11 páginas.

La fuerte orografía del territorio nacional plantada por la presencia de la Cordillera de los Andes, con alturas superiores a los 6,000 m. hace que a lo largo del país se tenga áreas glaciares, cuya evolución presenta importantes interrogantes de tipo técnico, ya sea por su rápido dinamismo (la parte más ecuatorial) que permite una inicial formación de lenguas glaciares y lagunas, cuyo rompimiento han causado ya muchas catástrofes naturales. Por otra parte, estas reservas de agua al estado sólido requieren una evaluación con fines de un aprovechamiento racional. En base a estos objetivos el Programa de Glaciología y Seguridad de lagunas del INGEOMIN - Huaraz viene trabajando con preferente atención en las áreas glaciares del Norte del país, llegando a tenerse· un conocimiento integral de las mismas, plasmado en un inventario de Lagunas y Glaciares con mapas a escala l: 10...

We explain how preliminary results concerning the internal constitution of the big push moraine at Safuna were obtained in 1967. Cross-sections which were obtained later through electrical and seismic exploration and arduous borings are given. Under the lake Safuna Alta there exists a layer of dead ice which is probably a remnant from an old glacier advance and over which the active glacier slides, but this dead ice does not extend into the push moraine. Since 1950 Safuna Alta has formed, the glacier tongue has lowered by 0.8 m per year on average, and the big push moraine has moved and settled. The annual balance on the glacier tongue was measured in 1968. It increases by 3.9 m of ice per 100 m in altitude. The discharge of ice near the lake and the annual balance further up-valley allow an estimate of the mean annual balance in the accumulation zone (between 4850 and 6020 m) at 2.30 m ...

The retreat of glaciers since 1927 in Cordillera Blanca has produced dangerous lakes on the front of many glaciers. All the known data, most of them unpublished, are reviewed. The known aluviones are listed, and those of Chavin, Quebrada Los Cedros and Artesoncocha described in full. In these three cases a breach in the front mo ra ine came from big ice falls into the lake. The protective d evices made on the outlets are described, as well as the effects of the big earthquake on 31 May 1970. In the case of Laguna Parón, which keeps its level thanks to infiltrations, the flu ctuations of the discharge of the springs as related to the level of the lake from 1955 to 1969 are reported. The projects for lowering the level of Laguna Parón and for emptying Safuna Alta are described. The latter partially emptied in fact by piping after the earthquake, allowing a final solution.