Durand Virginie auteur aut IRD Mangeney A. auteur aut IRD Bernard P. auteur aut IRD Jia X. P. auteur aut IRD Bonilla F. auteur aut IRD Satriano C. auteur aut IRD Saurel J. M. auteur aut IRD Aissaoui E. auteur aut IRD Peltier A. auteur aut IRD Ferrazzini V. auteur aut IRD Kowalski P. auteur aut IRD Lauret F. auteur aut IRD Brunet C. auteur aut IRD Hibert C. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Quantifying the effect of external forcings like seismicity or rain on slope destabilization is a long-standing and challenging issue. To investigate the respective roles of these forcings, we analyze an unprecedented 10-year long catalog of rockfalls occurring in the crater of the Piton de la Fournaise volcano (La Reunion Island), using statistical tools originally developed for earthquakes. Our analysis reveals the predominant effect of low amplitude repetitive seismicity in the triggering of rockfalls located at a few kilometers from the source, due to progressive damaging of the slope. Moreover, we show that the efficiency and time-delay of this dynamic triggering is controlled by the stability state of the slope, i.e. its closeness to the failure, as observed with lab-experiments on metastable granular slopes. Our results show the need to account for long-term swarm-type seismic activity that can affect the stability of geological structures like slopes and faults, but also buildings. Long-term swarm-type seismic activity combined with rainfall can cause instability of volcanic structures like flanks and crater walls, according to statistical analyses of 10 years of observations at the Piton de la Fournaise volcano and lab experiments specialized REUNION 064 066 020 4 1 383 [13 ] 2023 https://www.documentation.ird.fr/hor/fdi:010088679 10.1038/s43247-023-00996-y [F B010088679] https://www.documentation.ird.fr/hor/fdi:010088679 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2024-01/010088679.pdf IRD - Base Horizon / Pleins textes 2024-01-12 2025-02-24 fdi:010088679 fre