Local seismic response studies in the north-western portion of the August 24th, 2016 Mw 6.0 earthquake affected area. The case of Visso village (Central Apennines).

In this work, we investigate the possible causes of the differential damaging observed in Visso village (Central Apennines, about 28 km north from the August 24th, 2016 Mw 6.0 earthquake epicenter). Following insights from the available geological cartography at 1:10.000 scale, a preliminary geophysical survey has been performed in the damaged area in order to constrain geometries and extent of the subsoil lithotypes. Then, these results have been used to retrieve a Vs profile close to the most heavily damaged buildings. This latter has been used as input for a numerical analysis aimed at deriving the motion at the ground level in the study area. In particular, a linear equivalent simulation has been performed by means of EERA code and the waveform has been obtained convolving the time history recorded during the August 24th, 2016 mainshock at Spoleto Monteluco (SPM) site. Our preliminary results indicate a possible correlation of damaging to the thickness and shape of the geological units. Nevertheless, further analyses are necessary to highlight any 2D basin and / non- linear soil behaviour effects in order to compare them to the intrinsic buildings vulnerability, according to the EMS98 guidelines

Paleoseismic evidence of five magnitude 7 earthquakes on the Norcia fault system in the past 8,000 years (Central Italy)

Many large-magnitude faults (6.5≤ Mw ≤7.2) of the Italian Apennines are characterized by multi-century return times, so historical sources may have missed their last earthquake or other predecessors. Hence, even in Italy, where seismic catalogs are among the most comprehensive and time-extensive worldwide, there is a need for complementary studies that might fill the lack of historical information and enhance the knowledge concerning the recurrence times of destructive earthquakes. As paleoseismology is the discipline that can do this, in this study, we present results collected in five new trenches opened along the 33-km-long Norcia fault system (central Apennines) where, in addition to the historically known 1703 earthquake (Mw 6.9), we uncovered indications of four Holocene predecessor, with a recurrence time of 1,825 ± 420 years. Considering also the paleoseismic results already published on the nearby Mt Vettore fault system (2016 earthquake of Mw 6.6), we guess that now the seismic hazard of this region could be assessed more robustly

A web-based GIS (web-GIS) database of the scientific articles on earthquake-triggered landslides

Over the last 2 decades, the topic of earthquake-triggered landslides (EQTLs) has shown increasing relevance in the scientific community. This interest is confirmed by the numerous articles published in international, peer-reviewed journals. In this work we present a database containing a selection of articles published on this topic from 1984 to 2021. The articles were selected through a systematic search on the Clarivate™ Web of Science™ Core Collection online platform and were catalogued into a web-based GIS (web-GIS), which was specifically designed to show different types of information. After a general analysis of the database, for each article the following aspects were identified: the bibliometric information (e.g. author(s), title, publication year), the relevant topic and sub-topic category (or categories), and the earthquake(s) addressed. The analysis allowed us to infer general information and statistics on EQTLs (e.g. relevant methodological approaches over time and in relation to the scale of investigation, most studied events), which can be useful to obtain a spatial distribution of the articles and a general overview of the topic.</p

A reappraisal of the 1599 earthquake in Cascia (Italian Central Apennines). Hypothesis on the seismogenic source

In this study, we investigate a little-known earthquake that struck Cascia and its environs (Central Italian Apennines) in 1599, causing 50 casualties and the destruction and abandonment of several settlements. As in current seismic catalogues the characterization of this event is based on the anonymous account of a single source, we conducted research using public and private archives and libraries that allow recovering many unpublished contemporary accounts of the earthquake. This information permitted a more detailed evaluation of the macroseismic effects and a doubling of the number of intensity datapoints, resulting in a more robust earthquake epicentral parameters. Next, we conducted a geological field survey within the newly defined mesoseismic area aimed at finding possible evidence of active tectonics, likely faults with indications of recent movements and with an attitude fitting both the 1599 highest intensity distribution and the regional stress field. We found evidence for Holocene surface faulting along the Cascia and Mount Alvagnano faults that we consider responsible for the 1599 earthquake, and possibly also for a twin event in 1979 and the much stronger Norcia earthquake in 1703

Middle Pleistocene fluvial incised valleys from the subsoil of the centre of Rome: facies, stacking pattern and controls on sedimentation

A review and correlation of borehole data, mostly from a recent survey of drilling in Rome (Palatino Hill and Fori Romani), and outcrops studies have allowed to reconstruct the stratigraphic architecture of the subsoil. Fluvial lithofacies of the ancient Tiber River system are recognized, which fill three high relief incised valleys of Middle Pleistocene age within of which well dated pyroclastites occur. These valleys constitute portions of the low rank/high frequency depositional sequences (PG4, PG5 and PG6) forming the Middle Pleistocene to Holocene composite/high rank Ponte Galeria Depositional Sequence (Milli et al, in press). The latter represents the most recent stratigraphic unit of the Roman Basin. From a lithostratigraphic point of view the low rank sequences have a good correspondence with the Villa Glori, Fosso del Torrino and Quartaccio Synthems (Funiciello & Giordano, 2008) and are correlated to MIS 14-13, 12-11, 10-9 respectively. Valleys are elongated in N-S direction, and each of them has dimensions comparable to the tributaries valleys developing within the low rank Late Pleistocene-Holocene Tiber Depositional Sequence (Milli et al. in press): 1-2 km in width and up to 50 m in thickness. They are well entrenched into the substratum that is composed of Pliocene-Lower Pleistocene marine clay and Lower-Middle Pleistocene fluvial sediments and pyroclastites. The investigated valley segments are located some 20 km upstream from the coeval shorelines, nevertheless they show an internal stacking pattern of facies recording base level changes, in turn related to the Quaternary climatic and high frequency/amplitude sea level fluctuations. Each valley infill shows at the base a 10 m thick and laterally continuous body of amalgamated pebbles and sands forming a braided channel belt, deposited under low accommodation conditions and correlated with late lowstand and early transgressive phases. It follows a 20-30 m thick intermediate portion showing sandy-silty deposits attributed to sinuous channel belt, and laterally confined by muddy floodplain deposits, often rich in organic matter (transgressive phase). On the top, the channel sandy facies tend to widen and grade laterally to pedogenized floodplain mud. The three recognized incised valleys are organized into a compound-composite stack that records their progressive entrenchment and westward migration, in response to regional moderate uplift, to lateral supply from pyroclastic flows sourced by Colli Albani from SE, and to differential erodibility of the substratum

The awakening of the dormant Mount Vettore fault (2016 Central Italy earthquake,Mw 6.6). Paleoseismic clues on its millennial silences

The Mount Vettore normal fault ruptured between August and October 2016, sourcing three earthquakes of Mw 6.2, 6.1, and 6.6. The first one caused the death of 299 people, while the entire sequence reached the highest macroseismic intensity levels in Italy since the catastrophic 1915 Fucino event (Mw 7.1). This fault was known to be one of the historically dormant faults of the Italian Apennines, and its sudden activation, not preceded by any foreshocks, has caught people and scientists off guards. We describe here the results from three new paleoseismic trenches opened across splays of the main antithetic fault that ruptured at surface on 30 October together with the 30‐km‐long Mount Vettore master fault. Data account for six surface faulting events since 9 ka, with a return time of 1.8 ± 0.3 kyr. The penultimate, probably stronger earthquake occurred in Late Roman times, perhaps in 443 AD, when also Rome suffered damage to its monumental buildings. Once again, paleoseismology turns out to be a powerful tool in seismic hazard assessment, especially for earthquakes that recur hundreds or thousands of years apart