HR: 0804h
AN: NS11E-0838    [Abstracts]
TI: Seismic Imaging of the Vallo di Diano Fault System (Southern Italy) by Integrating High- Resolution Reflection Profiles and Shallow Tomography
AU: * Bruno, P
EM: bruno@ov.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Via Diocleziano 328, Napoli, 80124, Italy
AU: Improta, L
EM: improta@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Roma 1, Via di Vigna Murata 605, Roma, 00143, Italy
AU: Castiello, A
EM: castiello@ov.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Via Diocleziano 328, Napoli, 80124, Italy
AU: De Rosa, D
EM: derosa@ov.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Via Diocleziano 328, Napoli, 80124, Italy
AU: Villani, F
EM: villani@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Roma 1, Via di Vigna Murata 605, Roma, 00143, Italy
AU: Amicucci, L
EM: amicucci@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Roma 1, Via di Vigna Murata 605, Roma, 00143, Italy
AU: Di Fiore, V
EM: difiore@iamc..cnr.it
AF: Consiglio Nazionale delle Ricerche (CNR), Istituto per l'Ambiente Marino e Costiero, Calata Porta di Massa, Napoli, 80133, Italy
AU: Pierdominici, S
EM: pierdominici@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Roma 1, Via di Vigna Murata 605, Roma, 00143, Italy
AU: Montone, P
EM: montone@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Roma 1, Via di Vigna Murata 605, Roma, 00143, Italy
AU: Rapolla, A
EM: antonio.rapolla@unina.it
AF: Università  di Napoli, "Federico II", Dipartimento Scienze della Terra, Largo San Marcellino 10, Napoli, 80138,
AU: Rapolla, A
EM: antonio.rapolla@unina.it
AF: C.U.G.RI. Consorzio inter Universitario per la previsione e prevenzione dei Grandi Rischi, via Ponte don Melillo, Fisciano (SA), 84084, Italy
AB: The NW-striking, SW-dipping range-bounding extensional faults (Vallo di Diano Fault System, VDFS) drive the evolution of the Vallo di Diano basin (southern Italy). Despite of structural and geomorphic investigations, the Late Pleistocene activity of this complex fault system is still a matter of debate. We have interpreted seismic commercial profiles (down to 2 sec TWT) suggesting a 1000 m maximum infill thickness, with depositional geometries controlled by the VDFS" activity probably since late Pliocene times. Geomorphological analysis in the central sector of the basin revealed unreported small scarps aligned with the VDFS and affecting two late Pleistocene fans. With the scope to define the shallower portion of the VDFS and to assess its possible recent activity, we get two parallel high-resolution seismic profiles crossing the aforementioned scarps. The first is 1200 m long and crosses a 30 m high scarp affecting a middle Pleistocene fan. The second is 400 m long and crosses two small scarps affecting a late Pleistocene fan. Seismic profiles were collected with a non-conventional dense/extended-offset geometry using 168 geophones and a Minivib source. The two high-quality stack sections obtained show coherent reflections, together with two high-resolution P-velocity images from first-arrival travel-time tomography. Stack sections depict the subsurface structure up to 1 km depth, while the tomographic models image the shallower portion (40-50 m). The high-resolution profile presents four distinct seismic units separated by unconformities, where the shallowest unit shows sub-horizontal high-frequency low-amplitude reflectors overlapping an articulated erosion surface. Strong and coherent reflectors below this unconformity can be interpreted as two separate alluvial fans with southward progradational patterns. The third and deeper unconformity is represented by a low-frequency and continuous reflector downlapped by the alluvial fans to the south. The very-high resolution profile also shows evidence of truncations in the upper reflective portion, here interpreted as a high-angle SW-dipping normal fault. It is not clear if the fault displaces shallower portions of the alluvial fans, however the fault position well matches a surface scarp. These features correlate with deeper reflection truncations on the stack sections and partially with the observed scarps suggesting recent faulting activity in the area. Now, we are going to acquire a new data set along the south- eastern part of the main tectonic alignment to define its shallower branch.
DE: 0935 Seismic methods (3025, 7294)
DE: 0994 Instruments and techniques
DE: 8109 Continental tectonics: extensional (0905)
DE: 9335 Europe
SC: Near-Surface Geophysics [NS]
MN: 2007 Fall Meeting