Mount St. Helens

Geographic Facts and Overview

Elevation: 8, 635 feet (2,550 m)

Prominence: 4, 605 feet (1,404 m)

Coordinates: 46°12’00.17”N, 122°11’21.13”W

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Age of rock: > 40,000 years

Easiest access: southern slope

Mount St. Helens is an active stratovolcano in Skamania County, Washington, in the Pacific Northwest region of the United States. It is located 96 miles south of the city of Seattle and 53 miles northeast of Portland, Oregon. Mount St. Helens takes its name from the British diplomat Lord St Helens, a friend of George Vancouver, who did a survey of this place in the late 1800s.

The mountain can be found in the Cascade Range and is part the Cascade Volcanic Arc, a segment of the Pacific Ring of Fire that includes over 160 active volcanoes (Mount St. Helens). This volcano is quite well known for its ash explosions and pyroclastic flows. It is located 45 miles west of Mount Adams, in the western part of the Cascade Range. These volcanic mountains are each approximately 50 miles from Mount Rainier, the highest of Cascade volcanoes. Mount Hood, the nearest major volcanic peak in Oregon, is 60 miles (95 km) southeast of Mount St. Helens. (Mount St. Helens)

Mount St. Helens is quite young compared to the other well-known Cascade volcanoes (Mount St. Helens). It only formed within the last 40,000 years, and the summit cone (before the 1980 eruption) began rising around 2000 years ago. The volcano is still considered the most active in the Cascades within the last 10,000 or so years, according to the Mount St. Helens report in Wikipedia.

Mount St. Helens Eruptive History

The early eruptive stages of Mount St. Helens are known as the “Ape Canyon Stage” (around 40–35,000 years ago), the “Cougar Stage” (ca. 20–18,000 years ago), and the “Swift Creek Stage” (roughly 13–8,000 years ago).The modern period, since about 2500 BC, is called the “Spirit Lake Stage”. (Mount St. Helens) Collectively, the pre-Spirit Lake Stages are known as the “ancestral stages” (Mount St. Helens).

The Eruption of May 18, 1980

Mount St. Helens erupts maybe around once each century. After lying asleep for 123 years, Mount St. Helens again spewed steam and ash on March 27, 1980 – a prelude that put geologists on alert. But what happened on the18th of May, 1980, went beyond what anyone had envisioned. According to Mount Saint Helens History report, a 5.1 magnitude earthquake from inside the volcano triggered the destruction of its north flank, letting down the largest landslide in recorded history and a volcanic eruption equal in power to 500 atom bombs (History). As much as a cubic mile of volcanic material shot upward and sideways.

The blast traveled at more than 300 miles per hour with temperatures in excess of 600 degrees F, destroying 230 square miles of forest (History).  Within seconds, the trunks of thousands of 150-foot-tall old-growth Douglas firs snapped like toothpicks. Ash rained down over 22,000 square miles, blew more than 12 miles into the atmosphere and circled the globe in 17 days (History).  When the ash finally cleared up, the mountain was reduced by 1,313 feet (History). Although the Forest Service and local authorities had worked hard to keep people away, 57 were killed.  Rocks, snow and ice roared down the mountain at enormous speeds (sometimes reaching more than 100 miles per hour). Most large animals on the volcano, like mountain goats, black bears, and thousands of elk and deer (even most fish, amphibians, insects and birds), died. (History)

Mount St. Helens before the Eruption

Before the eruption of 1980, Mount St. Helens formed an almost perfectly conical, youthful volcano that sometimes was known as the Fuji-san of America (Eruptive History). According to Volcano World’s Eruptive History page, during the 1980 eruption, however, the upper 400 m of the summit was removed by a slope avalanche, leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome.

The eruption of Mount St. Helens in 1980 changed the surrounding environment. Before the eruption, the areas around the mountain were known for its natural beauty. The Spirit Lake basin was said to be coated with ancient trees. The tree rings of these huge 800 year-old trees show evidence of eruptions that date back before the time of the Europeans arrival in the Americas (Biologic History).

A few research sites existed before 1980 and they showed a healthy, vigorous forest, growing on the rich volcanic soils typical of the Pacific Northwest (Biologic History). Under the dense canopy, huckleberries, ferns, and mosses grew. A wide variety of animals lived here. Above Spirit Lake, the alpine meadows on the mountain were slowly being overtaken by trees (Biologic History). The alpine meadows supported a wide variety of wildflowers and gnarled trees. Mountain goats were transplanted from the Olympic Peninsula. They were well known for their aggressive ways.

Sometimes they butted hikers right down the mountain (Biologic History). When people remember Spirit Lake, they always mention how clear it was (Biologic History). Fed by snow and glacial melt, the lake’s temperature was normally below 55 degrees Fahrenheit year round (Biologic History). The many types of microscopic plants and animals that fish eat did not do well in this cold water. Because of this, the fish that were stocked never managed to become a self-sustaining population (Biologic History). Some people will tell you that Spirit Lake was overflowing with fish. However, catch records indicate that it was just average for the Northwest. Those who visited Mount St. Helens before 1980, were always impressed by its natural beauty. (Biologic History)

Mount St. Helens Now

As amazingly destructive as it was, the May 18, 1980 eruption is just one of many events in the history of Mount St. Helens. Considering the 27 years and renewed volcanic activity, it is surprising to see how Mount St. Helens continually changes. The past 27 or so years have been characterized by a rebirth.  Within the crater, a new lava dome began rising in 1986, rebuilding the mountain (History).  A new glacier has established itself on the crater floor.   And since early October 2004, a second lava dome has grown at a rate as high as a dump-truck load in volume every second.

At this rate, scientists estimate Mount St. Helens could return to its height before the 1980 eruption of 9,677 feet in less than 200 years – less than a blink of the eye in geologic time (History). Remarkably, plant and animal life has revived itself faster than was expected. Beetles were among the earliest animals to return and over 300 kinds now flourish (History). Lupines, members of the pea family, were among the first plants to grow in the deep deposits of volcanic ash.

Scientists learned that lupines drive ecological recovery by creating islands of rich nutrients that promote establishment of other plant species (History).  Millions of new trees and animal species have also returned to the areas that most of them left in 1980.  Mount St. Helens is back to being a living playground. According to the Mount St. Helens Institute, it has become one of the most remarkable areas of geological and ecological disturbance and restoration in the world. This country has learned a lot from what happened 27, or so, years ago. We are now better prepared to face another eruption (to avoid the casualties of 1980), and scientists, our other learned friends in different fields of study, and the general public, are coming to experience the remarkable volcano that is Mount St. Helens.

The Current Eruptions

Mount St. Helens came alive again in the fall of 2004 and has continually been erupting. Plenty of news crews and visitors from around the globe have surged to the volcano.  Mount St. Helens has returned to its former grandeur and is now a leading recreational area, with more than 500,000 visitors a year.

W O R K S   C I T E D

“Mount St. Helens.” Wikipedia, The Free Encyclopedia. 22 Apr 2007, 19:46 UTC. Wikimedia Foundation, Inc. 24 Apr 2007 ;https://en.wikipedia.org/w/index.php?title=Mount_St._Helens;oldid=124937639;

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