Update of the Italian Seismic Catalog (2003-2007) Catalogo della Sismicità Italiana CSI v2.0

Earthquake catalogues are the basic tools that furnish parametric data for seismic hazard evaluation, studies on evolution of seismic sequences and earthquake occurrence. The INGV seismic network covers a large part of the italian region and it is complemented by several regional permanent network handled by other institutions. CSI results from the combination of INGV seismic bulletin with bulletins produced by other institutions. To update CSI from previous release to version 2.0 we collected seismic bulletins sent to INGV from, at present, 12 institutions managing permanent seismic networks during 2003-2007. Procedures to convert different file formats to PHS format as input files of Hypoellipse program have been setup that also perform preliminary checks on possible errors. To correctly merge different seismic bulletins it is mandatory to have a strict control on phase associations. To do this, additional procedures to identify earthquakes external to the interest area and wrong associations of different earthquakes based on geographic control network associations and stations' residuals after event location have been produced. About 35,000 eartquakes, a mean value of ~6600 earthquakes per year, with more than 600.000 P-phase arrivals and more then 250,000 S-phase arrivals have been collected and located with Hypoellipse. To enhance final locations quality we applied a multiple location approach and then selected the best among several calculated hypocentres for each event. Location criteria are based on the use of two different weighting schemes for stations' distance combined with several reference regional 1D velocity models. Native Ml Magnitudes from 2003 to 2007 are retrieved and then associated to the corresponding event from INGV bulletin. When native Ml is not available, Ml based on regression law by Castello et al. 2007, is attributed. The update of CSI catalog, also due to the strong improvement of the INGV seismic network between 2005 and present, offers a more complete image of the Italian seismicity and a new important reference for further studies on the evolution of this region and earthquake occurrence

SEISMIC ANISOTROPY AND ITS RELATION WITH FAULTS AND STRESS FIELD IN THEVAL D'AGRI (SOUTHERN ITALY).

Shear-wave splitting is measured at 17 seismic stations deployed in the Val DAgri by INGV, which recorded local back-ground seismicity from May 2005 to June 2006 . The splitting results suggest the presence of an anisotropic upper crust (max hypocentral depth 15.5 km). The dominant fast polarisation direction strikes NW-SE parallel to the Apennines orogen and is approximately parallel to the maximum horizontal stress in the region and also parallel to the strike of the main normal faults in the Val DAgri. The size of the delay times, average is 0.1 second suggests 4.5% shear-wave velocity anisotropy. At stations located at the North West portion of the deployment average delay times are larger on the order of 0.2s. These parameters agree with an interpretation of seismic anisotropy in terms of the Extensive-Dilatancy Anisotropy model which considers the rock volume to be pervaded by fluid-saturated microcracks aligned by the active stress field. We cannot completely rule out the contribution of aligned macroscopic fractures as the cause of the shear wave anisotropy even if the parallel shear-wave polarisations we found are diagnostic of transverse isotropy with a horizontal axis of symmetry. This symmetry is commonly explained by parallel stress-aligned microcracks

The deep structure of the Larderello-Travale geothermal field (Italy) from integrated, passive seismic investigations

AbstractWe report the preliminary results from a project (GAPSS-Geothermal Area Passive Seismic Sources), aimed at testing the resolving capabilities of passive exploration methods on a well-known geothermal area, namely the Larderello-Travale Geothermal Field (LTGF). Located in the western part of Tuscany (Italy), LTGF is the most ancient geothermal power field of the world. GAPSS consisted of up to 20 seismic stations deployed over an area of about 50 x 50 Km. During the first 12 months of measurements, we located more than 2000 earthquakes, with a peak rate of up to 40 shocks/day. Preliminary results from analysis of these signals include: (i) analysis of Shear-Wave-Splitting from local earthquake data, from which we determined the areal distribution of the most anisotropic regions; (ii) local-earthquake travel-time tomography for both P- and S-wave velocities; (iii) telesismic receiver function aimed at determining the high-resolution (<0.5km) S-velocity structure over the 0-20km depth range, and seismic anisotropy using the decomposition of the angular harmonics of the RF data-set; (iv) S-wave velocity profiling through inversion of the dispersive characteristics of Rayleigh waves from earthquakes recorded at regional distances. After presenting results from these different analyses, we eventually discuss their potential application to the characterisation and exploration of the investigated area

A multi-sensor approach for coastal area monitoring

This study proposes a multi-sensor approach to promote and effective coastal area monitoring strategy over areas that include critical infrastructures, e.g.; on-shore and off-shore oil/gas extraction platforms and groundwater reservoirs. The monitoring strategy includes both sea-side and land-side observations using remotely sensed measurements. With respect to the land-side, multi-temporal differential Interferometric Synthetic Aperture Radar (DInSAR) and Global Positioning System (GPS) techniques are exploited to monitor of subsidence phenomena along on-shore hydrocarbon and groundwater reservoirs, where surface deformations can be correlated to the extraction / pumping of resources from / into the subsoil. This is a non-trivial issue, which aims at improving the standards of security for the production / exploitation / storage of underground resources, as well as providing / implementing ad-hoc procedures for the monitoring of interested. With respect to the sea-side, effective SAR techniques are exploited to take benefit of multi-polarization SARs to observe oil/gas rigs/platforms and to observe oil discharges close to the oil extraction sites.PublishedCopenaghen, Denmark7A. Geofisica per il monitoraggio ambientale e geologia medic

Passive seismology and deep structure in central Italy

n the last decade temporary teleseismic transects have become a powerful tool for investigating the crustal and upper mantle structure. In order to gain a clearer picture of the lithosphere-asthenosphere structure in peninsular Italy, between 1994 and 1996, we have deployed three teleseismic transects in northern, central, and southern Apennines, in the framework of the project GeoModAp (European Community contract EV5V-CT94–0464). Some hundreds of teleseisms were recorded at each deployment which lasted between 3 and 4 months. Although many analyses are still in progress, the availability of this high quality data allowed us to refine tomographic images of the lithosphere-asthenosphere structure with an improved resolution in the northern and central Apennines, and to study the deformation of the upper mantle looking at seismic anisotropy through shear-wave splitting analysis. Also, a study of the depth and geometry of the Moho through the receiver function technique is in progress. Tomographic results from the northernmost 1994 and the central 1995 teleseismic experiments confirm that a high-velocity anomaly (HVA) does exist in the upper 200–250 km and is confined to the northern Apenninic arc. This HVA, already interpreted as a fragment of subducted lithosphere is better defined by the new temporary data, compared to previous works, based only on data from permanent stations. No clear high-velocity anomalies are detected in the upper 250 km below the central Apennines, suggesting either a slab window due to a detachment below southern peninsular Italy, or a thinner, perhaps continental slab of Adriatic lithosphere not detectable by standard tomography. We found clear evidence of seismic anisotropy in the uppermost mantle, related to the main tectonic processes which affected the studied regions, either NE–SW compressional deformation of the lithosphere beneath the mountain belt, or arc-parallel asthenospheric flow (both giving NW–SE fast polarization direction), and successive extensional deformation ( E–W trending) in the back-arc basin of northern Tyrrhenian and Tuscany. Preliminary results of receiver function studies in the northern Apennines show that the Moho depth is well defined in the Tyrrhenian and Adriatic regions while its geometry underneath the mountain belt is not yet well constrained, due to the observed high complexity.Published479-4934T. Sismicità dell'ItaliaJCR Journa

The contribution of the Istituto Nazionale di Geofisica 1 e Vulcanologia (INGV) to 2 “Adria LithosPHere investigAtion (ALPHA)” active seismic experiment

During the winter 2012, from 20 January to 4 February, the German oceanographic FS METEOR cruise (M86/3) took place in the central-southern Adriatic Sea in the frame of “Adria LithosPHere InvestigAtion” (ALPHA [Kopp et al., 2013]). The primary goal of the project was high-resolution tomographic imaging of the crust and lithospheric mantle underneath the southern Adriatic Sea, the Apulia eastern margin and the external zone of the Dinaric thrust-belt by collecting offshore-onshore seismic data along three multi-fold wide-aperture profiles. The definition of reliable velocity models of the Adriatic lithosphere was considered crucial for a better understanding of the structure, fragmentation, geodynamic evolution, and seismotectonics of the Adria-Apulia microplates. The ALPHA Project was coordinated by Helmholtz Centre for Ocean Research Kiel, Germany (GEOMAR), former Leibniz Institute of Marine Sciences (German: Leibniz-Institut für Meereswissenschaften, IFM-GEOMAR) and conducted in close cooperation with different European institutions of Germany, Albania, Croatia, Italy and Montenegro. The Istituto Nazionale di Geofisica Vulcanologia (INGV) participated by deploying land stations along two transects in the Apulia and Gargano Promontory to extend westwards the seismic profiles. The primary goal was to record shallow-to-deep seismic phases travelling along the transition between the Adriatic basin and the Apulia foreland. In this paper we present the field work related to the two Italian onshore transects, the recorded data, and the processing flow developed to highlight crustal and mantle refractions and wide-angle reflections