Digital terrestrial and aero-photogrammetric mapping for identification and characterization of a co-seismic ground deformation by normal faulting of the 1781 Cagli earthquake (Northern Apennines – Italy)

The North-Western sector of the Monte Nerone anticline and surrounding areas were studied in order to find some ground features related to the historical earthquake occurred in 1781, taking the name from the nearby town of Cagli. After a preliminary historical study of this earthquake and interpretation of aero-photos and satellite imagery, we focused our work on the already mapped normal faults of the official cartography (Cagli 1:50,000 and Geological maps of the Marche Region at 1:10,000). After a ground based digital mapping (using tablet pc, GPS and QGIS) and a UAV survey we could map a system of normal fault cutting Jurassic to Paleocene carbonatic succession and Neogene terrigenous units of the Umbria Marche Succession. The 3D info e data obtained using photogrammetric software (Agisoft Metashape) were imported in geological modelling software (MOVE, Rhinoceros) to build a 3D model with geological data available. We could characterize and interpret the fault system in the frame of the regional geology, in order to bring new information for seismic hazard of the Apennine sector.