GNGTS 2016 - Atti del 35° Convegno Nazionale

518 GNGTS 2016 S essione 3.1 first is about 1 km long and was recorded using 8 seismic units, 192 geophones (5 m spacing, 10 m between the shots along the array). The receiver array of the second line is 96 m (with an eastward end-spread configuration of the sources), and it was collected using 2 seismic units and 48 receivers (distance 2 m). The latter profile is 360 m long and a number of three seismic recorders plus 72 geophones were used for its acquisition. The SEGY files have been treated by editing coordinates and elevations and defining a common datum. Then, such lines and a DEM (Tarquini et al. , 2007, 2012) were imported in the MOVE software (www.mve.com ) to provide a pseudo-3D interpretation of the local geological structures (Fig. 2). A time-to-depth conversion of the seismic lines have been successively performed, using a constant velocity value of 2500 m/s. The seismic facies description was based on reflector parameters as geometry, amplitude strength (high or low), continuity, and qualitative reflection frequency, all of which can be described in qualitative terms. This led to recognize 3 main seismo-stratigraphic units (A, B, C): one shallow and poorly resolved unit (from 0 to 50-70 ms) (A), an intermediated well resolved unit (B) with sub-horizontal reflectors interrupted between the CDP 98 and 178 (from 70 to 250 ms) and a lower well resolved unit (C) with a general south dipping of a few degrees. In addition, we have also integrated stratigraphic information collected from 11 borehole data which have been drilled in the study area between June 2010 and August 2013 (see Amoroso et al. , 2010 for further details about the boreholes) (Fig. 1). These boreholes have been drilled to final depths ranging between 53 (S8) and 300 m (S2) with the maximum depth investigated lying at 407 meters a.s.l. Almost all these boreholes (all excluding S3 and S4 sites), drilled the L’Aquila breccia which, considering local silty levels, showed thicknesses ranging between 7 and 70 meters. Only the S7 borehole did not intercept the Calabrian alluvial silty and sandy sequence, while only the S3 borehole encountered the Fig. 1 – Aerial photo of downtown L’Aquila. The three seismic lines and the location of the borehole data are reported.