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Landslide inventories are crucial for evaluating susceptibility, hazards, and risks, and for devising resilience strategies in mountainous regions. This importance is amplified in the context of climate change, as existing inventories might not adequately reflect changing stability conditions. In May 2023, the Emilia-Romagna region of Italy was hit by two major rainfall events, leading to widespread flooding and the triggering of thousands of landslides. Predominantly, these were shallow debris slides and debris flows, occurring on slopes previously deemed stable based on historical data with no prior landslides recorded. Our team supported the Civil Protection Agency through field surveys and mapping efforts to pinpoint and record these landslides, prioritizing areas critical to immediate public safety and focusing on thorough mapping for future recovery planning. The outcome is a detailed map of all landslides induced by these events, manually identified using high-resolution aerial photography (0.2 m pixel resolution, RGB+NIR four bands) and categorized with the help of a 3D viewer. This comprehensive landslide inventory, comprising 80997 polygons, has been made openly accessible to the scientific community. [ABSTRACT FROM AUTHOR]

The Camugnano landslide, located in the Province of Bologna, affects an area of 9.1×105 m². It is considered a complex phenomenon involving both roto-translational kinematics within the Camugnano Formation’s arenaceous flysch and translational slides that affect the degraded products of the flysch and other clay materials in the lower sector of the unstable slope. The activity of the landslide is characterized by very slow displacement rates (4 cm/year), with occasional acceleration events in the past. The most recent significant event occurred in 2014. In response, various surveys and monitoring activities were conducted, including the use of boreholes, geophysical surveys, displacement measurements through inclinometers, Ground Navigation Satellite System (GNSS), and Robotic Total Station (RTS), and groundwater monitoring through pressure transducers installed in piezometers. The aim of this note is to summarize the monitoring results and compare them with the trend of effective rainfall over multiple years. To determine effective precipitation, the Thornthwaite formulation was used, based on mean daily temperature and daily cumulative rainfall data from the Diga del Brasimone gauge station, located approximately 5 km from the landslide site. The inclinometer monitoring helped identify the sliding surfaces and obtain time series data by integrating displacements on these surfaces. GNSS campaigns conducted periodically revealed displacement rates ranging from 30 to 70 mm/year, generally decreasing progressively from 2014 to 2022. RTS monitoring indicated slow but detectable movements within the landslide. Then comparing GNSS displacements with precipitation data, it was found that displacement rates remained relatively constant regardless of variations in effective precipitation. This trend was also observed when analysing inclinometer data. The groundwater monitoring showed seasonal fluctuations, with peak levels occurring during the winter period in most piezometers. However, no long-term groundwater trend was observed. The displacement record highlights a variable sensitivity of the slope to effective rainfall with respect to the last major reactivation event. Temporary, localized accelerations are in fact recorded after 2014, gradually decreasing in magnitude in the next years. These findings suggest that mitigation strategies could by modified according to this style of activity and indicate that assumptions linking rainy or dry periods to variations in movement acceleration or deceleration may be overly simplistic. [ABSTRACT FROM AUTHOR]

During the 13 October 2014 rainstorm event that affected the Val Parma and Val Baganza area, several debris flows affected the Mt. Cervellino relief (northern Apennines, Italy), causing severe and widespread damages to check-dams, roads and other infrastructures. Such event, together with the Piacenza province event of 2015, has generated the perception of debris flows as a breaking new potential cause of widespread damages in the Emilia-Romagna. The meteorological event of October 2014, reconstructed by means of rain gauges and radar data, reached intensities as high as 80 mm/hour, which is well above any debris flow triggering thresholds presented in literature. However, data show that debris flows have occurred in any location where 30 mm/hour were exceeded. The result was the occurrence of tens of debris flows, which were triggered in zones of failure of slope debris coverage along the streams, and that remobilized and scoured debris along the track and destroyed several check dams and damaged roads that were overflown by debris. This paper is aimed to document the distribution and characteristics of the debris flow events that occurred during such event. By doing so, it also warns against this potentially destructive events that, in a changing meteorological framework, might result much more frequent and widespread than expected also in the northern Apennines. [ABSTRACT FROM AUTHOR]