Sedimentology and Structure of the Lake Palcacocha Laterofrontal Moraine Complex in the Cordillera Blanca, Peru

The contemporary retreat of tropical glaciers in the Cordillera Blanca mountain range of Peru has resulted in the widespread formation of morainedammed glacial lakes. As continued glacial melt causes these lakes to grow in size, they pose the risk of unleashing glacial lake outburst floods (GLOFs), mass-wasting events that involve rapid lake drainage facilitated by a breach in the moraine dam. In 1941, a breach in the moraine dam at Lake Palcacocha produced a GLOF that killed close to 2000 people in the city of Huaraz. Current hazard assessment criteria for GLOF occurrence do not fully reflect the role of internal moraine structure in GLOF mitigation. Field observations of the sedimentology and structure of the Lake Palcacocha moraine have allowed a sequence of events for the genesis and evolution of the moraine to be proposed. The depositional conditions under which the Lake Palcacocha moraine developed gave rise to specific sedimentological structures within the moraine that could play a role in determining its resistance to failure. A thorough understanding of the processes governing moraine formation in the Cordillera Blanca is critical for modelling the development of both past and future moraines. These models can be applied to better understand the  formation and stability of moraine dammed glacial  lakes.