Mount St. Helens is an active volcano in the Northwest region of the United States. This volcano is a stratovolcano and is situated in a segment of a volcanically active region known as the Pacific Ring of Fire. Mount St. Helens is most commonly known for the eruption that occurred on May 18, 1980, during which a vast area around the volcano was ecologically transformed. More than 30 years after the eruption, Mount St. Helens is still going through a series of ecological and geological reconfigurations. The Congress of the United States created the Mount St. Helens National Monument in 1982 as a site for recreation, research and education.
The eruption
The eruption of Mount St. Helens is considered the most catastrophic natural event in the history of the United States. During the eruption, layers two to three feet thick of tephra (pumice) and ash ejected from the volcano were deposited in areas surrounding the volcano, while a thin layer of the same material was spread several miles away from the volcano. Pyroclastic flows accumulated in deposits of more than 100 feet. Mudflows, originated by the melting of the volcano´s snow, destroyed the landscape in their path, travelling many miles downhill. The eruption created a crater 1.6-3.2 km (1-2 miles) wide. The eruption killed 57 people, 7,000 big animals, and 12 million fish, and destroyed several square miles of natural landscape.
Reconstruction
A group of scientists has studied the processes of the reconstruction of the volcano´s ecosystem for more than 30 years. Repeated observations over the past three decades have changed the way in which ecologists think about the ecology of disturbed areas and proper management afterward. It was believed that the flora and fauna at the edges of the perturbed areas would colonize the altered landscape; however, the recolonization was done by species that survived the eruption in widely distributed remote areas. Over time these scattered territories merged together, establishing larger communities, thus enriching the flora and fauna diversity.
Importance to geology
Mudflows, avalanches and volcanic debris damaged 380 square miles of the Cascade Range in southern Washington. Areas outside the Mount St. Helens monument were replanted with Douglas fir and noble fir trees, while the monument was left to respond naturally to the disaster. In areas of debris avalanche deposits, red alder is one of the dominant trees, while in the devastated zone several combinations of tree species are found. Species of herbs, shrubs and shade-enduring trees survived the eruption under the protection of a cover of snow. Many trees, including the mountain hemlock, silver fir and vine maple, grow intermixed with fireweed and pearly everlasting. This has broadened scientists’ understanding of natural succession.
National monument
The aftermath of the mount St. Helens eruption has provided scientists with a unique opportunity to study the ecological processes of succession. Recognizing the great opportunity to do research, the U.S. Congress established the Mount St. Helens National Monument in 1982, allowing 106,255 acres within the monument to continue developing the natural ecological reconstruction. Scientists arrived within weeks of the eruption to assess the effects and develop initial and long-term ecological responses. Their studies have contributed to enhance knowledge about the way in which species and the environment respond to the damage; furthermore, their research has allowed planning ahead for the recovery of other damaged areas.
Since its eruption, Mount St. Helens has become the most studied volcano in the world. The scientific discoveries and the different ways of managing long-term research are presently applied in other parts of the world. The science performed at the site of the eruption allows scientists to observe the natural processes that might take place in the lapse time of thousands to millions of years. The aftermath of the eruption left a barren landscape susceptible to invasive species. Erosion, avalanches and flood have contributed to define areas of ecological recovery. According to the U.S. Department of Agriculture, the eruption of Mount St. Helens transformed its landscape, including forests, lakes, meadows, rivers and streams. The eruption created research opportunities on the way in which plants and animals respond to disturbance and the long-term natural process of succession.
