Traces of the active Capitignano and San Giovanni faults (Abruzzi Apennines, Italy)

Abstract

We present a 1:20,000 scale map of the traces of the active Capitignano and San Giovanni faults in the area of the Montereale basin (central Apennines, Italy) covering an area of about 80 km 2 . Detailed fault mapping is based on high-resolution topography from airborne LiDAR imagery validated by extensive ground truthing and geophysical prospecting. Our analysis allowed the recognition of several features related to fault activity, even in scarcely accessible areas characterized by dense vegetation cover and rugged terrain. The identified fault traces run at the base of the NW-SE striking Montereale basin-bounding mountain front and along the base of the southwestern slope of the Monte Mozzano ridge, and have a length of about 12 and 8 km, respectively. Improving the knowledge of fault geometry is a critical issue not only for the recognition of seismogenic sources but also for surface fault hazard assessment and for local urban planning. The knowledge of the exact location of the fault traces is also crucial for the seismogenic characterization of the active faults by means of paleoseismological trenching.ARTICLE HISTORY

Evidence for Surface Faulting Earthquakes on the Montereale Fault System (Abruzzi Apennines, Central Italy)

“…Based on previous works on the Montereale area (Chiarini et al, ; Civico et al, ; Lavecchia et al, ) and on the present trenching study across one splay of the MFS, that is, San Giovanni fault, we summarize the following fault parameters.…”

“…We found the most favorable conditions (i.e., narrow zone of deformation, young deposits) for paleoseismological trenching investigations along the SGF (Figures and ) at the mouth of the Grande creek valley, at the northern end of the Mount Mozzano ridge. We used subsurface imaging from shallow geophysical campaigns (Civico et al, ) to infer the location of fault zones and thus for trench positioning. Furthermore, the selected site was an opportunity to merge the information acquired by us in 2005 from a temporary exposure of the SGF fault zone within a nearby quarry (Figure ).…”

“…The MFS has a complex fault structure at the surface, and it is composed of the subparallel, down‐to‐the‐west Capitignano fault (CF) and San Giovanni fault (SGF) main faults with an average strike of N145° (Figure ), characterized by a normal slip kinematic with a minor left‐lateral component (Chiarini et al, ; Civico et al, ; Lavecchia et al, ). In Blumetti (), the CF was pointed out as recently active based on the occurrence of fault scarps on Middle Pleistocene alluvial fan deposits; later on, Lavecchia et al () considered the CF and the SGF to belong to the same fault system acting as an independent extensional source on the basis of instrumental seismicity.…”

“…The Montereale intermontane basin has been the subject of specific Quaternary geology studies and of focused research on the activity of the CF and SGF during the survey of the 1:50,000 scale official geological map (Chiarini et al, ). Recently, Civico et al () accurately mapped the traces of the CF and SGF using LiDAR Digital Terrain Model and field data (Figure ), providing also geomorphological and shallow geophysical constraints testifying to their repeated activity during the Late Pleistocene‐Holocene period. However, the CF and SGF behavior and interaction have been only partially defined, their Holocene activity not documented, and their seismic potential not assessed.…”

“…(a) Map of the active traces of the Capitignano (CF) and San Giovanni faults (SGF) in the area of the Montereale basin (central Apennines, Italy; modified after Civico et al, ). The inset in the top right shows a schematic geological section across the Montereale intermountain basin (vertical exaggeration 2X; A‐A′ trace reported in the map as white line).…”