Determination and analysis of the rainfall triggering landslides in the ITALICA catalogue&#160;
Authors: Peruccacci Silvia , Gariano Stefano Luigi , Melillo Massimo , Guzzetti Fausto , Brunetti Maria Teresa 
Published: March 2024

The wide physiographic variability and the abundance of rainfall and landslide data make Italy an appropriate site to study variations in the rainfall conditions responsible for triggering landslides.For more than two decades, the Research Institute for Geo-Hydrological Protection of the Italian National Research Council (CNR-IRPI) has been carrying out a specific research activity aimed at collecting information on rainfall-induced landslides in Italy. The information comes mainly from chronicle sources (newspapers in print or electronic format, websites, etc.) and institutional sources (reports on interventions carried out by the Fire Brigade and other institutional entities following reports of weather-induced landslides). The information collected has been used to compile the ITAlian rainfall-induced LandslIdes CAtalogue (ITALICA), freely accessible at https://zenodo.org/records/8009366. A description of the main features of the catalogue and the procedures adopted to fill it out can be found at https://essd.copernicus.org/articles/15/2863/2023/.ITALICA, which is being continuously updated, to date contains data on more than 6300 rainfall-induced landslides that occurred in Italy during the period 1996-2021. The peculiarity and specificity of the catalogue lies in the mastery and control of the landslide records, which have very high levels of spatial and temporal accuracy. In particular, for more than one third of the catalogue, landslides are spatially and temporally localized with an uncertainty of less than one km2 and one hour, respectively. The availability of accurate and up-to-date information on the geographic location and time of onset of landslides is essential for improving the predictive ability of landslides. Different subsets of the catalogue have been already used to calculate national and regional rainfall thresholds implemented in early warning systems in Italy.The first published version of ITALICA did not contain information on the rainfall conditions associated with the landslides. In the new release, presented here, we add the cumulate rainfall, rainfall duration and mean rainfall intensity values of the rainfall conditions responsible for the failures listed in the catalogue. The rainfall conditions are reconstructed by means of the CTRL-T automatic tool (https://zenodo.org/records/4533719) and using hourly rainfall measurements from more than 3000 rain gauges distributed over the Italian territory. Rainfall records are provided by the Italian National Department for Civil Protection. The spatial and temporal features of the reconstructed landslide-triggering rainfall conditions are analysed in depth.Given the rising demand for high-quality data to be used in comprehensive analyses and data-driven models, this dataset might be very useful for assessing the rainfall triggering conditions of landslides in Italy, either by empirical or physically based models. In particular, we expect our results to have an impact on the definition of new rainfall thresholds to be implemented in landslide early warning systems at regional and national scales.&#160;Work financially supported by the Italian National Department for Civil Protection (Accordo di Collaborazione 2022-2024) and the PRIN-ITALERT project (PRIN2022 call, grant number: 202248MN7N, funded by NextGenerationEU).