Late Holocene eruptive activity at Nevado Cayambe Volcano, Ecuador |
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| Authors: | P Samaniego M Monzier C Robin M L Hall |
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| Institution: | (1) Instituto Geofìsico, Escuela Politécnica Nacional, Apartado Postal 17-01-2759, Quito, Ecuador, EC;(2) ORSTOM, Apartado Postal 17-11-6596, Quito, Ecuador, EC |
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| Abstract: | Four Late Holocene pyroclastic units composed of block and ash flows, surges, ashfalls of silicic andesite and dacite composition,
and associated lahar deposits represent the recent products emitted by domes on the upper part of Nevado Cayambe, a large
ice-capped volcano 60 km northeast of Quito. These units are correlated stratigraphically with fallout deposits (ash and lapilli)
exposed in a peat bog. Based on 14C dating of the peat and charcoal, the following ages were obtained: ∼910 years BP for the oldest unit, 680–650 years BP for
the second, and 400–360 years BP for the two youngest units. Moreover, the detailed tephrochronology observed in the peat
bog and in other sections implies at least 21 volcanic events during the last 4000 years, comprising three principal eruptive
phases of activity that are ∼300, 800, and 900 years in duration and separated by repose intervals of 600–1000 years. The
last phase, to which the four pyroclastic units belong, has probably not ended, as suggested by an eruption in 1785–1786.
Thus, Cayambe, previously thought to have been dormant for a long time, should be considered active and potentially dangerous
to the nearby population of the Interandean Valley.
Received: 5 July 1997 / Accepted: 21 October 1997 |
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| Keywords: | Tephrochronology Pyroclastic flow Holocene Cayambe Volcano Ecuador |
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