surging glacier

a glacier that experiences a dramatic increase in flow rate, 10 to 100 times faster than its normal rate; usually surge events last less than one year and occur periodically, between 15 and 100 years.
In 1941, Hole-in-the-Wall Glacier surged, also knocking over trees during its advance. (Photo courtesy of the World Data Center for Glaciology, Boulder, CO. Photo probably taken by W.O. Field.)