%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture non répertoriées par l'AERES
%A Hall, M.L.
%A Robin, Claude
%A Beate, B.
%A Mothes, P.
%A Monzier, Michel
%T Tungurahua volcano, Ecuador : structure, eruptive history and hazards
%D 1999
%L fdi:010019676
%G ENG
%J Journal of Volcanology and Geothermal Research
%@ 0377-0273
%K VOLCAN ; STRUCTURE ; HISTOIRE ; HOLOCENE ; RISQUE NATUREL ; ANDESITE ; MAGMATISME ; ETUDE REGIONALE
%K EQUATEUR
%K TUNGURAHUA VOLCANO
%P 1-21
%R 10.1016/S0377-0273(99)00047-5
%U https://www.documentation.ird.fr/hor/fdi:010019676
%> https://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_7/b_fdi_51-52/010019676.pdf
%V 91
%W Horizon (IRD)
%X Tungurahua, one of Ecuador's most active volcanoes, is made up of three volcanic edifices. Tungurahua 1 was a 14-km-wide andesitic stratocone which experienced at least one sector collapse followed by the extrusion of a dacite lava series. Tungurahua 2, mainly composed of acid andesite lava flows younger than 14,000 years BP, was partly destroyed by the last collapse event, 2955 plus or minus 90 years ago, which left a large amphitheater and produced an approximately 8-km3 debris deposit. The avalanche collided with the high ridge immediately to the west of the cone and was diverted to the northwest and southwest for approximately 15 km. A larger lahar formed during this event, which was followed in turn by dacite extrusion. Southwestward, the damming of the Chambo valley by the avalanche deposit resulted in an approximately 10-km-long lake, which was subsequently breached, generating another catastrophic debris flow. The eruptive activity of the present volcano (Tungurahua 3) has rebuilt the cone to about 50% of its pre-collapse size by the emission of approximately 3 km3 of volcanic products. Two periods of construction are recognized in Tungurahua's 3 history. From approximately 2300 to approximately 1400 years BP, high rates of lava extrusion and pyroclastic flows occurred. During this period, the magma composition did not evolve significantly, remaining essentially basic andesite. During the last appromatively 1300 years, eruptive episodes take place roughly once per century and generally begin with lapilli fall and pyroclastic flow activity of varied composition (andesite + dacite), and end with more basic andesite lava flows or crater plugs. This pattern is observed in the three historic eruptions of 1773, 1886 and 1916-1918... (Résumé d'auteur)
%$ 064PETRO