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Moretti M.,Italian National Institute of Geophysics and Volcanology | Abruzzese L.,Italian National Institute of Geophysics and Volcanology | Augliera P.,Italian National Institute of Geophysics and Volcanology | Azzara R.,Italian National Institute of Geophysics and Volcanology | And 75 more authors.
Quaderni di Geofisica | Year: 2013

On May 20th 2012 (Sunday) an earthquake (ML 5.9) hit Northern Italy at 02:03 UTC,. The National Seismic Network [Amato and Mele, 2008; Delladio, 2011] of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) located the hypocenter below the Po Valley in the Emilia region (44.89° N, 11.23° E, 6.3 km depth). Just after the mainshock, the INGV structure of rapid response for seismic emergency has been activated in order to install a temporary seismic network as a complementary of existing permanent network in the epicentral area. The INGV installed 44 temporary stations, ten of these transmitting in real time to seismic monitoring room in Rome. Further 38 temporary seismic stations (16 provided by National Civil Protection Department - DPC, 8 provided by the National Institute of Oceanography and Experimental Geophysics - OGS and 14 provided by French colleagues) have been installed in the epicentral area. The final configuration was obtained by coordination among INGV and other agencies. The Centro Operativo Emergenza Sismica (COES) [Moretti et al., 2010a] was activated relatively late, on June 8th 2012, because the INGV branch in Bologna located close to the epicentral area, was in the early days fulfilling the COES tasks. The COES ensured continuous and direct communication with the DPC officers present in the epicentral area. At the same time, the structure has been proposed as logistic support to all the INGV colleagues engaged in activities in the epicentral area (mobile seismic networks, EMERSITO, GPS, EMERGEO, QUEST) and to the service dedicated to the education and information promoted in favor of affected populations, civil defense operators as well as rescue volunteers. In this paper we will describe the activities carried out during the first month of emergency, the method and timing of the intervention, and finally the structures involved. © 2013 INGV Istituto Nazionale di Geofisica e Vulcanologia.

Moretti M.,Italian National Institute of Geophysics and Volcanology | Cattaneo M.,Italian National Institute of Geophysics and Volcanology | Pondrelli S.,Italian National Institute of Geophysics and Volcanology | Margheriti L.,Italian National Institute of Geophysics and Volcanology | And 41 more authors.
Quaderni di Geofisica | Year: 2013

At the end of September 2011 a simulation test of rapid-response to a seismic emergency was conducted in the frame of the current agreement between the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Civil Protection Agency of the Emilia Romagna, with the objective of evaluating the level of preparedness reached in the emergency procedures established by INGV and the regional Civil protection Agency for a major earthquake. The simulation involved more than 50 researchers and technicians working in the offices and in the field in the pretended epicentral area. The INGV staff involved belongs to different INGV offices (Ancona, Arezzo, Bologna, Irpinia, Milan, Pisa and Rome). The preparation of the test event was based on the past experiences of real emergencies, primarily the long emergency in L'Aquila territory in 2009 [Margheriti et al., 2010; 2011; Moretti et al., 2011c], with a look to the new instances from INGV researchers and from outside (for example, instances of the Civil Protection). Despite the unexpected and the inevitable mistakes and the challenging efforts of putting together many different competences, with the need of satisfying the commitments made with the Civil Protection Agency of the Region of Emilia Romagna, it was immediately clear that the experience would improve our skills both from a professional and a human point of view. It was an important opportunity to interact and engage activities with colleagues to learn new things. This experience was then of paramount importance in the management of the seismic emergency in May 2012 in the Po Valley [Moretti et al., 2012]. © 2013 INGV Istituto Nazionale di Geofisica e Vulcanologia.

Cigolini C.,University of Turin | Di Martino M.,National institute for astrophysics | Laiolo M.,University of Turin | Coppola D.,University of Turin | And 2 more authors.
Meteoritics and Planetary Science | Year: 2012

The twin Arkenu circular structures (ACS), located in the al-Kufrah basin in southeastern Libya, were previously considered as double impact craters (the "Arkenu craters")The ACS consist of a NE (Arkenu 1) and a SW structure (Arkenu 2), with approximate diameters of about 10kmThey are characterized by two shallow depressions surrounded by concentric circular ridges and silica-impregnated sedimentary dikes cut by local faultsOur field, petrographic, and textural observations exclude that the ACS have an impact originIn fact, we did not observe any evidence of shock metamorphism, such as planar deformation features in the quartz grains of the collected samples, and the previously reported "shatter cones" are wind-erosion features in sandstones (ventifacts)Conversely, the ACS should be regarded as a "paired" intrusion of porphyritic stocks of syenitic composition that inject the Nubia Formation and form a rather simple and eroded ring dike complexStock emplacement was followed by hydrothermal activity that involved the deposition of massive magnetite-hematite horizons (typical of iron oxide copper-gold deposits)Their origin was nearly coeval with the development of silicified dikes in the surroundingsPlugs of tephritic-phonolitic rocks and lamprophyres (monchiquites) inject the Nubian sandstone along conjugate fracture zones, trending NNW-SSE and NE-SW, that crosscut the structural axis of the basin. © 2012 The Meteoritical Society.

Matassoni L.,Fondazione Prato Ricerche | Fiaschi A.,Fondazione Prato Ricerche | Silengo M.C.,University of Pisa | Silengo M.C.,University of Florence | And 2 more authors.
Open Geosciences | Year: 2015

In this paperwe describe a microzonation survey carried out at a mountain Municipality (Piteglio, Northern Apennines). We complemented the available data by conducting 106 microtremor measurements for Horizontal-to- Vertical Spectral Ratio (HVSR) analysis. Most of the data concern the three major rural villages (Piteglio-Prataccio, Popiglio and Prunetta). Furthermore, we installed a field mobile seismic station at two of the major villages, in order to obtain earthquakes recordings. The HVSR analysis shows amplification effects due to eluvial or colluvial deposits overlying the seismic bedrock, even for areas previously mapped as bedrock outcrops. Most zones characterized by sandstone outcrops show peaked HVSR traces. This observation could be also interpreted in terms of a topographic effect. In contrast, areas characterised by chaotic materials (olistostrome) generally exhibit a flat HVSR. Other areas of seismic amplification were identified on alluvial and landslide deposits. Results byHVSR analysis arewell correlated with available data from geo-technical and geophysical surveys, thus allowing to invert HVSRs for the physical properties of the subsoil. Subsoil properties can thus be extrapolated also in areas for which only measurements of seismic noise are available. Moreover, noise HVSRs agree well with those from earthquakes recorded at the different selected sites. © 2015 L. Matassoni et al.

Piccinini D.,Italian National Institute of Geophysics and Volcanology | Piana Agostinetti N.,Dublin Institute for Advanced Studies | Saccorotti G.,Italian National Institute of Geophysics and Volcanology | Fiaschi A.,Fondazione Prato Ricerche | And 2 more authors.
Journal of Geodynamics | Year: 2014

Within the central Mediterranean geodynamic puzzle, the seismotectonic processes of the northern sector of the Apennines are still under debate. In this framework, we conducted a careful examination of seismic catalogues for five years of instrumental seismicity located in the eastern sector of the Tosco-Emiliano Apennines. In our study, we merge two separate seismic bulletins, derived from a small- and a large-aperture seismic network. The joint analysis of the seismic phases of both catalogues allows us to improve event locations and to assess their hypocentral depths. After re-location using a regional velocity model, we found that the spatial distribution of hypocenters follows characteristic patterns at the southwestern and northeastern sides of the chain. Such distribution exhibits a marked axial offset in correspondence of the Livorno-Sillaro Line (LSL), a NE-SW trending lithological discontinuity previously interpreted in terms of a transform zone. Basing on this evidence, and on additional observations related to the morphology of the area, we hypothesise the LSL to represent the shallow manifestation of a discontinuity affecting the whole lithospheric thickness, i.e. a incipient tear fault dislocating the subducting slab. © 2014 Elsevier Ltd.

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