Rapid Mapping of Landslides Induced by Heavy Rainfall in the Emilia-Romagna (Italy) Region in May 2023

Heavy rainfall is a major factor for landslide triggering. Here, we present an inventory of 47,523 landslides triggered by two precipitation episodes that occurred in May 2023 in the Emilia-Romagna and conterminous regions (Italy). The landslides are manually mapped from a visual interpretation of satellite images and are mainly triggered by the second rainfall episode (16–17 May 2023); the inventory is entirely original, and the mapping is supplemented with field surveys at a few selected locations. The main goal of this paper is to present the dataset and to investigate the landslide distribution with respect to triggering (precipitation) and predisposing (land use, lithology, slope and distance from roads) factors using a statistical approach. The landslides occurred more frequently on steeper slopes and for the land use categories of “bare rocks and badlands” and woodlands. A weaker positive correlation is found for the lithological classes: silty and flysch-like units are more prone to host slope movements. The inventory presented here provides a comprehensive picture of the slope movements triggered in the study area and represents one of the most numerous rainfall-induced landslide inventories on a global scale. We claim that the inventory can support the validation of automatic products and that our results on triggering and predisposing factors can be used for modeling landslide susceptibility and more broadly for hazard purposes

An integrated interdisciplinary approach to evaluate potentially toxic element sources in a mountainous watershed

Potentially toxic elements (PTEs, i.e., Cd, Ni, Cr) and their source apportionment in waters are of major environmental concern. Different approaches can be used to evaluate PTEs sources in environment, but single-way approaches are often limited and can easily fail. PTEs sources apportionment should include the evaluation of geochemical background and spatiotemporal trends analyses. We propose an integrated approach, and we apply it to a mountain catchment in the Italian central Alps, where ultramafic terranes crop out. We collected water and glacial sediment samples during the melting season. Then, we analyzed major ions and PTEs in waters, and we quantified the total PTEs load in sediments through acid digestion. Data were then processed through spatial and temporal trends analysis, clustering of variables and the evaluation of partition between the different compartments. We found a high geochemical background of part of the PTEs, consistently with results from other areas worldwide on mafic and ultramafic terranes (high concentrations of Ni, Cr and Fe), while we identified an additional atmospheric deposition source for Zn, Cd and Ag. Also, redundant observations on Cu, As and Pb indicated a possible mixed source. This study elucidates the need for an integrated approach to avoid unnecessary or misleading assumptions in the PTE\u2019s source appointment. A single-way approach application, in fact, can fail in understanding element source in a complicated and dynamic compartment like surface water

New stratigraphic and structural evidence for Late Pleistocene surface faulting along the Monte Olimpino Backthrust (Lombardia, N Italy)

We summarize some preliminary results achieved during the investigations conducted for the CARG Project, geological sheet n. 75 “Como”, i.e. the analysis of the Quaternary evolution of the “Monte Olimpino Backthrust” and the evaluation of its seismogenic activity. Cross-border field mapping between Ticino (CH) and Lombardia (IT) resulted in the finding of new outcrops (Borgo Vico site, in the north-western sector of the urban area of Como) located along the front of the Monte Olimpino Backthrust, that allowed to recognize evidence for Late Pleistocene reverse surface faulting along this structure. At Borgo Vico, a clastic Tertiary unit, the Villa Olmo Conglomerate, intercalated in the Chiasso Fm. of Early Oligocene age, is thrust over a Late Pleistocene fluvioglacial and glacio-lacustrine sequence (Comerci et alii, 2007). Until now, the Monte Olimpino Backthrust was supposed by most authors to have been active until Tortonian times. Sileo et alii (2007) inferred a Pliocene activity and proposed, based on geomorphic evidence, that fault displacement was still taking place during Pleistocene. However, this is the first time that Pleistocene activity along the Monte Olimpino Backthrust has been documented by unequivocal tectonic offset of late Pleistocene deposits. Paleoseismological analyses are in progress in order to distinguish potential coseismic movement from fault creep during the observed recent displacement

Anatomy and kinematic evolution of an ancient passive margin involved into an orogenic wedge (Western Southern Alps, Varese area, Italy and Switzerland)

We make use of own geological mapping, interpretations of seismic reflection profiles and deep geophysical data to build a lithospheric-scale cross-section across the European Western Southern Alps (Varese area) and to model a progressive restoration from the end of Mesozoic rifting to present-day. Early phases of Alpine orogeny were characterized by Europe-directed thrusting, whereas post-Oligocene shortening led to basement-involving crustal accretion accompanied by backfolding, and consistent with the kinematics of the adjoining Ivrea Zone. Wedging was favored by a significant component of reactivation of the inherited Adriatic rifted margin. Our results also suggest that, during the collisional and post-collisional tectonics, lithosphere dynamics drove diachronically the onset of tectonic phases (i.e., wedging and slab retreat), from east to west, across the Western Southern Alps

Stability Analysis of a Landslide Scarp by Means of Virtual Outcrops: The Mt. Peron Niche Area (Masiere di Vedana Rock Avalanche, Eastern Southern Alps)

We investigated the Mt. Peron niche area of the Masiere di Vedana rock avalanche (BL), one of the major mass movements that affected the Eastern Southern Alps in historical times. So far, a geomechanical characterization and a stability analysis of the niche area, where potential rockfall sources are present, are lacking. The Mt. Peron niche area is a rocky cliff almost inaccessible to field-based measurements. In order to overcome this issue, we performed a geo-structural characterization of a sector of the cliff by means of a UAV-based photogrammetric survey. From the virtual outcrop, we extracted the orientation of 159 fractures that were divided into sets based on a K-means clustering algorithm and field-checked with some measurements collected along a rappelling descent route down to the cliff. Finally, with the aim of evaluating the stability of the volume under investigation, we performed a stability analysis of three rock pillars included in our survey by means of a distinct element numerical simulation. Our results indicate that two out of the three pillars are characterized by a stable state, under the simulation assumptions, whereas the third is close to failure, and for this reason, its condition needs further investigation

The loess-paleosol sequence at Monte Netto: a record of climate change in the Upper Pleistocene of the central Po Plain, northern Italy

Purpose At the northern fringe of the Po Plain (northern Italy), several isolated hills exist, corresponding to the top of Late Quaternary anticlines. These hills were thoroughly surveyed for their soils and surficial geology, furnishing detailed archives of the palaeoenvironmental evolution of the area. A new, thick and complex loess-paleosol sequence, resting upon fluvial/fluvioglacial deposits, exposed in a quarry at the top of the Monte Netto hill was studied in detail to elucidate its significance. Materials and methods Highly deformed fluvial and fluvioglacial deposits, probably of Middle Pleistocene age, are exposed in a clay pit at Monte Netto, underneath a 2- to 4-m-thick loess-paleosol sequence. A geopedological, sedimentological and micropedological investigation of the sequence shows a distinctive difference between the B horizons forming the sequence, while luminescence and radiocarbon age determinations and the occurrence of Palaeolithic lithic assemblages elucidate the chronology of the sequence. Results and discussion The pedosedimentary sequence consists of several loess layers showing different degrees of alteration; loess deposition and weathering occurred, according to optically stimulated luminescence (OSL) and AMS-14C dating as well as archaeological materials, during the Upper Pleistocene. The lower part of the section consists of strongly weathered colluvial sediments overlying fluvial and fluvioglacial sediments. A tentative model of the exposed profiles involves the burial of the anticline, which forms the core of the hill, by loess strata since Marine Isotopic Stage (MIS) 4 and their subsequent weathering (and truncation) during subsequent interstadials. The degree of weathering of buried B horizons increases from the top of the sequence toward the bottom, suggesting a progressive decrease in the intensity of pedogenesis. Finally, the highly rubified paleosol at the top of the hill is regarded as a buried polygenetic soil or a vetusol, developed near the surface since the Middle Pleistocene. Conclusions The palaeopedological, geochronological and geoarchaeological analyses permit to define the phases and steps of development of the Monte Netto pedosedimentary sequence; the lower part of the sequence is dated to the Mid-Pleistocene, whereas loess accumulation occurred between MIS 4 and MIS 2. Moreover, analyses help to clarify the climatic and environmental context of alternating glacial and interstadial phases, during which the sediments where deposited, deformed and weathered

Quaternary capable folds and seismic hazard in Lombardia (Northern Italy): the Castenedolo structure near Brescia.

We identify evidence of late Quaternary compressive tectonics in the Northern sector of the Central Po Plain through a systematic revision of the literature, new field mapping, and a new study of seismic reflection data obtained by ENI E&P. In particular, the reinterpretation of ca. 18.000 km of seismic profiles clearly shows a belt of segmented, 10 to 20 km long, fault propagation folds, controlled by the Plio-Quaternary growth of several out-of-sequence thrusts. As an example of this active structural style, in this paper we focus on a buried fold located just south of the Castenedolo Hill, a few km SE of Brescia. Although the Castenedolo anticline has long ago been described as a young compressional structure (e.g., DESIO, 1965), no detailed structural analysis of this feature has been performed until now. We calculated the uplift rates of this fold through the analysis of its syntectonic sedimentary record as imaged by the extremely high quality ENI E&P subsurface data available in the area. The evolution of this anticline was a discontinuous process characterized by several tectonic uplift pulses (with rates of ca. 0.1 mm/yr) of different duration, separated by periods of variable extent in which no fold growth occurred. The Quaternary growth history of this anticline and the presence of faulted and folded late Pleistocene to Holocene deposits at nearby sites (Ciliverghe and Monte Netto) demonstrate that the significant seismicity of this area (e.g., the December 25, 1222, Io = IX MCS Brescia earthquake, MAGRI & MOLIN, 1986; GUIDOBONI, 1986) must be related to active compressional structures within the Brescia piedmont belt. Our regional investigations show that the structural and paleoseismic setting illustrated near Castenedolo is typical of the whole Lombardia domain of the Southern Alps. This implies that the currently accepted seismotectonic model for this region, and related seismic hazard assessment, should be thoroughly and carefully re-evaluated

10B(n,α)7Li and 10B(n,α1γ)7Li cross section data up to 3 MeV incident neutron energy

The 10 B(n,α) reaction cross-section is a well-established neutron cross-section standard for incident neutron energies up to 1 MeV. However, above this energy limit there are only scarce direct (n,α) measurements available and these few experimental data are showing large inconsistencies with each other. These discrepancies are reflected in the evaluated data libraries: ENDF/B-VII.1, JEFF-3.1.2 and JENDL-4.0 are in excellent agreement up to 100 keV incident neutrons, whereas the 10 B(n,α) data in the different libraries show large differences in the MeV region. To address these inconsistencies, we have measured the cross section of the two branches of the 10 B(n,α) reaction for incident neutron energies up to 3 MeV. We present here the 10 B(n,α) and the 10 B(n,α1 γ) reactions cross section data, their branching ratio and the total 10 B(n,α) reaction cross section. The measurements were conducted with a dedicated Frisch-grid ionization chamber installed at the GELINA pulsed neutron source of the EC-JRC. We compare our results with existing experimental data and evaluations

The liquefaction features in the area of the May-June 2012 Emilia seismic sequence: An investigation approach coupling Electric Resistivity Tomography (ERT) with coring

In order to geometrically characterize the liquefaction features observed in the epicentral sector of the 2012 Emilia seismic sequence and to evaluate the potential for recording palaeoseismic features of the area, we performed two electric resistivity tomographic sections and 4 shallow corings, coupled with 14C datings and archaeological age estimates in selected sites. Preliminary results show that there is a good agreement between ERT sections and core-logs; moreover a major role in determining the scalar relationships of the liquefaction features is played by the local geomorphological and topographic setting. The high sedimentation rates obtained through core datings (4 – 20 mm/yr) suggest that the described methodological approach can cover time windows of only a few centuries, thus hardly encompassing, in this tectonic setting, a significant period for paleoseismological purposes.Published206-2092T. Deformazione crostale attivaN/A or not JC

Surface Faulting and Ground Deformation: Considerations on Their Lower Detectable Limit and on FDHA for Nuclear Installations

We performed a review of a representative data set on coseismic surface deformation, derived from both interferometric synthetic aperture radar imaging and from a traditional field survey of surface faulting. This analysis indicates a minimum threshold value of Mw 5.4\u20135.5 for earthquake-induced ground deformation and faulting, with an inherently lower limit of detection that makes it hard to recognize surface deformation caused by Mw < 4.5\u20135.0 events. Significant exceptions are represented by shallow (i.e., less than circa 5 km) events that occur in volcano-tectonic settings, where surface deformation and dislocation are also clearly detectable for Mw circa 4.0. Furthermore, a statistically significant regression between the areal extent of surface deformation and maximum slip at surface is proposed. This correlation is discussed in relation to fault displacement hazard analysis for nuclear power plants. In particular, the deformation area is used to find a potential solution for the second and third criterion for defining a capable fault