Serac

A serac (originally from Swiss French sérac) is a block or column of glacial ice, often formed by intersecting crevasses on a glacier. Commonly house-sized or larger, they are dangerous to mountaineers since they may topple with little warning. Even when stabilized by persistent cold weather, they can be an impediment to glacier travel.

Seracs are found within an icefall, often in large numbers, or on ice faces on the lower edge of a hanging glacier. Notable examples of this type (overhanging glacier edge)are well-known obstacles on some of the worlds highest mountains, including K2 at The Bottleneck or Kanchenjunga on the border of India and Nepal. Significant seracs in the Alpsare found on the northeast face of Piz Roseg, the north face of the Dent d'Hérens, and the north face of Lyskamm.

The collapse of large seracs was responsible for at least 8 of the 11 deaths of the August 2008 climbing accident on K2. In April 2014, a large serac broke off and caused an avalanche on Mount Everest, which was responsible for the deaths of 16 climbers.

On a 1970 Japanese expedition to Mount Everest Kyak Tsering was killed by a falling serac.

Serac, Russell Glacier in Greenland

Seracs in firn at 3,050 metres (10,000 feet) on the Winthrop Glacier of Mount Rainier in Washington, USA

Seracs, Bossons Glacier, southeastern France

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