Abruzzi region (central Italy) producing vast damage in the L'Aquila town and surroundings. In this paper we present the location and geometry of the fault system as obtained by the analysis of main shock and aftershocks recorded by permanent and temporary networks. The distribution of aftershocks, 712 selected events with M L ! 2.3 and 20 with M L ! 4.0, defines a complex, 40 km long, NW trending extensional structure. The main shock fault segment extends for 15-18 km and dips at 45°to the SW, between 10 and 2 km depth. The extent of aftershocks coincides with the surface trace of the Paganica fault, a poorly known normal fault that, after the event, has been quoted to accommodate the extension of the area. We observe a migration of seismicity to the north on an echelon fault that can rupture in future large earthquakes.

We present the first high-quality catalog of early aftershocks of the three mainshocks of the 2016 central Italy Amatrice-Visso-Norcia normal faulting sequence. We located 10,574 manually picked aftershocks with a robust probabilistic, non-linear method achieving a significant improvement in the solution accuracy and magnitude completeness with respect to previous studies. Aftershock distribution and relocated mainshocks give insight into the complex architecture of major causative and subsidiary faults, thus providing crucial constraints on multi-segment rupture models. We document reactivation and kinematic inversion of a WNW-dipping listric structure, referable to the inherited Mts Sibillini Thrust (MST) that controlled segmentation of the causative normal faults. Spatial partitioning of aftershocks evidences that the MST lateral ramp had a dual control on rupture propagation, behaving as a barrier for the Amatrice and Visso mainshocks, and later as an asperity for the Norcia mainshock. We hypothesize that the Visso mainshock re-activated also the deep part of an optimally oriented preexisting thrust. Aftershock patterns reveal that the Amatrice Mw5.4 aftershock and the Norcia mainshock ruptured two distinct antithetic faults 3–4 km apart. Therefore, our results suggest to consider both the MST cross structure and the subsidiary antithetic fault in the finite-fault source modelling of the Norcia earthquake.

On July, 12, 2001, Mt. Etna experienced a sudden increase of seismic activity heralding one of the most intense eruptions of the past 30 years. Between July 12 and July 18, when the eruption started, thousands of small magnitude earthquakes occurred and were recorded by a dense seismic network run by the Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania (INGV‐CT). Hypocentral depths of earthquakes were very shallow, mostly located above 3 km b.s.l. and clustered near the summit area. The high quality seismic dataset gives us the unique opportunity to study the process of magma migration before the eruption. In this study we present the three‐dimensional earthquake locations and the velocity structure obtained by a tomographic inversion. The shallowness of seismicity allowed us to enhance the details of the structure beneath the summit craters, in a volume poorly defined by previous tomographic studies. The presence of a high Vp‐body previously observed at Mt. Etna is confirmed at shallow depth beneath the southeastern part of the summit area. The earthquakes preceding the eruption onset concentrated at its western border. A low Vp/Vs anomaly is found at 0–1 km depth, just at the top of the volume where the magma intruded before the eruption. This anomalous zone can be considered as molten material wealthy in gas. The relocated seismicity occurs in a cylinder below the vents activated along the fracture system and exhibited an upward migration until the eruption. All these results show evidence for the emplacement of a near‐vertical dyke striking about N‐S and a few kilometres south of the summit craters.

In the Ionian Sea (central Mediterranean) the slow convergence between Africa and Eurasia results in the formation of a narrow subduction zone. The nature of the crust of the subducting plate remains debated and could represent the last remnants of the Neo‐Tethys ocean. The origin of the Ionian basin is also under discussion, especially concerning the rifting mechanisms as the Malta Escarpment could represent a remnant of this opening. This subduction retreats toward the south‐east (motion occurring since the last 35 Ma) but is confined to the narrow Ionian basin. A major lateral slab tear fault is required to accommodate the slab roll‐back. This fault is thought to propagate along the eastern Sicily margin but its precise location remains controversial. This study focuses on the deep crustal structure of the eastern Sicily margin and the Malta Escarpment. We present two two‐dimensional P wave velocity models obtained from forward modeling of wide‐angle seismic data acquired onboard the R/V Meteor during the DIONYSUS cruise in 2014. The results image an oceanic crust within the Ionian basin as well as the deep structure of the Malta Escarpment, which presents characteristics of a transform margin. A deep and asymmetrical sedimentary basin is imaged south of the Messina strait and seems to have opened between the Calabrian and Peloritan continental terranes. The interpretation of the velocity models suggests that the tear fault is located east of the Malta Escarpment, along the Alfeo fault system.

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