surge

A glacier surge is a phenomenon where a glacier, after a period of normal flow, suddenly begins to move at a much faster rate, sometimes up to five meters per hour. This rapid flow typically lasts only a year or two, causing the upper part of the glacier to deplete while the lower part swells and advances, though usually not beyond previous surge limits. These surging glaciers repeat cycles of activity and quiescence independently of climate changes. The cause is generally an abrupt decoupling of the glacier from its bed, often due to a breakdown in the subglacial water flow system, though the exact mechanisms are not fully understood. Glacier outburst floods, or jökulhlaups, can also occur when water is stored within or behind a glacier and is suddenly released.12