Empirical rainfall thresholds for the triggering of landslides in the NW of the Iberian Peninsula: a state of the art

Abstract

In this study, we provide a comprehensive review focused on the NW of the Iberian Peninsula identifying a great amount of research works, including 85 empirical rainfall thresholds for the triggering of landslides, some unpublished to date. While the compiled works provide valuable descriptive insights, the thresholds currently have limited predictive capability. The variety of data and approaches used by different authors complicates the comparison of the results and hinders the development of a global understanding of the study area. However, the statistical comparison of four critical accumulated precipitation-duration datasets for the triggering of landslide events from Gipuzkoa, Cantabria, and Asturias in Spain and the N of Portugal highlights a notable similarity in the critical conditions for rainfall-triggered landslides with durations in the range of 3-12 days. Despite the variety of statistical approaches applied, the unexpected similarity aligns with the homogeneous climatic and orographic characteristics across NW Iberia.