GNGTS 2016 - Atti del 35° Convegno Nazionale

334 GNGTS 2016 S essione 2.2 boundary between the Gran Sasso and the Laga tectono-stratigraphic domains, marked by the Gran Sasso thrust. In the Santa Lucia area, placed within the Tronto River basin, surveys show the presence of a NE dipping monocline of arenaceous and arenaceous- pelitic lithotypes of the Messinian Laga formation; this structure is displaced to the west by a N240° dipping normal fault and crossed to the east by a N250° dipping thrust plane, belonging to the northernmost segment of the Gran Sasso thrust. On a local scale, the thrust is somewhere linked to low angle retro-verging compressive elements. This structural setting generates a widespread fracture pattern of bedrock lithotype giving rise to predisposing factors for amplification phenomena. The north eastern villages of the Capitignano municipality were built on sandstone deposits of the Laga formation, which constitute a N240° dipping monocline structure locally affected by compressive elements, like vertical or overturned strata. Instead, the main villages of the Capitignano municipality extend at the base of the north eastern mountain front of the Montereale basin (Chiarini et al. , 2014) and are crossed by the main basin fault (Capitignano fault). They mainly rest on Quaternary alluvial fan deposits referable to several depositional events Middle Pleistocene to Holocene in age. The Capitignano fault has been considered to be part of an active system (Boncio et al. , 2004; Galadini et al., 2000; Galadini and Messina, 2004), responsible for the January 16 event (Mw= 6) during the 1703 seismic sequence (Blumetti, 1995; Boncio et al., 2004). According to Lavecchia et al. (2012) it reactivated during the seismic sequence following the main shock at L’Aquila on April 6, 2009 and forms with the San Giovanni Fault the Montereale Fault System that behaves as an individual source capable to release strong earthquakes. At this time ISPRA is providing support to INGV for a mapping project (Civico et al. , 2016) and paleoseimological studies on the San Giovanni and Capitignano faults. Research carried out by ISPRAhas identified within the intermountain basin two sedimentary sub-basins (Piedicolle and Capitignano), separated by a threshold Moreover, the evaluation of the thickness and the geometry of the Quaternary sedimentary infilling has been performed through a 3D analysis of survey data, borehole logs and geophysical data (Chiarini et al. , 2014). Task planning. Within the DPC activities after the Central Italy earthquake of August 24, 2016, the Seismic Microzonation (Level 3) of Santa Lucia and Capitignano have been organized into the following interconnected tasks: Task 1: finding and storage into a GIS project of borehole logs and geotechnical and geophysical investigations; Task 2: geological, geomorphological and building damage assessment surveys and mapping at a 1: 5,000 scale; Task 3: elaboration of the technical-geological and seismically homogeneous microzones maps at 1:5,000 scale with related cross-sections; study of the seismic prone unstable areas Fig. 2 – Location map of the Capitignano-Paterno-Piedicolle areas.