A multidisciplinary approach to the seismotectonics of the Lunigiana and Garfagnana extensional basins (Northern Tuscany, Italy)

New geological and morpho-structural surveys are integrated with seismological and seismic reflection data in order to define the active and potentially seismogenic sources of the Lunigiana and Garfagnana extensional basins (Tuscany, Northern Italy). The seismogenic role of the E-W-striking transfer fault between the Lunigiana and Garfagnana basins, located at the northern termination of the Apuane metamorphic core, and its possible association with a number of historical earthquakes are also discussed

Imaging the three-dimensional architecture of the Middle Aterno basin (2009 L’ Aquila earthquake, Central Italy) using ground TDEM and seismic noise surveys: preliminary results

We present preliminary results from a multidisciplinary geophysical approach ap- plied to the imaging of the three-dimensional architecture of the Middle Aterno basin, close to the epicentral area of the 2009 L’Aquila earthquake (central Italy). We collected several time domain electromagnetic soundings (TDEM) coupled with seismic noise measurements focu- sing on the characterization of the bedrock/in ll interface. Our preliminary results agree with existing geophysical data collected in the area, and show that the southeastern portion of the basin is characterized by a deepening of the Mesozoic-Tertiary bedrock down to a depth of more than 450 m. We found that a joint use of electromagnetic and seismic methods signi - cantly contributes in obtaining new insights on the 3D geometry of the Middle Aterno basin. Moreover, we believe that our combined approach based on TDEM and noise measurements can be adopted to investigate similar geological settings elsewhere.PublishedPescina (AQ), Italy2T. Tettonica attiva3T. Pericolosità sismica e contributo alla definizione del rischio7A. Geofisica di esplorazioneope

Seismic noise measurements along the slope of the L'Aquila terrace

L'Aquila downtown (Central Italy) suffered strong damages during the April 6th 2009 Mw 6.3 earthquake. In particular many collapses and strong damages on buildings have been observed near the southern edge of the L'Aquila downtown. L'Aquila is bounded southward by the Aterno river valley along a steep scarp. The downtown is settled on a calcareous terrace, mainly composed of a Pleistocene stiff calcareous breccia over-imposed to ancient lacustrine sediments. The upper portion of the L'Aquila breccia in the area of Via XX Settembre, which borders the southern edge of the top of the morphological terrace of L'Aquila downtown, is irregularly affected by the presence of residual soils known as "red soils" or filling material. The continental deposits are characterized by a velocity inversion at a depth ranging from few tens up to one hundred meters. We performed extensive ambient vibration measurements along the south-western slope of the L'Aquila terrace, where some RC structures without anti-seismic design were heavily damaged during the Mw 6.3 mainshock. Noise measurements were conducted along several sections starting from the top of the terrace toward the base of the Aterno river valley. The aim was to investigate the relationship between horizontal-to-vertical amplitude spectra ratio (H/V method) with the geological and geomorphological variations existing along the flanks of the L'Aquila terrace. We also performed noise measurements within some open underground caves that are present along the slope of the calcareous terrace. We integrate our geophysical data with the available geological, geotechnical and geophysical data, performed for the seismic microzonation and the reconstruction of the damaged buildings. We find that the resonance frequency is varying from about 0.6 to 1 Hz for sites at the top of terrace and in proximity of the Aterno river valley, respectively. Larger amplitude of the resonance peak is observed at sites on the top of the terrace rather than the measurements performed at the base. Additionally, the H/V curves at the bottom of the L'Aquila terrace show an amplification in a broader frequency band. The variation in the H/V shapes, moving along the flanks of the L'Aquila terrace, is mainly related to a different behavior of the vertical component. Indeed the vertical recordings show a spectral minimum shifted at higher frequency for measurements nearby the Aterno river

Results from shallow geophysical investigations in the northwestern sector of the island of Malta

We performed geophysical investigations in the northwestern sector of the island of Malta to reconstruct velocity-depth models and provide shear-wave velocity profiles. We have chosen two sites, one located in Rabat (Malta) and another in the Golden Bay area. We used both active (seismic and electrical 2D-tomography, Multichanel Analysis of Surface Waves – MASW) and passive (2D arrays and single-station measurements using ambient noise) geophysical methods. Consistently with previous studies performed in this part of Malta, we have found that both sites are characterised by site resonance in the frequency range 1-2 Hz as an effect of the local lithostratigraphic succession that shows an impedance contrast at about 60-90 m depth. This resonance effect can have important implications on both seismic hazard as well as seismic risk evaluation of the region since the amplified frequency range coincides with the resonance frequencies typical of 5–10 storey buildings which are very diffuse in the Maltese Islands, especially after intense recent urbanization.Published41-484T. Sismologia, geofisica e geologia per l'ingegneria sismicaJCR Journa

Imaging the three-dimensional architecture of the Middle Aterno basin (2009 L’Aquila earthquake, Central Italy) using ground TDEM and seismic noise surveys: preliminary results

We present preliminary results from a multidisciplinary geophysical approach applied to the imaging of the threedimensional architecture of the Middle Aterno basin, close to the epicentral area of the 2009 L’Aquila earthquake (central Italy). We collected several time domain electromagnetic soundings (TDEM) coupled with seismic noise measurements focusing on the characterization of the bedrock/infill interface. Our preliminary results agree with existing geophysical data collected in the area, and show that the southeastern portion of the basin is characterized by a deepening of the Mesozoic-Tertiary bedrock down to a depth of more than 450 m. We found that a joint use of electromagnetic and seismic methods significantly contributes in obtaining new insights on the 3D geometry of the Middle Aterno basin. Moreover, we believe that our combined approach based on TDEM and noise measurements can be adopted to investigate similar geological settings elsewhere.PublishedPescina (AQ)2T. Tettonica attivaope

Imaging the three-dimensional architecture of the Middle Aterno basin (2009 L’Aquila earthquake, Central Italy) using ground TDEM and seismic noise surveys: preliminary results

We present preliminary results from a multidisciplinary geophysical approach applied to the imaging of the threedimensional architecture of the Middle Aterno basin, close to the epicentral area of the 2009 L’Aquila earthquake (central Italy). We collected several time domain electromagnetic soundings (TDEM) coupled with seismic noise measurements focusing on the characterization of the bedrock/infill interface. Our preliminary results agree with existing geophysical data collected in the area, and show that the southeastern portion of the basin is characterized by a deepening of the Mesozoic-Tertiary bedrock down to a depth of more than 450 m. We found that a joint use of electromagnetic and seismic methods significantly contributes in obtaining new insights on the 3D geometry of the Middle Aterno basin. Moreover, we believe that our combined approach based on TDEM and noise measurements can be adopted to investigate similar geological settings elsewhere

A database of the coseismic effects following the 30 October 2016 Norcia earthquake in Central Italy

We provide a database of the coseismic geological surface effects following the Mw 6.5 Norcia earthquake that hit central Italy on 30 October 2016. This was one of the strongest seismic events to occur in Europe in the past thirty years, causing complex surface ruptures over an area of >400 km 2. The database originated from the collaboration of several European teams (Open EMERGEO Working Group; about 130 researchers) coordinated by the Istituto Nazionale di Geofisica e Vulcanologia. The observations were collected by performing detailed field surveys in the epicentral region in order to describe the geometry and kinematics of surface faulting, and subsequently of landslides and other secondary coseismic effects. The resulting database consists of homogeneous georeferenced records identifying 7323 observation points, each of which contains 18 numeric and string fields of relevant information. This database will impact future earthquake studies focused on modelling of the seismic processes in active extensional settings, updating probabilistic estimates of slip distribution, and assessing the hazard of surface faulting

H/V dal rumore sismico ambientale: Tool efficace per lo studio delle cavità?

Si presentano casi studio utilizzando il metodo H/V per lo studio di cavità naturali o antropiche. Misure di rumore sismico sono state effettuate in diversi siti, acquisendo dati contemporaneamente all'interno e sopra cavità. Lo scopo del presente lavoro è capire sperimentalmente se con misure di rumore sismico in superficie è possibile avere indicazioni sulla presenza di cavità sepolte. Sebbene le curve H/V calcolate al di sopra delle cavità abbiano spesso mostrato ampiezze minori di 1 nel range delle alte frequenze (> 20 Hz), i risultati sperimentali non sembrano univoci e ulteriori studi sia numerici che sperimentali sono necessariPublishedL'Aquila3T. Pericolosità sismica e contributo alla definizione del rischiorestricte