In DepthNatural Hazards

A debris-dammed lake threatens a flood

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Science  19 Aug 2016:
Vol. 353, Issue 6301, pp. 735-736
DOI: 10.1126/science.353.6301.735

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Summary

Earlier this year, workers raced to fix an engineered tunnel that drains Spirit Lake on the northeast flank of Mount St. Helens in Washington. Thirty-six years ago, the mountain erupted, killing 57 people and blowing a cloud of ash 20 kilometers high. It also sent an avalanche of rock, sand, and gravel down its north slope that crashed into Spirit Lake, blocking the river that drained it. In 1984, engineers bored a 2.6-kilometer-long tunnel to drain the lake so it wouldn't rise high enough to bust through the debris dam. If that happened, it would likely wipe out whole towns downstream, potentially killing tens of thousands of people. After earthquakes around the still-active volcano collapsed part of the tunnel last year, engineers fixed the collapse. But continuing seismic activity in the region ensures that such problems will reoccur. Now, a panel of scientists with the National Academy of Sciences is searching for a more lasting solution. Yet there is little agreement on the best path forward.

  • * in Kelso, Washington