We provide a database of the coseismic geological surface effects following the Mw 6.5 Norcia earthquake that hit central Italy on 30 October 2016. This was one of the strongest seismic events to occur in Europe in the past thirty years, causing complex surface ruptures over an area of >400 km2. The database originated from the collaboration of several European teams (Open EMERGEO Working Group; about 130 researchers) coordinated by the Istituto Nazionale di Geofisica e Vulcanologia. The observations were collected by performing detailed field surveys in the epicentral region in order to describe the geometry and kinematics of surface faulting, and subsequently of landslides and other secondary coseismic effects. The resulting database consists of homogeneous georeferenced records identifying 7323 observation points, each of which contains 18 numeric and string fields of relevant information. This database will impact future earthquake studies focused on modelling of the seismic processes in active extensional settings, updating probabilistic estimates of slip distribution, and assessing the hazard of surface faulting.

On 24 August 2016, a Mw 6.0 normal‐faulting earthquake struck central Italy, causing about 300 fatalities and heavy damage. A geological survey collected the coseismic effects observed at the surface in order to evaluate two competing hypotheses about their nature: surface faulting versus gravitational deformation. We find that the most significant geological effect is a 5.2 km long alignment of ground ruptures along the Mount Vettore Fault System. These ruptures are independent from lithology, topography, morphology, and change in slope and exhibit an average dip‐slip displacement of ~13 cm. Geometry, kinematics, and dimensional properties of this zone of deformation strongly lead us to favor the primary surface faulting hypothesis that fits well the predicted estimates from experimental scaling law relationships. Our study provides relevant hints for surface faulting in extensional domains, contributing to implement the worldwide database of the moderate earthquakes.

The Pian Grande di Castelluccio (PGC) basin is the main Quaternary depocenter of the Mt.Vettore-Mt. Bove normal fault system (VBFS), responsible for the 30 October 2016 M w 6.5 Norcia earthquake (central Italy). Coseismic surface faulting through the basin attests the occurrence of active splays of the seismogenic master fault; thus, we explore the subsurface basin structure to infer the long-term behavior of the VBFS. We integrate electrical resistivity tomography (ERT), time domain electromagnetic soundings (TDEM), and horizontal-to-vertical spectral ratios of ambient seismic vibrations (HVSR) along a transect crossing the surface ruptures. The ERT models provide high-resolution details of three shallow fault zones. One-dimensional resistivity models from TDEM and HVSR frequency peaks suggest abrupt steps in the top bedrock caused by previously unknown faults and indicate an infill thickness of up to~300 m. We also analyze shear wave splitting of S phases (fast direction φ and delay time δt) from local earthquakes recorded during our surveys to better constrain the fracture field and the properties of the inferred fault zones. We relate the retrieved pattern of fault-parallel φ, and the associated larger δt, to the main and secondary faults in the upper crust and to the cracks or shear fabric in the damage zones of the active splays. The PGC basin is due to the interference of an older N30°striking fault system subsequently crosscut by the N150°striking VBFS, which is currently active, seismogenic, and capable of rupturing the surface during M > 6 earthquakes. 2009; Burbank & Anderson, 2011). Hence, the basins' geometry and depositional architecture provide basic VILLANI ET AL.26

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We applied a joint survey approach integrating time domain electromagnetic soundings and single‐station ambient vibration surveys in the Middle Aterno Valley (MAV), an intermontane basin in central Italy and the locus of the 2009 L'Aquila earthquake. By imaging the buried interface between the infilling deposits and the top of the pre‐Quaternary bedrock, we reveal the 3‐D basin geometry and gain insights into the long‐term basin evolution. We reconstruct a complex subsurface architecture, characterized by three main depocenters separated by thresholds. Basin infill thickness varies from ~200–300 m in the north to more than 450 m to the southeast. Our subsurface model indicates a strong structural control on the architecture of the basin and highlights that the MAV experienced considerable modifications in its configuration over time. The buried shape of the MAV suggests a recent and still ongoing predominant tectonic control by the NW‐SE trending Paganica‐San Demetrio Fault System (PSDFS), which crosscuts older ~ENE and NNE trending extensional faults. Furthermore, we postulate that the present‐day arrangement of the PSDFS is the result of the linkage of two previously isolated fault segments. We provide constraints on the location of the southeastern boundary of the PSDFS, defining an overall ~19 km long fault system characterized by a considerable seismogenetic potential and a maximum expected magnitude larger than M 6.5. This study emphasizes the benefit of combining two easily deployable geophysical methods for reconstructing the 3‐D geometry of a tectonically controlled basin. Our joint approach provided us with a consistent match between these two independent estimations of the basin substratum depth within 15%.