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At Mt. Etna (Italy), volcano‐tectonic earthquakes produce impressive surface faulting despite their moderate magnitude (M < 5.5), with historically well‐documented ruptures featuring end‐to‐end lengths up to 6–7 km. The 26 December 2018, Mw 5.0 earthquake represents the strongest event of the last 70 years, with ground ruptures extending for 7.5 km along the Fiandaca fault, a partially hidden structure in the volcano's eastern flank. Field data collected by the EMERGEO Working Group (INGV) are here integrated with high‐resolution photogrammetric surveys and geological‐morphological observations to enable a detailed structural analysis and to reconstruct the morphotectonic process of fault growth. The deformation zone develops in a transtensional regime and shows a complex pattern, consisting of brittle structures arranged in en‐échelon scale‐invariant overlapping systems. Offsets and kinematics vary along the strike due to a major bend in the fault trace. We reconstructed a prevailing right‐lateral displacement in the northern section of the fault and a dextral oblique slip in the southern one (max 35 cm); the dip‐slip component increases southward (max 50 cm) and overall resembles the along‐strike pattern of the long‐term morphological throw. The kinematic analysis indicates a quasi‐rigid behavior of the two fault blocks and suggests a geological model of rupture propagation that explains both the location of the seismic asperity in the northern section of the Fiandaca fault and the unclamping in the southern one. These findings are used to propose a conceptual model of the fault, representing insights for local fault‐based seismic hazard assessment. Key Points: The pattern of the 2018 rupture is characterized by scale‐invariant overlapping systems of structures organized in a hierarchical wayThe along‐strike distribution of the coseismic vertical displacement mimics the pattern of the long‐term morphological throw of the faultFindings constrain fault behavior and maximum expected magnitude as possible inputs for local fault‐based seismic hazard assessment [ABSTRACT FROM AUTHOR]

We provide the first 3‐D resistivity image of the Pian Grande di Castelluccio basin, the main Quaternary depocenter in the hangingwall of the Mt.Vettore–Mt. Bove normal fault system (VBFS), responsible for the October 30, 2016 Mw 6.5 Norcia earthquake (central Italy). The subsurface structure of the basin is poorly known, and its relation with the VBFS remains debated. Using the recent Fullwaver technology, we carried out a high‐resolution 2‐D transect crossing the 2016 coseismic ruptures coupled with an extensive 3‐D survey with the aim of: (a) mapping the subsurface of the basin‐bounding splays of the VBFS and the downdip extent of intrabasin faults; (b) imaging the infill and pre‐Quaternary substratum down to ∼1 km depth. The 2‐D resistivity section highlights under the coseismic ruptures a main dip‐slip fault zone with conjugated splays. The 3‐D resistivity model suggests that the basin consists of two depocenters (∼300 and ∼600 m deep, respectively) filled with silty sands and gravels (resistivity <300 Ωm), bounded and cross‐cut by NNE‐, WNW‐, and NNW‐trending faults with throws of ∼200–400 m. We hypothesize that the NNE‐trending system acted during the early basin development, followed by NNW‐trending and currently active splays of the VBFS that overprint pre‐existing structures and locally control the infill architecture. Moreover, beneath the basin we detect a shallow NW‐dipping blind fault. The latter is likely a hangingwall splay of the adjacent regional Mts. Sibillini Thrust, which may have been partly involved in the rupture process of the Norcia mainshock. Key Points: We show the first 3‐D shallow resistivity image of the Mw 6.5 Norcia earthquake fault system and its main Quaternary hangingwall basinThe mainshock fault system overprints NNE‐ and WNW‐trending faults that promoted the complex evolution of the Castelluccio hangingwall basinWe detect two main depocenters, 300 and 500–600 m deep, and a low‐angle fault to the south‐east of the basin, likely related to thrusting [ABSTRACT FROM AUTHOR]

Key Points: We analyze the surface ruptures of the 30 October 2016 Mw 6.5 Norcia normal‐faulting earthquake in central ItalyThe heterogeneity of surface slip, with peaks up to 2.10 m, is controlled by the coseismic rupture process at depthThe scaling properties and the complexity of surface slip reveal processes of fault segmentation and strain localization The study of coseismic surface ruptures provides insights into earthquakes dynamics and fault growth processes. We analyze the surface faulting related to the seismic sequence that hit central Italy in 2016–2017, focusing on the ruptures caused by 30 October 2016 Mw 6.5 Norcia earthquake. They are located on the NW trending normal fault splays of the Mount Vettore‐Mount Bove fault system (VBFS), forming a fracture network made of hundreds of strands striking N135–160°. The surface rupture length for this event is ~22 km, with average surface slip of ~0.44 m and peak of ~2.10 m. The collected coseismic slip vectors yield an average N233° trending extension, consistent with the local structural setting and seismological data. Surface slip displays cumulative frequency‐size distributions of rupture length and offset that follow power law and exponential scaling over 2 orders of magnitude, respectively. We observe strain localization on a few major fault splays of the VBFS, causing a markedly asymmetric along‐strike slip profile, with a high gradient to the southeast. The ~5‐km‐long Cordone del Vettore fault accounts for 40% of the overall coseismic surface slip. We infer that the heterogeneous slip at depth, coupled with the highly segmented nature of the VBFS and its interference with thrusts and adjacent active normal faults, has control over the pattern of surface faulting. For the Norcia earthquake, a robust scaling of surface slip area with rupture length accounts for extreme slip peaks over relatively short ruptures, which we envisage may be typical of the VBFS long‐term growth. [ABSTRACT FROM AUTHOR]