Much more serious was a slush flow that struck the small coal mining settlement of Longyearbyen, Spitsbergen, on June 11, 1953. Not realizing the danger, people there built several houses and a hospital on a debris fan formed by earlier slush flows. This moving tongue slammed into the upper group of buildings and they disintegrated as if swatted into oblivion by a gigantic hand. This graphic description of the event that killed three and injured twelve persons was given by Fairbanks geologist Richard D. Reger at a recent Alaska Science conference. Slush flows occur during spring breakup in locations where an accumulation of snow becomes saturated with water.
Afternoon is the worst time for slush flows.
A small slush flow may be only a foot or so thick, but those thicker than 50 feet have been observed.