View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Earth-prints Repository SITE EFFECTS “ON THE ROCK”: THE CASE OF CASTELVECCHIO SUBEQUO (L’AQUILA, CENTRAL ITALY) Marzorati S.1, Ladina C.1, Falcucci E.2, Gori S.2, Saroli M.3, Ameri G.4, Galadini F.2 1 Istituto Nazionale di Geofisica e Vulcanologia, Centro Nazionale Terremoti 2 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Roma1 3 Dipartimento di Meccanica, Strutture, Ambiente e Territorio, Università di Cassino 4 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Milano-Pavia Corresponding author: Simone Marzorati, Istituto Nazionale di Geofisica e Vulcanologia, Centro Nazionale Terremoti, Sede di Ancona, Strada Cameranense 1, 60131 Passo Varano (AN), Italy, email:
[email protected] Abstract The April 6, 2009 L’Aquila earthquake was responsible for an “anomalous”, relatively high degree of damage (i.e. Is 7 MCS scale) at Castelvecchio Subequo (CS). Indeed, the village is located at source-to-site distance of about 40 km, and it is surrounded by other inhabited centres to which considerably lower intensities, i.e. Is 5-6, have been attributed. Moreover, the damage was irregularly distributed within CS, being mainly concentrated in the uppermost portion of the old village. Geophysical investigations (ambient seismic noise and weak ground motions analyses) revealed that site effects occurred at CS. Amplifications of the ground motion, mainly striking NE-SW, have been detected at the uppermost portion of the carbonate ridge on which the village is built. Geological/structural and geomechanical field surveys defined that the CS ridge is affected by sets of fractures, joints and shear planes – mainly roughly NW-SE and N-S trending – that are related to the deformation zone of the Subequana valley fault system and to transfer faults linking northward the mentioned tectonic feature with the Middle Aterno Valley fault system.