Abstract

COLAVITTO, Bruno; ORTS, Darío L  and  FOLGUERA, Andrés. The historic outburst flood of the laguna Derrumbe, Cholila, Chubut: Fast glacier retreat and moraine dam failure in North Patagonian Cordillera. Rev. Asoc. Geol. Argent. [online]. 2012, vol.69, n.3, pp.457-465. ISSN 0004-4822.

The Laguna Derrumbe is a body of water located in the North Patagonian Andes, in Chubut province, Argentina. This lake is contained in a glacial cirque and dammed by the terminal moraine of the namesake glacier. Through field survey it was possible to describe this lake and an important rocky deposit downstream of it, which is interpreted as an outburst flood deposit. These deposits are generated by high-energy processes related to the failure of a natural dam, in this case a moraine dam. The study made allowed to conclude that the frontal moraine of the Derrumbe glacier suffered a partial rupture in historic times, unleashing a flash flood downstream to the lake, through the Tigre river valley in the town of Cholila. In this work the possible causes that led to the failure are discussed, concluding that the main cause was probably the fast retreat that the glacier experimented in the 50´s and early 60´s, similarly to the general glacier retreat observed in the Patagonian Andes during the last century.

Keywords : Climate change; Patagonian Andes; Mass wasting; Earthquake.

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