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Article Dans Une Revue Natural Hazards and Earth System Sciences Année : 2022

Brief communication: Seismological analysis of flood dynamics and hydrologically triggered earthquake swarms associated with Storm Alex

Maxime Godano
Françoise Courboulex
Jean Paul Ampuero
Diane Rivet
Anthony Sladen
David Ambrois

Résumé

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 Vésubie 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 ML = −0.5 and ML = 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

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Dates et versions

hal-03661182 , version 1 (06-05-2022)

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Małgorzata Chmiel, Maxime Godano, Marco Piantini, Pierre Brigode, Florent Gimbert, et al.. Brief communication: Seismological analysis of flood dynamics and hydrologically triggered earthquake swarms associated with Storm Alex. Natural Hazards and Earth System Sciences, 2022, 22 (5), pp.1541-1558. ⟨10.5194/nhess-22-1541-2022⟩. ⟨hal-03661182⟩
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