Hazards Overview
Glaciers are bodies of ice that move. They shape the landscapes by carving out areas where they flow and by leaving moraines (piles of rocks carried by the glaciers) at both the edge of the ice and below it. Moving mountain glaciers create unstable landscapes where ice and rock falls are common, sometimes triggering avalanches or floods.
Given that millions of people in mountain ranges worldwide live in valleys below glaciers, there is a risk of glacier disasters in many countries. Glacier hazards have become more acute with recent global climate change and as populations in glacier watersheds increase.
The most deadly glacier disaster was the 1970 glacier avalanche from Mount Huascaran in Peru's Cordillera Blanca mountains, which killed 15,000 people.
Glacial Lake Palcacocha, Cordillera Blanca, Peru. This lake generated a deadly glacial lake outburst flood in 1941 that destroyed part of the city of Huaraz and killed 5,000 people. Note the two security dams in the foreground of the photograph. Photo by Mark Carey (2003).
Glacial lake outburst floods (GLOFs) have also caused many deaths and much destruction. As the climate warms, glaciers generally shrink. In many world regions, the retreat of glacier tongues creates unstable moraine-dammed lakes. These lakes have formed in the newly-created basins between moraines and retreating glacier tongues. Terminal moraines act as dams for these lakes, but as the lakes swell from rising water levels and the retreating glacier, the moraine dam can weaken. Moraine dams that become too weak may crumble under too much pressure from the swelling lake, creating a glacial lake outburst flood. Alternatively, and more commonly, glacial ice from the retreating glacier can crash into lakes, generating giant waves that erode weak moraine dams in a matter of minutes--thereby triggering GLOFs. These glacial lake disasters have been more frequent (and increasingly so) since end of the Little Ice Age in the late 1800s.
Advancing glaciers can also be hazardous. In the European Alps, advancing glaciers during the Little Ice Age formed ice dams across many valley floors. When too much water was stored behind the ice dam, lakes burst and killed hundreds of people.
To prevent glacial lake outburst floods, engineers have drained and dammed lakes worldwide, especially in the Peruvian Andes but also globally. Given widespread glacial lake instability and the many vulnerable populations today, it is important to distribute information about glacier hazards internationally.
The goal of this website is to exchange ideas about these glacier hazards worldwide, providing both bibliography and resources to help analyze and prevent glacier disasters in the future. For more technical information or to find researchers conducting specialized research on glacier hazards, follow the links provided.
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