis of symmetry (N-S) that intend to push the eastern flank. Thus gravitational spreading and tectonic faulting were simulated concurrently with intermittent intrusions. Two main sets have been tested, first gravitational deformation (non-intruding period) followed by a period of intrusion together with normal faulting; and second an intrusion period followed by gravitational deformation together with normal faulting. The experiments showed that intrusive activity at Etna volcano change the intensity of spreading and affect displacement at the TFS. For instance, horizontal velocities at either side of the TFS are strongly affected by periods of shallow magmatic activity. Our experiments may help to explain the horizontal displacement changes found by the geodetic data associated with the 2001 eruptive cycle, including the pre-eruptive spreading, the dike intrusion event and the following eastern flank movements.

We carried out a study of seismicity and ground deformation occurred on Mount Etna volcano after the end of 2002-2003 eruption and before the onset of 2004-2005 eruption, recorded by the permanent local seismic network run by Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania and by geodetic surveys carried out in July 2003 and July 2004 on

ABSTRACT The Envisat mission extension beyond the end of 2010 allows to (a) operate the mission for an additional 3 years (until end of 2013 or early 2014) and (b) ensure the continuity of the maximum number of Envisat applications, with the exception of ASAR Interferometry. The change of orbit, indeed, degraded the interferometric capabilities. Nevertheless, the new orbit configuration of Envisat has been refined, in order to ensure that the InSAR baselines will be kept at a minimum value at specific latitude, around 38° North for descending passes and 38° South for ascending passes. Etna area (latitude 37.5 °) is favored by this new orbital configuration of Envisat, and the new orbital repeat cycle of 30 days (instead of 35) will ensure more frequent acquisitions. In the framework of the CAT-1. 5843, we continued to monitor the volcano by Envisat interferometry. In the last year Mt. Etna was characterized by several fire fountains episodes at the New South Eastern Crater (NSEC). In particular we analyzed a fire fountain episode occurred on 12 January which produced an eastward flowing lava field, within the Valle del Bove area and a large volcanic plume several kilometers high. The episode started at about 22:00 local time and ended at about 00:50 of 13 January (Behncke et al., internal report INGV-CT). The deformations recorded in the interferogram are relatively small and limited around the summit area, at elevations above the 1500-2000 m. The data modeling results detected a depressurizing source representing the emptying of the shallow magmatic reservoir. Furthermore the coherence analysis of interferometric products was able to well image the new lava field and the fallout deposit providing a new complementary mapping tool. These preliminary analyses are in good agreement with the data acquired by the monitoring systems managed by the Osservatorio Etneo of the INGV (GPS, tilt, seismic networks) and field surveys.

ABSTRACT Persistent inflation and long-period gravity fluctuations occurred at Mt Etna (Italy) during the time interval bounded by the 1991-93 and 2001 main flank eruptions. Several studies suggest that, since 1993 and before the 2001 eruption, a large amount of magma was stored at depth. Up to date, an integrated inversion of the available ground deformation and gravity data has not been attempted, in spite of the possibility of bringing new insight into the processes that led to the 2001 eruption. In this study we perform simultaneous, nonlinear inversion of gravity and ground deformation data collected at Mt. Etna between 1995 and 2000. We utilize a new inversion scheme that assumes bodies with a 3D free geometry to determine the best-fitting geometrical configuration of pressure and density sources. The latter are obtained through aggregating pressure and density point sources, until the best fit to the data is reached. The approach works in a step-by-step growth process that allows building very general geometrical configurations. Preliminary results indicate constancy in time of the position of pressure and mass sources, in spite of the different phases of activity displayed by the volcano during the period of interest. A fundamental result of this study is that pressure and mass sources are widely separated in space. In particular, pressure is found to have steadily increased in a volume below the northeastern sector of the volcano, while the observed gravity changes were due to mass changes within a volume centered below the southeastern sector of the volcano, at shallower depths. The neat separation between mass and pressure sources is a key feature which needs to be properly addressed in order to understand the processes which controlled the activity of Mt Etna during the studied period.

Twelve Years of Ground Deformation Studies on Mt. Etna Volcano Based on GPS Surveys Giuseppe Puglisi1, Pierre Briole2 and Alessandro Bonforte1 GPS (Global Positioning System) monitoring has been performed on Etna volcano since 1988, making this volcano one of those with ...

Abstract. In this paper we propose a complex network in order to model re-lationships among active volcanoes of the world. In literature it is well known that volcanoes separated by hundreds of kilometers frequently erupt in unison. These eruptions suggest there is a connection ...

Using eleven ascending PALSAR scenes acquired by the Japanese satellite ALOS over Etna, between January 2007 and September 2008, we produced a series of interferograms covering the volcano and surroundings, by using ROI-PAC software. We compare our results with ENVISAT interferograms covering the same period. The coherence is significantly higher than C-band and it is particularly high in the inhabited areas and on lava flows emplaced during last centuries, where local subsidence is observed on the most recent ones; important improvements in the coherency are also achieved on forested areas. L-band interferometric pairs having large baselines, up to 3 km, are still usable but the coherency significantly fall off, as the baseline increases. Deformation patterns are well measured, and the use of L-band dataset is particular useful in those cases where the coherency in C-band is usually low. This is the case, for instance, of the north-eastern sector of the volcano, where the large for...

Ground deformation occurring on Mount Etna from 1994 to 1995 is analyzed in this paper. This period was characterized by intense volcanic activity at the four summit craters, with frequent strombolian activity, fire fountains, and emplacement of several new lava flows. Four GPS ...

In this work, we analyse both the space-time evolution of seismic activity and ground deformation (by GPS data measurements) affecting Mt. Etna during the last thirteen years, with particular attention to the years following the 1991-1993 lateral eruption. After a short period of deflation following this eruption, ground deformation measurements indicate that during 1994-2000 the entire edifice underwent a marked inflation, which preceded the recent July-August 2001 lateral eruption. Careful analysis of the spatial pattern of the seismic energy release, since the second half of 1996, evidences some strict relationship to the GPS ground deformation behaviour, and both strongly support a link between magma-related mass changes at depth and associated stress and strain variations. This observed stress-strain pattern is clearly influenced by the regional tectonic and the NNW-SSE trending fault zone which plays a relevant role in the recent volcano dynamic, until the July-August 2001 lat...

The eruptive background of the July 2001 eruption at Mt. Etna, proved extremely complex and dynamic from the very beginning. The development of the ground defor- mation pattern due to the eruptive event was monitored through both GPS continuous measurements on network of permanent and static stations, and daily measurements both static and kinematic GPS, made by INGV-CT on geodetic

The July - August 2001 Mt Etna eruption has been studied using the DinSAR technique and monitored through both continuous GPS measurements on a network of permanent and static stations, as well as daily static and kinematic GPS measurements, made by INGV-CT, on ...