Medieval demise of a Himalayan giant summit induced by mega-landslide

• Published in: Nature
• Main Authors: Lavé, Jérôme, Guérin, Cyrielle, Valla, Pierre, Guillou, Valery, Rigaudier, Thomas, Benedetti, Lucilla, France-Lanord, Christian, Gajurel, Ananta Prasad, Morin, Guillaume, Dumoulin, Jean Pascal, Moreau, Christophe, Galy, Valier
• Other Authors: Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut des Sciences de la Terre (ISTerre), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Tribhuvan University, Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Laboratoire de mesure du carbone 14 (LMC14 - UMS 2572), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Ministère de la Culture et de la Communication (MCC)-Centre National de la Recherche Scientifique (CNRS), Woods Hole Oceanographic Institution (WHOI), Projet Syster-INSU, CNRS, ANR-18-MPGA-0006,MAGICLIM,Climat de montagne, glaciers et dynamique du paysage(2018), ANR-09-BLAN-0221,Calimero,Influence du Climat sur les paysages et l'érosion(2009)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: [SDU]Sciences of the Universe [physics]; permafrost
• Online Access: https://hal.science/hal-04157846; https://hal.science/hal-04157846/document; https://hal.science/hal-04157846/file/Lav%C3%A9-et-al_Annapurna_Landslide_Draft_Nature.pdf; https://doi.org/10.1038/s41586-023-06040-5

International audience Despite numerous studies on Himalayan erosion, it is not known how the very high Himalayan peaks erode. Although valley floors are efficiently eroded by glaciers, the intensity of periglacial processes, which erode the headwalls extending from glacial cirques to crest lines, seems to decrease sharply with altitude. This contrast suggests that erosion is muted and much lower than regional rock uplift rates for the highest Himalayan peaks, raising questions about their long-term evolution. Here we report geological evidence for a giant rockslide that occurred around 1190 ad in the Annapurna massif (central Nepal), involving a total rock volume of about 23 km$^3$. This event collapsed a palaeo-summit, probably culminating above 8,000 m in altitude. Our data suggest that a mode of high-altitude erosion could be mega-rockslides, leading to the sudden reduction of ridge-crest elevation by several hundred metres and ultimately preventing the disproportionate growth of the Himalayan peaks. This erosion mode, associated with steep slopes and high relief, arises from a greater mechanical strength of the peak substratum, probably because of the presence of permafrost at high altitude. Giant rockslides also have implications for landscape evolution and natural hazards: the massive supply of finely crushed sediments can fill valleys more than 150 km farther downstream and overwhelm the sediment load in Himalayan rivers for a century or more.