Mount St. Helens at 40

The hydrogeomorphic legacy from a volcanically battered landscape endures American baseball legend Yogi Berra famously quipped “It ain't over till it's over.” That tautological phrase is apt for volcanology, especially with respect to eruptions that pummel landscapes with fragmental debris. Indeed, after such eruptions end, some of society's stiffest challenges may have only just begun. This year marks the 40th anniversary of the renowned eruption of Mount St. Helens on 18 May 1980. Its observation accentuates awareness that science and society still confront the costly and potentially lethal sediment and hydrologic hazards that linger from cataclysmic events that transpired within minutes on a sunny Sunday morning. Two key hydrologic and geomorphic (hydrogeomorphic) issues, the lingering hazard posed by a volcanically dammed lake and relentless sediment delivery to distant communities, remain as problematic legacies of the eruption.