But this morning was different. For weeks a previously little-known volcano had been stirring, and now it was preparing to catapult itself into the ranks of the world's most famous mountains. At 8:32 a.m., the upper slopes of Mt. St. Helens began to bulge sideways--like an artery about to pop an aneurysm or an automobile tire on the verge of a sidewall blowout. Then it happened, as the mountain blew its top--not upwards, but sideways, in a blast that would lay waste to more than 150 square miles.

The first wave of devastation was a shock wave that has been described as a "stone wind." It roared down the mountainside at hundreds of miles an hour--several times the speed of a class V hurricane--hurtling rocks, toppling trees, and flaying the land to a lifeless-looking gray expanse--a moorscape as bleak as the world's harshest deserts. That was followed, in quick succession, by the largest avalanche in recorded history (comprised of nearly 0.6 cubic miles of rock), mudflows, scorching heat, and billowing ash that turned day to dusk at least 100 miles downwind.

But the blast did more than rearrange the landscape; its intellectual aftershocks reordered scientific wisdom in two fields, volcanology and successional ecology. The changes are so wide-sweeping that scientific historians could easily divide both fields into pre- and post-Mt. St. Helens eras.

Jules Verne's Journey to the Center of the Earth aside, relatively few science fiction stories draw heavily on volcanology. But the blast rendered obsolete the scientific underpinnings of science fiction stories that meticulously constructed viable-seeming worlds based on pre-Mt. St. Helens notions of ecology. Terraforming and post-holocaust stories may also have to be reconsidered. And Mt. St. Helens' lessons on the effect of what ecologists euphemistically call "perturbances" are important to the design of multi-generation "universe" ships that substitute self-contained ecosystems for the need to carry hundreds or thousands of years of supplies. These same lessons also offer possible explanations for why one actual attempt to create such an ecosystem, the Biosphere project of the early 1990s, was such a miserable failure.

Although the chief implications for science fiction are likely to be in the realm of ecology, Mt. St. Helens has greatly broadened scientists' understanding of volcanic hazards. Let's look first at volcanology, then turn to some of the ecologists' more dramatic findings.