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Mount St. Helens

On May 18, 1980, Mount St. Helens, a snow-capped mountain in southwest Washington’s Gifford Pinchot National Forest, erupted. A debris avalanche—the largest in recorded history—along with a lateral blast, mud and pyroclastic flows, and airborne ash and stones instantly created a real-time laboratory for scientists that continues to transform and to intrigue scientists today (most recently with an episode of active lava dome growth that began in late 2004).

For about 12 years after the eruption, the deer mouse was the dominant mammal on the pumice plain. The deer mouse also survived in the blowdown zone. Photo by Charlie Crisafulli.
Scientists continue to monitor the recovery of life in permanent plots set up within weeks after the May 18, 1980, eruption. Photo by Charlie Crisafulli.
Small mammals helped spread plant seeds and fungi spores across the volcanic landscape. By 2005, nearly all of the small mammals native to the region had returned to the blast area. Photo by Charlie Crisafulli.
Mudflows buried vegetation and killed animals in stream channels. Some plants survived at the margins of mudflows. Photo by Charlie Crisafulli.
Research ecologist examines gopher caught in live trap. Small mammals trapped for research were released unharmed after data were recorded.
The intermittent stream channel across this rocky plain carries water only during snowmelt runoff or heavy rainstorms. Photo by Charlie Crisafulli.
Sun-loving prairie lupines thrived in dry, open areas. The lupine patches provided carbon and nitrogen to the nutrient-poor soil, which encouraged the establishment of other plants. As the green patches became more diverse, more animals were attracted to them, the animals unknowingly spread seeds and spores, and thus, a feedback loop was established. Photo by Charlie Crisafulli.
A research crew checks a small mammal trap. Open, barren areas such as this one offered little habitat to small mammals and were slow to be colonized. Photo by Charlie Crisafulli.
The deer mouse uses a wide variety of habitats and eats many foods, including insects as well as seeds and berries. Thus this species colonized nearly all of the disturbance zones in the blast area. Photo by Charlie Crisafulli.
Pyroclastic flows covered the land north of the volcano with pumice many feet deep. During summer 1980, helicopters landed crews on this sterile, desolate terrain, which came to be called the Pumice Plain. Photo by C. Crisafulli.
Fish biologists weigh and measure this healthy rainbow trout, caught from Spirit Lake. It took fish over a decade after the eruption to return to Spirit Lake, but fish are now thriving in the lake. Photo by Charlie Crisafulli.
Farther from the volcano, the eruption left only several inches of ash covering the ground. In this tephra-fall zone, most mammals, birds, and large trees survived, but most ground vegetation, insects, and other small organisms were smothered by the ash. Photo by Charlie Crisafulli.
The song sparrow nested in shrubs in the blowdown and scorch zones. Four speckled eggs are incubating in the song sparrow nest shown here. Photo by Charlie Crisafulli.
A snowcapped Mount St. Helens and blue sky are reflected in Spirit Lake in 2004, a few months before the volcano began to erupt again. Photo by Charlie Crisafulli.
Spotted sandpipers fed and nested along the lake shores in the blast area. Four eggs are incubating in this spotted sandpiper nest of twigs, bark, and moss. Photo by Charlie Crisafulli.
Hot volcanic gases killed the trees but left them standing in a scorch zone along the outer fringes of the blowdown zone. These dead trees, called snags, were used by insects and woodpeckers. Photo by Charlie Crisafulli.
In areas where all life perished, beetles were among the earliest colonizers, feeding on wind-carried insects. Photo by Charlie Crisafulli.
In the 25 years since the 1980 eruption, ground-dwelling beetle communities have changed as the habitat changed. (Beetle shown here has no common name.) The early pioneer species were replaced by caterpillar-hunting beetle species as the plant cover increased and moth caterpillars fed on the plants. Photo by Charlie Crisafulli.
Last updated December 9, 2025
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