The eruption of Mount St. Helens on May 18, 1980, caused the destruction of 27 bridges, over 200 homes and 4.7 billion boards of timber. In addition, 15 miles of railway and 185 miles of highway were damaged or destroyed. Fifty-seven people also lost their lives during the eruption, and another four deaths occurred as an indirect result of the eruption.Continue Reading
In the immediate area, immeasurable damage was caused to the forest area from falling ash, lahars, flooding and mudslides. In the direct blast zone closest to the eruption site, everything within an eight-mile radius was completely obliterated. Aside from the destruction of buildings, cars and forestry, thousands of animals were killed.
When Mount St. Helens erupted, the ash column rose 12 miles high. The ash settled over Washington, Oregon and Idaho, and it even reached Colorado, Minnesota and Oklahoma. The settlement of ash caused the destruction of acres of crops, and thousands of dollars were spent on clean-up efforts. In all, the eruption of Mount St. Helens cost over one billion dollars in damage.
The eruption of Mount St. Helens also had many secondary effects. For example, local tourism was affected by the eruption, and unemployment increased significantly in the area surrounding Mount St. Helens.Learn more about Volcanoes
Mount St. Helens has erupted numerous times in its 300,000-year history, most notably on May 18, 1980. While much of its early history remains a mystery, geologic studies have concluded that Mount St. Helens is the most active volcano in the Pacific Northwest.Full Answer >
The catastrophic Mount Saint Helens volcanic eruption that took place on May 18, 1980 was the result of several factors that began with an accumulation of magma within the mountain's edifice earlier that year. A resulting bulge on the mountain's north flank was further weakened when an earthquake triggered a debris avalanche that relieved the pressure that had been acting as a counter-force to the magma buildup. Relieving the pressure resulted in the water that was contained within the system turning into steam, which then forced its way out explosively through a landslide scar.Full Answer >
Mount St. Helens' 1980 eruption was related to complex interactions between the Pacific Plate, the North American Plate and the much smaller Juan de Fuca Plate. It was the first major eruption to take place in the 48 contiguous U.S. states since Mount Lassen erupted in 1915.Full Answer >
While it is not yet possible to predict volcanic eruptions decades in advance, the U.S. Geological Survey’s Cascades Volcano Observatory continually monitors Mount St. Helens to gather data for more accurate short-term predictive models. According to “Future Eruptions at Mount St. Helens,” this volcano is the most likely to erupt in the Cascade Mountains of Washington again in the coming decades.Full Answer >