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EARTHWATCH

Volcanic fury

Excitement over watching Mt. St. Helens has not abated. It is all about the cycle of life, says SHIELA IYER.

AP/U.S. GEOLOGICAL SURVEY, JOHN PALLISTER

In 2004 -- Mt. St. Helens erupts.

SUNDAY morning, May 18, 1980. Time: 8.32 a.m. Mt. St. Helens erupts. Ash and pumice are hurled out of the volcano. Huge chunks of volcano debris called hummocks fall into the valley below. Clouds of ash and dust rise 20 miles upwards, darkening the sky and spreading downwind towards Eastern Washington State, enveloping the entire area in dust. The entire northern flank of the mountain collapses and falls as an avalanche lowering the height of the mountain by 1,500 feet. This forms the largest landslide in recorded history. Gas rich magma and heated groundwater from inside the volcano are suddenly released in a powerful lateral blast. The enormous amount of debris buries the surrounding forests. An area of 230 square miles was flattened in less than three minutes. Fifty-seven people lost their lives. Countless species of wildlife were scalded to death. The eruption lasted nine hours. At the end of it, the landscape had changed from lush green forest to an ashen grey wasteland.

The `visitor centre'

May 29, 2004: My sister and I are on a visit to Mt. St. Helens, an active volcano at a height of 8,364 ft in the state of Washington, U.S., about three hours and 100 miles south of Seattle. Going up the winding hills, we see hillsides green with pines and Douglas firs. We arrive at the Johnston Ride Observatory, which lies five miles north of the crater and is at a height of 4,255 ft. A "visitor centre" here, which is the visitor centre closest to the crater, explains how volcanoes are formed and why they erupt. As everywhere else in the U.S., the "visitor centre" here too has well laid out and detailed information with models, interactive videos and exhibits (I wish we could emulate this in India). A short film is shown which takes us through the big eruption. Preceding the blast of May 18, a series of rumblings and small earthquakes had been recorded which warned the scientists of a pending eruption. An earthquake measuring 5.1 on the Richter Scale was recorded on that day. The film details the destruction that followed and ends with the entire length of curtains in the darkened hall being raised to expose the majestic Mt. St. Helens in all its present glory rising in the background. The effect is so dramatic that for a moment, everybody in the audience catches his/her breath! It's a magnificent view.

Clouds play hide and seek with the mountain now exposing, now hiding the summit from our view. When the clouds lift, the sight of the mountain range is all the more beautiful. Streaks of brown criss-cross down the mountain slopes where rivers of ash and pumice would have once flowed. We were told at the "visitor centre" that Mt. St. Helens had a "Pyroclastic flow", which is an eruption of volcanic ash and pumice as opposed to molten lava. The hot gases and magma melted the ice and snow that covered the mountain and the resulting mudflow continued throughout the night and the following day. We now see deep trenches marking the path of pyroclastic flow. The landscape here is still a vast area of grey brown covered mostly with volcanic ash, dust and rock (a pumice plain).

There are short trails and viewpoints to see Spirit Lake which lies on the north side and was partly dammed by the falling rock and debris. A few miles downhill is "Coldwater Ridge Visitor Centre" at a height of 3,091 ft. Unlike Johnston Ride, the hillsides overlooking this "visitor centre" are covered in a canopy of green, and the Coldwater Lake lies silently below in all its pristine beauty. A forest ranger tells us that all plant and animal life here was allowed to redevelop naturally. It seems almost incredible that the greenery we see all around is not planted, and has sprouted from the barren wasteland that resulted from the big explosion.

Nature bounces back

In 1982, 1,10 000 acres was set aside as Mt. St. Helens National Volcanic Monument and all vegetation in this area (or whatever was left of it) was left to respond naturally to the environment. While geologists and volcanologists study the crater area, biologists here study how native flora and fauna can grow and develop in a hostile environment without any intervention by man. The ranger, with the help of charts takes us through the revegetation process. Gophers and other rodents which survived the blast underground, dug tunnels through the soil turning the soil over. Seeds dispersed by wind fell on the soil leading to the appearance of hardy plants like fireweed and lupine. Small insect life and birds returned and more dispersal of seeds took place through feathers and animal scat. Incredible as it may seem, in a decade's time enough vegetation had appeared to feed large animals like the elk and the moose. In a period of 15 years, plant life had increased considerably and small reservoirs had appeared on the hummocks. And in 24 years we see that nature has worked a miracle-an entire ecosystem is in place where once there was nothing. This shows the interdependency between different life forms and the cycle of life goes on.

Friday October 1, 2004: Mt. St. Helens reawakens. Volcanologists have recorded rumblings and tremors over the last few weeks. This noon ash and smoke spew out of the volcano. This has been the biggest eruption after 1980. The Johnston Ridge Observatory has been closed to visitors. Trekkers to Spirit Lake have been turned back. Visitors make a beeline for the "Coldwater Ridge Visitor Centre", the nearest one open to the public. People arrive from all over the country just to see the volcano erupt and be a part of its history. Will it erupt? Scientists are closely monitoring the seismic activity of the mountain. Cracks on the volcano's lava dome and the smell of hydrogen sulphide gas near the crater were indications to them of the impending eruption. Steady rumblings have been recorded indicating the upward movement of magma. The 1,000 ft high lava dome has increased in height by 150 ft.

At present: Johnston Ridge Observatory continues to be closed to visitors. The U.S. Forest Service believes Mt. St. Helens is in a state of intense unrest and will continue to go through bursts of activity over a period of the next few days, weeks or even months. In the meantime, the excitement among the watching public continues unabated.

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