Geophysical surveys are carried out in the coastal area of Petrosino (southwestern Sicily) to study the time evolution of seawater contamination of the coastal aquifer, probably increased due to human impact. The overexploitation of the... more
Geophysical surveys are carried out in the coastal area of Petrosino (southwestern Sicily) to study the time evolution of seawater contamination of the coastal aquifer, probably increased due to human impact. The overexploitation of the aquifer, due to an intensive agricultural use has affected significantly the natural hydro-geochemical state of the basin. The study is based on a processing and integrated analysis of hydrogeological, geochemical and geophysical data. In particular in the last two years seasonal time-lapse electrical resistivity tomographies (ERT), new TDEM soundings and Multi-Analysis Surface Wave soundings (MASW) have been carried out. The interpretation of the total set of previously existing and new geophysical data made it possible to reconstruct a three-dimensional model of the electrical resistivity of the aquifer, aimed at defining the extent and geometry of the seawater intrusion. Furthermore, the execution of a series of high-resolution time-lapse electrical tomographies and a correlation analysis between geophysical measures and geo-chemical, geological and hydrogeological data allowed to discriminate the effects of the salt concentration in the groundwater and the porosity and saturation degree of the rock on the time variations of the measured electrical resistivity. Finally, the average porosity of the rocks forming the reservoir was determined.
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ABSTRACT
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ABSTRACT Export Date: 3 March 2014, Source: Scopus
ABSTRACT Export Date: 3 March 2014, Source: Scopus
A report is given of the activity of the Sea Land Group(a) concerning the CROP MARE II seismic project. In this experiment, jointly with near-vertical seismic data acquisition (NVR), the Sea Land Group acquired high-density wide-angle... more
A report is given of the activity of the Sea Land Group(a) concerning the CROP MARE II seismic project. In this experiment, jointly with near-vertical seismic data acquisition (NVR), the Sea Land Group acquired high-density wide-angle reflection/refraction data (WARR) in some offshore/on-shore configurations along the Italian coast. A concise and complete overview is given of the acquisition scheme, the processing techniques used and the problems connected with the acquisition and management of this kind of data. Our experience led us to get over the standard processing techniques commonly adopted in WARR and NVR seismics, setting up innovative Matlab procedures for data processing. Such a development was directed at an integrated use of smalland great-offset seismic signals for the optimisation of imaging and modelling of lithospheric structures.
The Calabrian Arc, Southern Italy, is characterised by the subduction of the Ionian lithosphere -since Middle Miocene- beneath the Tyrrhenian basin. The related Benioff zone is seismically active to a depth > 500 km. The tomoDD code... more
The Calabrian Arc, Southern Italy, is characterised by the subduction of the Ionian lithosphere -since Middle Miocene- beneath the Tyrrhenian basin. The related Benioff zone is seismically active to a depth > 500 km. The tomoDD code [Zhang and Thurber, 2003] was adopted to perform the tomography, using a set of 2463 earthquakes located in the window 14°30' E - 17°E and 37°N - 41°N, and recorded by seismic networks of the INGV in the period 1981-2005. Several inversions were performed using different selections of absolute and differential data obtained varying the maximum RMS and the threshold of the inter-event distance. Various synthetic and experimental tests were executed to evaluate the resolution and stability of the tomographic inversion. The inversions carried out for the synthetic and the restoration-resolution test [Zhao et al., 1992] were repeated several times with the same procedure used in the inversion of experimental data. The lack of bias in the models, relat...
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This paper introduces a new technique for clustering seismic events based on processing, in time-frequency domain, the waveforms recorded by seismographs. The detection of clusters of waveforms is performed by a k-means like algorithm... more
This paper introduces a new technique for clustering seismic events based on processing, in time-frequency domain, the waveforms recorded by seismographs. The detection of clusters of waveforms is performed by a k-means like algorithm which analyzes, at each iteration, the time-frequency content of the signals in order to optimally remove the non discriminant components which should compromise the grouping of waveforms. This step is followed by the allocation and by the computation of the cluster centroids on the basis of the filtered signals. The effectiveness of the method is shown on a real dataset of seismic waveforms.
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The northern coast of Sicily and its offshore area represent a hinge zone between a sector of the Tyrrhenian Basin, characterized by the strongest crustal thinning, and the sector of the Sicilian belt which has emerged. This hinge zone is... more
The northern coast of Sicily and its offshore area represent a hinge zone between a sector of the Tyrrhenian Basin, characterized by the strongest crustal thinning, and the sector of the Sicilian belt which has emerged. This hinge zone is part of a wider W-E trending right-lateral shear zone, which has been affecting the Maghrebian Chain units since the Pliocene. Seismological and structural data have been used to evaluate the seismotectonic behavior of the area investigated here. Seismological analysis was performed on a data set of about 2100 seismic events which occurred between January 1988 and October 2002 in the Southern Tyrrhenian Sea. This paper focuses in particular on a set of data relating to the period from 6th September 2002, including both the main shock and about 540 aftershocks of the Palermo seismic sequence. The distribution of the hypocenters revealed the presence of two main seismogenic zones. The events of the easternmost zone may be related to the Ionian lithos...
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The Calabrian Arc, Southern Italy, is characterised by the subduction of the Ionian lithosphere -since Middle Miocene- beneath the Tyrrhenian basin. The related Benioff zone is seismically active to a depth > 500 km. The tomoDD code... more
The Calabrian Arc, Southern Italy, is characterised by the subduction of the Ionian lithosphere -since Middle Miocene- beneath the Tyrrhenian basin. The related Benioff zone is seismically active to a depth > 500 km. The tomoDD code [Zhang and Thurber, 2003] was adopted to perform the tomography, using a set of 2463 earthquakes located in the window 14°30' E -
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The Northern Sicily and its Tyrrhenian off-shore are part of the Maghrebian chain, whose the architecture is the result of a multiple-phase tectonic history from Late Oligocene-Early Miocene to Present. The main structural features,... more
The Northern Sicily and its Tyrrhenian off-shore are part of the Maghrebian chain, whose the architecture is the result of a multiple-phase tectonic history from Late Oligocene-Early Miocene to Present. The main structural features, occurring from regional to outcrop scale, are represented by NW-SE to W–E striking right-lateral faults and by N–S to NE-SW striking left-lateral faults, both responsible of uplift and lowering respectively of restraining or releasing zones. With the aim to better define the seismotectonic model of this area, we carried out an integrated research, by means structural, geophysical and statistical analyses, in some key areas, placed both in the onshore and in the offshore northern Sicily sectors. On the first one the brittle strain partitioning related to a right-lateral simple shear zone has been reconstructed, on the second one the structural setting has been inferred from morpho-bathymetric and geological maps of the Southern Tyrrhenian basin.
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ABSTRACT Tidal gravity observations performed in the last few years, both at Mt Etna and Stromboli, have revealed the necessity of improving the tidal analysis in order to get the best corrected data for the detection of volcano related... more
ABSTRACT Tidal gravity observations performed in the last few years, both at Mt Etna and Stromboli, have revealed the necessity of improving the tidal analysis in order to get the best corrected data for the detection of volcano related signals. On Mt. Etna the sites are very close to each other and the expected tidal factors differences are negligible. It is thus useful to try to unify the tidal analysis results of the different data sets on a unique tidal model. In order to get the best model for the gravity data tide correction, we compared the results and finally we normalized all the estimated tidal factors with respect to the best data set. The change in time of the gravimeters sensitivity is also an important issue to be checked since it affects the quality of the data and thus the results of tidal analysis. Conversely, if a good tidal model is available, the sensitivity variations can be accurately reconstructed such as to retune observed tidal records with the synthetic tide, since the tidal parameters are assumed as constant. Subsequently, we tried to check if a tidal modulation exists on the heat flow beneath the gravity station, by using two temperature signals recorded inside and outside it. This analysis suggests an unexpected correlation between thermometric observations and some lunar tidal components.
In this paper we propose a clustering technique, based on the maximization of the likelihood function defined from the generalization of a model for seismic activity (ETAS model, (Ogata (1988))), iteratively changing the partitioning of... more
In this paper we propose a clustering technique, based on the maximization of the likelihood function defined from the generalization of a model for seismic activity (ETAS model, (Ogata (1988))), iteratively changing the partitioning of the events. In this context it is useful to apply models requiring the distinction between independent events (i.e. the background seismicity) and strongly correlated ones.
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ABSTRACT In this paper we propose a clustering technique set up to separate and find out the two main components of seismicity: the background seismicity and the triggered one. We suppose that a seismic catalogue is the realization of a... more
ABSTRACT In this paper we propose a clustering technique set up to separate and find out the two main components of seismicity: the background seismicity and the triggered one. We suppose that a seismic catalogue is the realization of a non homogeneous space–time Poisson clustered process, with a different parametrization for the intensity function of the Poisson-type component and of the clustered (triggered) component. The method here proposed assigns each earthquake to the cluster of earthquakes, or to the set of independent events, according to the increment to the likelihood function, computed using the conditional intensity function estimated by maximum likelihood methods and iteratively changing the assignment of the events; after a change of partition, MLE of parameters are estimated again and the process is iterated until there is no more improvement in the likelihood.
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... Giuseppe Giunta a , Corresponding Author Contact Information , E-mail The Corresponding Author , Dario Luzio b , Fabrizio Agosta c , Marco Calò b ... collision between African and European Plate, and then to the evolution of... more
... Giuseppe Giunta a , Corresponding Author Contact Information , E-mail The Corresponding Author , Dario Luzio b , Fabrizio Agosta c , Marco Calò b ... collision between African and European Plate, and then to the evolution of Tyrrhenian Basin ([Scandone, 1979], [Finetti and Del ...