Bursting ice dam in Alaska highlights risks of glacial flooding around the globe

JUNEAU, Alaska (AP) — The gray, two-story home with white trim toppled and slid, crashing into the river below as rushing waters carried off a bobbing chunk of its roof. Next door, a condo building teetered on the edge of the bank, its foundation already having fallen away as erosion undercut it.

The destruction came over the weekend as a glacial dam burst in Alaska’s capital, swelling the levels of the Mendenhall River to an unprecedented degree. The bursting of such snow-and-ice dams is a phenomenon called a jökuhlaup, and while it’s relatively little-known in the U.S., researchers say such glacial floods could threaten about 15 million people around the world.

“We sat down there and were just watching it, and all of a sudden trees started to fall in,” Amanda Arra, whose house continued hanging precariously over the river bank Monday, told the Juneau Empire. “And that’s when I started to get concerned. Tree after tree after tree.”

The flooding in Juneau came from a side basin of the awe-inspiring Mendenhall Glacier, which acts as a dam for the rain and melted snow that collect in the basin during the spring and summer. Eventually, the water gushed out from under the glacier and into Mendenhall Lake, from which it flowed down the Mendenhall River.

https://apnews.com/article/alaska-glacier-dam-flooding-jokuhlaup-95f06f4e0d82445705d3126aac004f5a