Response and Recovery of Lakes

Abstract

The 1980 eruption of Mount St. Helens devastated vast forestlands, triggered massive landslides and mudflows, and emplaced timber and volcanic debris in nearby lakes. Tephra and pyrolyzed forest debris rained down on dozens of subalpine, oligotrophic lakes scattered across a fan-shaped area affected by the lateral blast of the May eruption. This blast area, which encompasses the debris-avalanche, pyroclastic-flow, blowdown, and scorch zones, covers roughly 570 km2 north of the volcano. An additional, extensive zone northeast of the blast area received tephra fall.