The biggest landslide event in Brazil: preliminary analysis of the Rio Grande do Sul mega disaster in May 2024

This paper provides the preliminary results of an inventory of the landslides triggered by the late April and early May 2024 storm, in which the state of Rio Grande do Sul in Brazil experienced the most severe meteorological event in its history. This unprecedented precipitation event caused widespread floods and landslides, impacting 96% of the state's municipalities, and affecting approximately 2.4 million people. This study provides a scientific analysis of the event's scale, spatial distribution and the associated topographic, environmental and infrastructural conditions.

The results of the analysis reveal that the event triggered 15,376 landslides across approximately 18,000 km², with 16,862 landslide initiation points. Thus, the Rio Grande do Sul event represents the largest landslide occurrence ever recorded in Brazil, measured by the metric of quantity. This document has been utilised in geological risk assessment, public policy and resource allocation, infrastructure reconstruction planning, urban risk and planning revision, and scientific communication - thus highlighting the need for a comprehensive landslide inventory in the wake of such as disastrous event.