Holocene explosive activity of Hudson Volcano, southern Andes |
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| Authors: | José A Naranjo Charles R Stern |
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| Institution: | (1) Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309–0399, USA, US;(2) Servicio Nacional de Geología y Minería, Casilla 10465, Santiago, Chile, CL |
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| Abstract: | Fallout deposits in the vicinity of the southern Andean Hudson Volcano record at least 12 explosive Holocene eruptions, including
that of August 1991 which produced ≥4 km3 of pyroclastic material. Medial isopachs of compacted fallout deposits for two of the prehistoric Hudson eruptions, dated
at approximately 3600 and 6700 BP, enclose areas at least twice that of equivalent isopachs for both the 1991 Hudson and the
1932 Quizapu eruptions, the two largest in the Andes this century. However, lack of information for either the proximal or
distal tephra deposits from these two prehistoric eruptions of Hudson precludes accurate volume estimates. Andesitic pyroclastic
material produced by the 6700-BP event, including a 1 10-cm-thick layer of compacted tephra that constitutes a secondary
thickness maximum over 900 km to the south in Tierra del Fuego, was dispersed in a more southerly direction than that of the
1991 Hudson eruption. The products of the 6700-BP event consist of a large proportion of fine pumiceous ash and accretionary
lapilli, indicating a violent phreatomagmatic eruption. This eruption, which is considered to be the largest for Hudson and
possibly for any volcano in the southern Andes during the Holocene, may have created Hudson's 10-km-diameter summit caldera,
but the age of the caldera has not been dated independently.
Received: 31 January 1997 / Accepted: 29 October 1997 |
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| Keywords: | Andean volcanism Southern Andes Explosive volcanism Tephra Caldera Hudson Volcano |
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