The dictionary meaning of ‘surge’ is a heavy forward or upward motion. Glacial surge implies the sudden increase in the rate of movement of a glacier, even though for a short period of time.

It represents the glacier’s response to a change in its mass balance, which results in the sudden advance of the snout. Glacial surge is a type of accelerated flow, which exceeds the normal rate of glacier flow by four to six times.

Some of the Alaska glaciers in 1966 advanced at an abnormally high rate. In another case, during a 1953 surge, the Hassanabad glacier (Karakoram) advanced 10 km in 21/2 months at a rate of 130 m/day.

Besides a change in the glacier’s mass, there are other causes such as, earthquakes or high geothermal heat flow in the underlying rocks.

ADVERTISEMENTS:

In addition to the aforementioned causes, glacial surges are initiated by an instability produced because of the extraordinarily high accumulation of snow in the accumulation zone. This results in the growth of the bulk of a glacier.

Thus, the extraordinary increase in the slope of the glacial surface disturbs its equilibrium. Under such conditions any triggering mechanism like an earthquake shock starts the surge.

It may be mentioned that glacial surges prove to be very destructive and dangerous. Besides damage to farms and other components of cultural environ­ment, large quantities of melt, water causes unprecedented floods.

Sometimes, it may build a natural dam across a stream and thus create a natural lake. Sometimes, the cause of glacial surges could be the presence of a water-saturated layer of sediment beneath the glacier. However, the exact cause of the glacial surge is being investigated into.