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| Titel |
Survey and assessment of post volcanic activities of a young caldera lake, Lake Cuicocha, Ecuador |
| VerfasserIn |
G. Gunkel, C. Beulker, B. Grupe, F. Viteri |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 9, no. 3 ; Nr. 9, no. 3 (2009-05-08), S.699-712 |
| Datensatznummer |
250006779
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| Publikation (Nr.) |
 copernicus.org/nhess-9-699-2009.pdf |
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| Zusammenfassung |
| Cuicocha is a young volcano adjacent to the inactive Pleistocene Cotacachi volcano complex, located in the western cordilleras of
the Ecuadorian Andes. A series of eruptions with intensive ash emission and
collapse of the caldera occurred around 4500–3000 y BP. A crater 3.2 km
in diameter and a maximum depth of 450 m was formed. Further eruptions of
the volcano occurred 1300 y BP and formed four smaller domes within the
caldera. Over the last few hundred years, a caldera lake has developed, with
a maximum depth of 148 m. The lake water is characterized by sodium
carbonate with elevated concentrations of manganese, calcium and chloride.
Nowadays, an emission of gases, mainly CO2, and an input of warm spring
water occur in Lake Cuicocha. The zone of high activity is in the western
basin of the lake at a depth of 78 m, and continuous gas emissions with
sediment resuspension were observed using sonar. In the hypolimnion of the
lake, CO2 accumulation occurs up to 0.2% saturation, but the risk
of a limnic eruption can be excluded at present. The lake possesses
monomictic stratification behaviour, and during overturn an intensive gas
exchange with the atmosphere occurs. Investigations concerning the
sedimentation processes of the lake suggest only a thin sediment layer of up
to 10–20 cm in the deeper lake basin; in the western bay, in the area of
gas emissions, the lake bottom is partly depleted of sediment in the form of
holes, and no lake colmation exists. Decreases in the lake water level of
about 30 cm y−1 indicate a percolation of water into fractures and
fissures of the volcano, triggered by a nearby earthquake in 1987. |
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