Starting from 24 August 2016, a long seismic sequence, including nine Mw > 5.0 earthquakes, struck a wide area of the Central Italy. A large amount of geological, geodetic, and seismological data envisages a complex system of NNW‐SSE trending, seismogenic normal faults. These active tectonic structures are well known at the surface and consistent with previous seismotectonic studies. In order to improve the comprehension of the seismotectonic framework of this seismic sequence, we provide a novel reconstruction of the subsurface geology of the area close to the Norcia Mw 6.5 mainshock (30 October 2016), based on previously unpublished seismic reflection profiles and available geological data. All the data have been synthesized along a 47 km long, WSW‐ENE trending geological cross section, interpreted down to a depth of 12 km. Comparing the subsurface geological model with the available seismological data, we find that the majority of seismicity is confined within the sedimentary sequence and does not penetrate the underlying basement. The basement has been constrained at depths of 8 to 11 km and coincides with the cutoff of the seismicity. We have also traced the trajectories of the seismogenic normal faults activated during this seismic sequence, reconciling the high‐angle (dip>65°) normal faults exposed at the surface, with their angle (dip < 50°) at hypocentral depths. The results of this study may be useful for better understanding the rheological properties of the seismogenic rock volume, as well as the coseismic deformations of the topographic surface observed by geodetic techniques and field mapping.

The 2.08-Ma Cerro Galán Ignimbrite (CGI) represents a >630-km 3 dense rock equivalent (VEI 8) eruption from the long-lived Cerro Galán magma system (∼6 Ma). It is a crystal-rich (35-60%), pumice (<10% generally) and lithic-poor (<5% generally) rhyodacitic ignimbrite, lacking a preceding plinian fallout deposit.

Estimates of pyroclastic flow emplacement temperatures in the Cerro Galán ignimbrite and Toconquis Group ignimbrites were determined using thermal remanent magnetization of lithic clasts embedded within the deposits. These ignimbrites belong to the Cerro Galán volcanic system, one of the largest calderas in the world, in the Puna plateau, NW Argentina. Temperature estimates for the 2.08-Ma Cerro Galán ignimbrite are retrieved from 40 sites in 14 localities (176 measured clasts), distributed at different distances from the caldera and different stratigraphic heights. Additionally, temperature estimates were obtained from 27 sample sites (125 measured clasts) from seven ignimbrite units forming the older Toconquis Group (5.60-4.51 Ma), mainly outcropping along a type section at Rio Las Pitas, Vega Real Grande. The paleomagnetic data obtained by progressive thermal demagnetization show that the clasts of the Cerro Galán ignimbrite have one single magnetic component, oriented close to the expected geomagnetic field at the time of emplacement. Results show therefore that most of the clasts acquired a new magnetization oriented parallel to the magnetic field at the moment of the ignimbrite deposition, suggesting that the clasts were heated up to or above the highest blocking temperature (T b ) of the magnetic minerals (T b =580°C for magnetite;

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The edifice of Stromboli volcano gravitationally collapsed several times during its volcanic history (> 100 ka-present). The largest Holocene event occurred during the final stage of the Neostromboli activity (similar to 13-5 ka), and was accompanied by the emplacement of phreatomagmatic and lahar deposits, known as the Secche di Lazzaro succession. A stratigraphic and paleomagnetic study of the Secche di Lazzaro deposits allows the interpretation of the emplacement and the eruptive processes. We identify three main units within the succession that correspond to changing eruption conditions. The lower unit (UA) consists of accretionary lapilli-rich, thinly bedded, parallel- to cross-stratified ash deposits, interpreted to indicate the early stages of the eruption and emplacement of dilute pyroclastic density currents. Upward, the second unit (UB) of the deposit is more massive and the beds thicker, indicating an increase in the sedimentation rate from pyroclastic density currents. The upper unit (UC) caps the succession with thick, immediately post-eruptive lahars, which reworked ash deposited on the volcano's slope. Flow directions obtained by Anisotropy of Magnetic Susceptibility (AMS) analysis of the basal bed of UA at the type locality suggest a provenance of pyroclastic currents from the sea. This is interpreted to be related to the initial base-surges associated with water-magma interaction that occurred immediately after the lateral collapse, which wrapped around the shoulder of the sector collapse scar. Upward in the stratigraphy (upper beds of UA and UB) paleoflow directions change and show a provenance from the summit vent, probably related to the multiple collapses of a vertical, pulsatory eruptive column

The emplacement temperatures of three ignimbrites belonging to the 4.6-ka Fogo A plinian eruption sequence in São Miguel Island (Azores, Portugal) were determined using partial thermal remanent magnetization (pTRM) of lithic clasts and reflectance (Ro%) of charcoal fragments embedded within the deposits and collected at the same localities close to each other. The Fogo A sequence is characterised by a complex stratigraphy consisting of a thick plinian deposit interbedded with two intraplinian ignimbrites (here named “pink” and “black” intraplinian ignimbrite, respectively) and capped by a final ignimbrite (here named “dark brown” ignimbrite). A total of 140 oriented lithic clasts from the three ignimbrites were collected from 15 localities distributed along the northern and southern flanks of the volcano. The pTRM analyses show different paleomagnetic behaviours, which correspond to different emplacement temperatures of the ignimbrites. The emplacement temperatures of the pink and black intraplinian ignimbrites inferred from pTRM analysis were respectively ≥400 and ≥600 °C; the temperatures of the dark brown ignimbrite are lower, estimated between 300 and 350 °C. Thermal estimations of three key sites were compared with the results of the analysis of reflectance (Ro%) measured on eight specimens derived from charcoal fragments collected from the pink intraplinian ignimbrite and the dark brown ignimbrite. Results indicate Ro% values between 1.61 and 1.37 for the pink intraplinian ignimbrite, whereas fragments collected from the dark brown ignimbrite show Ro% values between 0.85 and 0.50. No charred wood was found in the black intraplinian ignimbrite. Ro% values indicate that charcoal fragments in the pink intraplinian ignimbrite reached temperatures of 380–460 °C, whereas the Ro% values of the dark brown ignimbrite indicate slightly lower temperatures of 330–350 °C. TRM and Ro% results are comparable and validate the use of both methods. Greatest accuracy in the determination of emplacement temperatures of ignimbrites is achieved when both methods can be applied at the same locations

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The Peperino Albano (approximately 19-36 ka old) is a phreatomagmatic pyroclastic flow deposit, cropping out along the slopes of the associated Albano maar (Colli Albani volcano, Italy). The deposit exhibits lateral and vertical transitions from valley pond to veneer facies, as well as intracrater facies. We present the results of a paleomagnetic study of thermal remanent magnetization (TRM) of the lithic clasts of the Peperino Albano ignimbrite that provide quantitative estimates of the range of emplacement temperatures across the different facies of the ignimbrite. Emplacement temperatures estimated for the Peperino Albano ignimbrite range between 240°and 350°C, with the temperatures defined in the intracrater facies being generally lower than in the valley pond and veneer facies. This is possibly due to the large size of the sampled clasts in the intracrater facies which, when coupled with low temperature at the vent, were not completely heated throughout their volume during emplacement. The emplacement temperatures derived from the paleomagnetic results are in good agreement with the presence of un-burnt plants at the base of the ignimbrite, indicating that the temperature of the pyroclastic flow was lower than the temperature of ignition of wood. Paleomagnetic results from the Peperino Albano confirm the reliability of the paleomagnetic approach in defining the thermal history of pyroclastic flow deposits.