|
-SPONSORED LINKS-
Mount St. Helens LodgingMount St. Helens Hotels Mount St. Helens Maps Mount St. Helens Camping Mount St. Helens Weather Mount St. Helens Vacation Rentals |
|
Sponsored National Park Search |
|
|
|
After many months of lead-up activity including earthquakes, an enormous bulge forming on the north face of the mountain, and minor landslides and mudslides, Mount St. Helens catastrophically erupted on May 18, 1980. The eruption was triggered by a magnitude 5.1 earthquake, which caused a massive collapse of the bulge on the north face. The resulting flow was the largest debris flow in recorded history, and as the land gave way to the pressurized rock below, the magma within the mountain burst forth in an eruption that devastated the surrounding landscape, killed 57 people, destroyed over 185 miles of highway, and reduced the height of the dome by about one third.
In 1982, President Ronald Reagan and the US congress established Mount St. Helens National Volcanic Monument within the Gifford Pinchot National Forest. Since the eruption, the area has been left to recover naturally.
110,000 acres or 172 square miles
Mount St. Helens is one of the most active volcanoes in the Cascade Range. The Cascade volcanoes define the Pacific Northwest section of the Ring of Fire, a series of volcanic regions that rim the Pacific Ocean. The Ring of Fire is known for its seismic activity, and both the volcanoes and the earthquakes are a result of the same process: subduction. In the case of the Cascade Range and Mount St. Helens, a dense oceanic plate plunges underneath the North American Plate. As the water saturated rock is drawn towards the earth's core, the heat and pressure cause the water molecules embedded within the rock to escape. As the water vapor rises into the more pliable mantle above the subducting plate, causing some of the mantle to melt into magma. This magma rises towards the earths surface to erupt, forming the Cascades above the subduction zone.
The blast killed an estimated 7000 large mammals like deer, elk, and bear. Most birds and small mammals (excepting burrowing mammals like marmots) were killed in the blast, along with about 12 million chinook and coho salmon fingerlings and about 40,000 wild young salmon.
Over time, many of the wildlife populations most devastated by the eruption have returned. The mountain is host to returning populations of Roosevelt Elk, Columbia Black Tailed Deer, and Mountain Goats. Many smaller mammals such as marmots and squirrels have returned to the mountain. The changed landscape created hundreds of small ponds, which were slowly populated with insects and amphibians, and the streams are now host to populations of returning fish. Bird populations have largely recovered, nesting in the dead trees and fertilizing the nearby ground.
Within the blast zone to the north of the dome, plant recovery has been slow to take hold in the nutrient poor soil. Outside the blast zone, forests of Douglas Fir, western red-cedar and noble fir, along with red alder, maple, and cottonwood remain. Within monument boundaries, nature is being left to take its course. Over time, observers have witnessed a gradual but unmistakeable "greening" of the landscape, with young groundcover slowly taking root in the soil. Experts predict a healthy young conifer forest by mid-century, and an ecosystem similar to the pre-blast ecosystem in roughly two centuries.
