Hidalgo S. auteur aut IRD Monzier Michel auteur aut IRD Almeida E. auteur aut IRD Chazot G. auteur aut IRD Eissen Jean-Philippe auteur aut IRD van der Plicht J. auteur aut IRD Hall M. L. auteur aut IRD text journalArticle eng text/pdf born digital access The Atacazo-Ninahuilca Volcanic Complex (ANVC) is located in the Western Cordillera of Ecuador, 10 km southwest of Quito. At least six periods of Pleistocene to Holocene activity (N1 to N6) have been preserved in the geologic record as tephra fallouts and pyroclastic flow deposits. New field data, including petrographic and whole-rock geochemical analyses of over forty soil and tephra sections, 100 pumice and lithic samples, and 10 new C-14 ages allow us to constrain: (1) the tephra fall isopachs and detailed characteristics of the last two events (N5-N6) including volume estimates of the tephra and pyroclastic flow deposits and the corresponding volcanic explosivity index (VEI); (2) the petrographical and geochemical correlations between domes, tephras, and pyroclastic flow deposits; and, (3) the timing of the last 4 eruptive events and a period of quiescence that endured a few thousand years (1000-4000). The last two eruptive events (N5 and N6) took place at around 4400 +/- 35 yr BP and 2270 +/- 15 yr BP, producing huge plinian and pyroclastic flow deposits. Taking into account the widely spread deposits of these VEI 5 eruptions, the present population of about 70000 people, and the current infrastructure; the development of mitigation plans and deployment of monitoring systems at ANVC is highly recommended. specialized Atacazo-ninahuilca Ecuador Holocene Stratigraphy Geochronology Radiocarbon dating Volcanic hazards 064 176 1 Special Issue 16-26 2008 0377-0273 https://www.documentation.ird.fr/hor/fdi:010044104 10.1016/j.jvolgeores.2008.05.017 0377-0273 [F A010072643] https://www.documentation.ird.fr/hor/fdi:010044104 https://www.documentation.ird.fr/intranet/publi/2008/12/010044104.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2009-01-09 2018-08-07 fdi:010044104 fre