On May 18, 1980, Mount St. Helens erupted in western Washington. It was the most devastating volcanic eruption in U.S. history. Fifty-seven people were killed. Hundreds of homes, businesses, roads, and bridges were destroyed. Material from the eruption—called a pyroclastic flow—destroyed 595 square kilometers (230 square miles) of forest. The volcano ejected a plume of ash 19-24 kilometers (12-15 miles) into the air, and volcanic ash was detected as far away as eastern Oklahoma.The eruption of Mount St. Helens provided volcanologists with very useful data. Scientists tracked the volcano’s activity before it erupted, for instance, and noted that the eruption came after a series of earthquakes, the largest of which was a magnitude 5.1 that struck directly beneath the volcano just minutes before it erupted.
Term Part of Speech Definition Encyclopedic Entry data Plural Noun
(singular: datum) information collected during a scientific study.
to ruin or make useless.
the sudden shaking of Earth's crust caused by the release of energy along fault lines or from volcanic activity.
to get rid of or throw out.
to explode or suddenly eject material.
a building or room that serves a specific function.
ecosystem filled with trees and underbrush.
single, upward flow of a fluid, such as water or smoke.
pyroclastic flow Noun
current of volcanic ash, lava, and gas that flows from a volcano.
Encyclopedic Entry: pyroclastic flow research Noun
scientific observations and investigation into a subject, usually following the scientific method: observation, hypothesis, prediction, experimentation, analysis, and conclusion.
person who travels for pleasure.
volcanic ash Noun
fragments of lava less than 2 millimeters across.
Encyclopedic Entry: volcanic ash volcano Noun
an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.
Encyclopedic Entry: volcano volcanologist Noun
scientist who studies volcanoes.