Most glacier surges, broadly defined as a flow at least 10 and often hundreds of times faster than a glacier’s usual pace of advance, are quieter affairs. Many are imperceptibly slow, but others attain staggering speeds. In 1953, for example, Kutiah Glacier in Pakistan advanced 12 kilometers over 3 months. Besides overwhelming settlements, glacier surges can threaten distant communities. They can block rivers, creating lakes that can later unleash floods, and by depleting glacier mass, they can threaten the flow of meltwater that downstream towns and farms may depend on.