On May 18, 1980, after weeks of tremors, Mount St. Helens erupted spectacularly
and profoundly changed a vast area surrounding the volcano. Since then scientists
from the USDA Forest Service Pacific Northwest (PNW) Research Station, along
with other scientists from around the country, have used the volcano as a living
laboratory for ecological research. This Web site is the primary reference
on the Internet for information on the ecological responses to the Mount St.
Helens eruption.
Natural disturbances such as eruptions, floods, fires, and earthquakes
are heterogeneous events, meaning that the disturbance creates a complex mosaic
of disturbed areas and effects are not evenly distributed. The May 18, 1980,
eruption of Mount St. Helens involved several distinct large disturbances—a
huge debris avalanche, an explosive blast out the mountain’s north side,
mudflows, hurricane-force winds of hot gases, and ejected volcanic rock and
ash (tephra). These events interacted with a diverse landscape to create a
complex mosaic of disturbance zones covering
several hundred square miles. The severity of disturbance ranged from areas
where all life perished to zones with nearly complete survival.
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