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Landslides are among the most frequent secondary effects related to seismic events. The prediction of the expected displacements of landslides activated by seismic shaking (1st-time failures and reactivated landslides) is therefore a substantial feature for the hazard assessment in high seismicity regions. Several databases collecting geological and geometrical information on worldwide landslides events are available in literature. This study presents the result of statistical analyses on morphometric, topographic and geotechnical parameters extracted from existing landslide databases (Domej et al., 2020; Martino et al., 2019; Tanyas et al., 2019). The aim is to define a procedure to generate 2D step-like-slope landslide models representative of the most common landslides in terms of failure mechanism (divided into two main categories: purely rotational and translational landslides), volume, and geotechnical properties. Rock falls and toppling, flow-like landslides and deep-seated landslides were excluded from the initial dataset, because they are associated with peculiar physical processes during the failure and the propagation. The performed statistical analysis allowed to identify the most frequent values of depth/length ratios, volume and slope angle, from which other geometrical measurements were analytically derived. In addition, various landslide locations along the slope were considered to cover most of the real cases. This resulted in 36 different landslides/slopes shapes. Landslides dynamic/geotechnical parameters (shear wave velocity, density, strength) were selected to be consistent with those inferred for rocks, cohesive soils and granular soils by statistical analysis. The representativeness of the inferred models is assessed by comparing the theoretical geometries with the real ones detected in the Campotosto Basin (Central Apennines, Italy), a high seismicity area very close to the Amatrice village, which was strongly hit by the recent 2016-2017 (M 6.5) Central Italy seismic sequence as well as by the 2009 (M 5.9) L’Aquila earthquake. The simplified landslide models represent the first part of a major study on the prediction of seismically induced landslide displacements. The aim is to improve the existing Newmark’s approach–based PARSIFAL (Probabilistic Approach to pRovide Scenarios of earthquake-Induced slope FAiLures) method (Martino et al., 2019) to assess the earthquake-induced displacements at a regional scale, by introducing corrective factors derived from parametric dynamic numerical simulations on the simplified geometries; such factors should incorporate some aspects of the complex seismic waves/landslides slopes interaction. Such a procedure will allow to overcome the Newmark’s method limitations and to extend the advantages of the numerical analyses, the use of which is generally limited to studies at slope scale, over larger areas.

Rock mass damaging has become a topic of great interest in the engineering-geology research community during the last decades as it can significantly influence slopes stability. In this sense, the study of mechanics and dynamics of jointed rock masses represents a challenge because it will allow to better understand how external continuous and transient stressors can influence the short- to long-term stability controlling their pre-failure behavior. Consequently, the detection of permanent changes in physical and mechanical parameters, due to periodic or transient stressors, is an important target to mitigate the related geological risk as it can potentially lead rock masses to failure, especially when infrastructures and natural or cultural heritages are exposed elements. In this framework, the Acuto field laboratory (Central Italy) has been designed and implemented in 2016 within an abandoned quarry by employing an integrated geotechnical and geophysical monitoring system, with the aim of investigating how natural and anthropic conditioning factors could lead fractured rock masses to failure. The integrated monitoring system, which is installed on a potentially unstable 20-m3 jointed rock block, is composed of several strain devices (i.e., strain gauges -SG- and jointmeters -JM-), one fully equipped weather station, one rock thermometer, eight high-sensitivity microseismic uniaxial accelerometers and optical and InfraRed Thermal cameras. The acquisition of long-term monitoring time-series, coupling multimethodological approaches, allowed to establish cause-to-effect relationships among different environmental stressors and induced strain effects, highlighting the continuous action of thermal stresses on rock mass deformations both at the daily and seasonal timescales. In fact, while the analysis of thermal and strain monitoring data allowed to characterize the cyclic contraction and relaxation response of major rock fractures and microcracks to temperature fluctuations, the microseismic monitoring array was able to detect during thermal transient (i.e., freezing conditions) the occurrence of microseismic emissions potentially related to the genesis or progressive growth of pre-existing cracks.Starting from 2018, experimental activities at the Acuto field lab are supported by the “Dipartimento di Eccellenza” project of the Italian Ministry of Education Universities and Research funds attributed to the Department of Earth Sciences of the University of Rome “Sapienza”. In this framework, the Acuto filed laboratory will undergo a structural upgrade that will be aimed at the investigation of two new sectors of the abandoned quarry. These new sectors will be instrumented with innovative thermal profiles probe, fiber Brag grating sensors and traditional SG and JM for detailed stress-strain monitoring, acoustic emission sensors and high-frequency and low-frequency geophones for ambient seismic noise monitoring and microseismic events detection as well as accelerometers for evaluating the rock mass response in the case of seismic shaking. The main goal of such an improvement will be both technical and methodological, and will shed light on the application of integrated geophysical and geotechnical monitoring approaches in investigating the multiscale rock mass damaging process as well as the detection of rock mass failure precursors by using non-conventional combinations and configurations of geotechnical and broad-band geophysical devices.

The morphological evolution of landslide slopes is generally controlled by the combination of weathering, tectonics, gravity and river erosion. Among them, seismic shaking plays a fundamental role in landslide activity and mobility in high seismicity regions. It can result in important modifications of landslide geometry and consequently, of its response to external loadings. In particular, morphological changes in landslide slope can imply changes in the interactions between seismic waves and landslide mass, which could theoretically modify the hazard related to the earthquake-induced effects. This study aims at pointing out the effects of slope morpho-evolution on the long-term modification of earthquake-induced landslide dynamics, which is here quantified in terms of expected seismically induced displacements, considering unaltered seismic hazard conditions. The Albuñuelas landslide was selected, located in Andalusia (South Spain) which is one of the most seismic regions of Spain. This landslide is a large roto-translational process whose last earthquake-induced reactivation occurred during the 1884 Andalusia Earthquake (Mw 6.5), causing relevant damages to the Albuñuelas village. Data available from field surveys and geophysical investigations, allowed to derive the current engineering-geological model of the landslide slope. According to the available geological and geomorphological data, the slope shape was back-deformed to reproduce the landslide geomorphological evolution sequence over time, until its first-time failure. The reconstructed sequence is consistent with a geomorphological evolution mainly driven by the combination of earthquake-induced re-activations and low rates of deformation caused by the intense incision of the Albuñuelas River, responsible for the valley deepening. 2D-dynamic stress-strain numerical simulations were performed on several stages of such sequence applying 17 equivalent signals derived following the LEMA_DES (Levelled-Energy Mutifrequential Analysis for Deriving Equivalent Signals) approach with an Arias Intensity of 0.1 m/s, according to the Andalusia regional seismic hazard. The outputs were expressed in terms of seismically induced displacements vs. characteristic periods diagrams, in order to highlight the role of signal frequency content as well as the effect of the landslide 2D-geometry (Tl) and thickness (Ts) on the resulting displacements. Since the morpho-evolution resulted in a progressive increasing of the landslide mass length and its dislodgment into several blocks since the first-time failure, the landslide mobility was analysed over time at each single-block scale. The comparison revealed a not neglectable modification of the Albuñuelas landslide susceptibility to the local seismic hazard over time, highlighting the necessity to understand the mechanisms driving the natural system evolution to provide more reliable earthquake-induced hazard scenarios.

For many geotechnical purposes, the proper estimation of shapes and dimensions of landslide rupture zones is of significant importance. Very often this exact delineation is difficult due to the lack of information on rupture zone extents in 3D. Based on a global landslide inventory, this study presents a refined statistical analysis correlating dimension-related and shape-related parameters characterizing a rupture zone in 3D to its volume. Dimension-parameters are approximated by linear regressions increasing with greater volumes, whereas shape-related parameters appear stable throughout the entire range of volumes. Revealing themselves as very stable, these correlations can be used, hence, to extrapolate from a distinct parameter to the volume of a landslide rupture zone. In a second stage, ratios of dimension-related parameters are correlated with rupture zone volumes. Also, this type of correlation delivers very stable results showing that ratios are constant throughout the entire range of volumes. Making use of this ratio consistency, it is possible to deduce one of the two parameters when the other one is given. This latter aspect seems to be promising for remote sensing surveys when initial rupture areas or rupture volumes should be delineated.