Chmiel M. auteur aut IRD Godano M. auteur aut IRD Piantini M. auteur aut IRD Brigode P. auteur aut IRD Gimbert F. auteur aut IRD Bakker M. auteur aut IRD Courboulex F. auteur aut IRD Ampuero Jean-Paul auteur aut IRD Rivet D. auteur aut IRD Sladen A. auteur aut IRD Ambrois D. auteur aut IRD Chapuis M. auteur aut IRD text journalArticle eng text/pdf reformatted digital access On 2 October 2020, the Maritime Alps in southern France were struck by the devastating Storm Alex, which caused locally more than 600 mm of rain in less than 24 h. The extreme rainfall and flooding destroyed regional rain and stream gauges. That hinders our understanding of the spatial and temporal dynamics of rainfall-runoff processes during the storm. Here, we show that seismological observations from permanent seismic stations constrain these processes at a catchment scale. The analysis of seismic power, peak frequency, and the back azimuth provides us with the timing and velocity of the propagation of flash-flood waves associated with bedload-dominated phases of the flood on the Vesubie River. Moreover, the combined short-term average to long-term average ratio and template-matching earthquake detection reveal that 114 local earthquakes between local magnitude M-L = -0.5 and M-L = 2 were triggered by the hydrological loading and/or the resulting in situ underground pore pressure increase. This study shows the impact of Storm Alex on the Earth's surface and deep-layer processes and paves the way for future works that can reveal further details of these processes. specialized FRANCE 066 062 021 22 5 1541-1558 2022 1561-8633 https://www.documentation.ird.fr/hor/fdi:010084775 10.5194/nhess-22-1541-2022 1561-8633 [F B010084775] https://www.documentation.ird.fr/hor/fdi:010084775 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2022-06/010084775.pdf IRD - Base Horizon / Pleins textes 2022-06-03 2025-02-24 fdi:010084775 fre