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Earth flows are complex geological processes that, when interacting with linear infrastructures, have the potential to cause significant damage. Consequently, conducting comprehensive investigations and continuous monitoring are becoming paramount in designing effective mitigation measures and ensuring sustainable risk management practices. The use of digital image correlation (DIC) algorithms for the displacement monitoring of earth flows is a relatively new and growing field with a limited number of dedicated works in the literature. Within this framework, the present paper contributes by evaluating DIC techniques at several earth flow sites. These assessments were founded upon data obtained from both low-cost and multi-platform sensors, used to assess the displacement field, pinpointing the most active sectors, and gauging their rates of movement during different kinematic phases. In this regard, the highest localized movement velocities reached in the Pietrafitta (0.01 m/day) and Grillo (0.63 m/day) earth flows experience different ongoing kinematic processes. The versatility of these techniques is notable, manifesting in the ease of installation, cost-effectiveness, and adaptability to various platforms. The proven reliability in terms of maximum accuracy (1 pixel) and sensitivity (0.05 m) lays the foundation for the extensive use of the presented techniques. The amalgamation of these attributes positions DIC techniques as competitive, adaptable, and readily deployable tools in earth flow studies. [ABSTRACT FROM AUTHOR]

Earth flows are complex gravitational events characterised by a heterogeneous displacement pattern in terms of scale, style, and orientation. As a result, their monitoring, for both knowledge and emergency purposes, represents a relevant challenge in the field of engineering geology. This paper aims to assess the capabilities, peculiarities, and limitations of different remote sensing monitoring techniques through their application to the Pietrafitta earth flow (Southern Italy). The research compared and combined data collected during the main landslide reactivations by different ground-based remote sensors such as Robotic Total Station (R-TS), Terrestrial Synthetic Aperture Radar Interferometry (T-InSAR), and Terrestrial Laser Scanner (TLS), with data being derived by satellite-based Digital Image Correlation (DIC) analysis. The comparison between R-TS and T-InSAR measurements showed that, despite their different spatial and temporal resolutions, the observed deformation trends remain approximately coherent. On the other hand, DIC analysis was able to detect a kinematic process, such as the expansion of the landslide channel, which was not detected by the other techniques used. The results suggest that, when faced with complex events, the use of a single monitoring technique may not be enough to fully observe and understand the processes taking place. Therefore, the limitations of each different technique alone can be solved by a multi-sensor monitoring approach. [ABSTRACT FROM AUTHOR]

The Benevento Province (southern Italy) has been historically affected by soil erosion and ground deformation (i.e. landslides; Revellino et alii, 2019), as testified by documents and reports which describe damage scenario, social effects, surveys and measures carried out. Revellino et alii (2010) highlighted as the landslide index, defined as the ratio of areas affected by landslides over total areas, reaches up to 90%. Earth flows make up about 46% of these landslides, involving structurally complex geologic formations and often responsible for damaging human infrastructures (e.g. roads and service lines; Guerriero et alii, 2016; Maresca et alii, 2022). As a result, the province has widespread problems in management of the landslide hazard, due to the activation (and reactivation) of phenomena connected to both rainfall and seismic events. In order to reconstruct state of activity maps for the Benevento Province, a multitemporal analysis of multiplatform satellite data was carried out, with a resolution of cells of 20×20 m. In particular, PSInSAR (ERS 1&2 for the time-span 1992-2000, ENVISAT for 2002-2010, and RADARSAT for 2003-2007) and ISBAS data (Sentinel-1 for 2017-2020), were first treated by a grid-based approach to uniform the PS data and subsequently, by a multiplatform approach defining weighted average velocity (VWA) maps on the base of the extent of the area with data availability. Finally, a multiplatform activity-matrix approach allowed the definition of landslide activity maps based on a velocity threshold of ± 3 mm/y, derived by VWA maps. Specifically, velocity threshold allowed to discriminate for each cell of the analyzed area i) stable cells (velocities between ± 3 mm/y), ii) unstable cells (velocities greater than ± 3 mm/y), iii) cells with no data (unclassified). The multiplatform activity-matrix approach at provincial scale was used to identify and analyze unstable area (hotspots), currently involved in active deformation processes. Among them, the Paupisi municipality (Benevento Province) was identified as critical for the involvement of built-up areas and infrastructures in landslide deformation processes. For that reason, Paupisi area was selected as study case and a detailed analysis of the PS distribution as well as reconstruction and evaluation of deformation trend were carried out. Finally, a relation between land deformation and rainfall events was also investigated. [ABSTRACT FROM AUTHOR]

Continuous monitoring of earth flow displacement is essential for the understanding of the dynamic of the process, its ongoing evolution and designing mitigation measures. Despite its importance, it is not always applied due to its expense and the need for integration with additional sensors to monitor factors controlling movement. To overcome these problems, we developed and tested a low±cost Arduino±based wire±rail extensometer integrating a data logger, a power system and multiple digital and analog inputs. The system is equipped with a high±precision position transducer that in the test configuration offers a measuring range of 1023mm and an associated accuracy of ±1 mm, and integrates an operating temperature sensor that should allow potential thermal drift that typically affects this kind of systems to be identified and corrected. A field test, conducted at the Pietrafitta earth flow where additional monitoring systems had been installed, indicates a high reliability of the measurement and a high monitoring stability without visible thermal drift. [ABSTRACT FROM AUTHOR]

The Mount Pizzuto earth flow has been periodically active in recent decades. Early in 2006, it surged and created a dam across the Ginestra torrent. Episodic floods induced by the earth-flow dam periodically damaged a section of a local road and power and telephone service lines. This paper presents a map showing deformational structures along the flow and a geometric reconstruction of thrust faults at the earth-flow toe from 2006 to 2014. The map, produced on the basis of field observations, shows the spatial distribution of back-tilted surfaces, flank ridges and normal, thrust, and strike-slip faults. Springs, creeks, and ponds are also shown on the map. The map indicates that the earth flow is composed of five kinematic zones. Cartographic data and the spatial–temporal reconstruction of the thrusting evolution offer the basis for interpreting the (mid-term) kinematics of the flow and its controlling factors, and for assessing the influence of earth-flow movement on torrent channel capacity. [ABSTRACT FROM AUTHOR]

This study presents a new proxy for the reconstruction of the historical activity of large earth flows. A simple relationship between rainfall, temperature and groundwater levels was established using available monthly time series and subsequently utilized to develop the Landslide Hydrological Climatological (LHC) indicator to simulate the effects of hydroclimatic influence on slope stability for the Montaguto earth flow in Southern Italy. In order to identify phases of earth-flow activity, an empirical threshold was assigned. Our result indicates a different response of the earth flow to hydroclimatic stress with both ordinary and extraordinary reactivations over the historic period. Additional information suggests that earth-flow reactivations are clustered in the spring and an extraordinary earth-flow activity follows periods with a LHC below the average. A modeling result shows that the LHC is able to realistically reconstruct the long-term activity of a complex earth flow with only a few false-positives in a very long period of application. Thus, it can be considered as a tool for long-term earth-flow activity reconstruction and assessment. [ABSTRACT FROM AUTHOR]

Historical movement of the Montaguto earth flow in southern Italy has periodically destroyed residences and farmland, and damaged the Italian National Road SS90 and the Benevento-Foggia National Railway. This paper provides maps from an investigation into the evolution of the Montaguto earth flow from 1954 to 2010. We used aerial photos, topographic maps, LiDAR data, satellite images, and field observations to produce multi-temporal maps. The maps show the spatial and temporal distribution of back-tilted surfaces, flank ridges, and normal, thrust, and strike-slip faults. Springs, creeks, and ponds are also shown on the maps. The maps provide a basis for interpreting how basal and lateral boundary geometries influence earth-flow behavior and surface-water hydrology. [ABSTRACT FROM AUTHOR]

We investigated relations between slip-surface geometry and deformational structures and hydrologic features at the Montaguto earth flow in southern Italy between 1954 and 2010. We used 25 boreholes, 15 static cone-penetration tests, and 22 shallow-seismic profiles to define the geometry of basal- and lateral-slip surfaces; and 9 multitemporal maps to quantify the spatial and temporal distribution of normal faults, thrust faults, back-tilted surfaces, strike-slip faults, flank ridges, folds, ponds, and springs. We infer that the slip surface is a repeating series of steeply sloping surfaces (risers) and gently sloping surfaces (treads). Stretching of earth-flow material created normal faults at risers, and shortening of earth-flow material created thrust faults, back-tilted surfaces, and ponds at treads. Individual pairs of risers and treads formed quasi-discrete kinematic zones within the earth flow that operated in unison to transmit pulses of sediment along the length of the flow. The locations of strike-slip faults, flank ridges, and folds were not controlled by basal-slip surface topography but were instead dependent on earth-flow volume and lateral changes in the direction of the earth-flow travel path. The earth-flow travel path was strongly influenced by inactive earth-flow deposits and pre-earth-flow drainages whose positions were determined by tectonic structures. The implications of our results that may be applicable to other earth flows are that structures with strikes normal to the direction of earth-flow motion (e.g., normal faults and thrust faults) can be used as a guide to the geometry of basal-slip surfaces, but that depths to the slip surface (i.e., the thickness of an earth flow) will vary as sediment pulses are transmitted through a flow. [ABSTRACT FROM AUTHOR]

Surface mapping, GPS surveys, T-Lidar surveys, boreholes, seismic profiles, and HVSR measurements were used to study the mechanisms of sediment transport along the Mount Pizzuto earth flow in southern Italy. The earth flow has several kinematic zones, with transitional areas marked by changing structural styles, from compressional structures (thrusts) upslope to extensional structures (normal faults) downslope. We relate sediment discharge at these transitional zones to internal strain. The results suggest that during surge events, flow acceleration starts within the head and propagates downslope inducing a cascade effect between kinematic zones. During surge events, the average sediment discharge is nearly constant, and a change from sliding to flowing allows propagation of movement towards the toe. During slow movement, kinematic zones are independent and sediment discharge varies along the flow. In general, the velocity profile and the structural style are controlled by the basal slip surface. The implications are: i) sediment discharge is not constant but is a function of the earth flow activity, ii) during surge, earth flow material behaves similar to an incompressible fluid, and iii) the distribution of surface structures can provide information about the geometry of the slip surface and the velocity profile. Additionally, earth flows with a well-defined neck seem to be more likely to surge with respect to those without. [ABSTRACT FROM AUTHOR]