Wednesday, March 9, 2005

Ash Tracker and Geology Queen For A Day

Update for Wednesday A.M.,
March 9, 2005

REMARKS:
Track map
Leading Edge of ash has entered Western Montana. Ash is becoming fainter or more diffuse in satellite imagery. The ash is currently moving eastward, but is expected to turn more south in the next several hours.
Next advisory will be issued 2005 March 09 at 1615

Matinee St. Helens:
Slide Show view of last nights Eruption?
Topo Map of the St. Helen's area?
Seismo-Cam?
Johnston Ridge Live Web Cam?

Ain't geology wacky? I love it!
It's one of the great things about The Pacific Northwest.
We have volcanic activity, we have the Juan DeFuca plate off the coast, we have Hikes in the gorge showing spetacular examples of the effects of erosion on basalt. There is Fort Rock in the middle what was once a gigantic lake that covered much of the southern half of the state of Oregon.

AND NOW FOR THE MEMOIRS OF HER HIGHNESS:

Recent History of Helen's Activity:
1979 — The mountain is a recreational haven. Half a million people a year visit the Spirit Lake area below the cone-shaped, 9,677-foot summit.
March 1980 — The volcano begins to show signs of unrest. Earthquakes and steam eruptions continue for several weeks.
8:32 a.m., May 18, 1980 — A 5.1-magnitude earthquake about a mile below the summit triggers a massive eruption and landslide, flattening 230 square miles of forest northwest of the summit and resulting in the deaths of 57 people. A plume of ash extends 15 miles into the sky and coats towns 250 miles away.
Summer 1980-October 1986 — Repeated minor eruptions build a 925-foot-tall dome of hardened lava inside the crater left by the eruption.
1982 — Congress and President Reagan create the 110,000-acre National Volcanic Monument for research, recreation and education. Inside the monument, the environment is left to respond naturally to the disturbance.
1990-present — Steady progression in the variety and number of plants and animals returning to the blast zone.
1998 — First major seismic activity since 1986, with earthquakes located as deep as 6 miles forcing magma to within about a mile of the dome, scientists believe.
2001 — Another flurry of small earthquakes, but once again, no magma surfaces.
Sept. 23, 2004 — The first of thousands of tiny, shallow earthquakes are recorded at St. Helens.
Sept. 26, 2004 — The U.S. Geological Survey declares a notice of volcanic unrest, closing the crater and upper flanks of the volcano to hikers and climbers.
Sept. 29, 2004 — Earthquakes increase to about four per minute, ranging in magnitude from 2.0-2.8. The USGS raises its warning system to the third of four levels and warns that a blast could send rocks and ash 3 miles from the summit.
Oct. 1, 2004 — Mountain briefly belches out a plume of smoke and ash. Quakes subside.
Oct. 11, 2004 — Molten rock reaches the surface, marking resumption of dome-building activity that had stopped in 1986.
March 8, 2005 — A large plume of steam is emitted from the crater, accompanied by an earthquake of about 2.0 magnitude at 5:25 p.m.


St Helens Expanded History
MOUNT ST. HELENS, Wash. -- There has been a volcano on this site for 40,000 years — the youngest and most active peak in a 1,000-mile Cascade Range chain that extends from Mount Garibaldi in Canada to Mount Lassen in Northern California.
Like the others, Mount St. Helens erupted, blasted itself apart and reformed several times over tens of thousands of years.
The perfect cone that blew apart in May 1980 began to form during the 500-year Pine Creek eruptive period that began in 1,000 B.C.
So the current mountain is about 2,500 years old — the blink of an eye in geological time, but a period that roughly covers the history of western civilization.
The pyramids in Egypt were already 2,000 years old when the current peak began to form. Greece and Rome rose and fell as it grew.
All the world's major religions developed as the cone rose above the forested mountains — Buddhism in 500 B.C., Christianity as the millennial clock turned from B.C. to A.D., Islam 600 years later.
The nations of Europe formed, dissolved and redesigned themselves as the centuries rolled.
To the west, the Aztecs were building pyramids in 1200, the Mayans about 500 years later. European explorers ventured to the New World in the late 1400s, followed by colonists and settlers.
The Klickitat and Cowlitz tribes, who had already inhabited the area for centuries, called the peak "mountain of fire" in their languages.
In 1792, British explorer George Vancouver named the mountain for a countryman, diplomat Baron St. Helens.
In 1836, Dr. Meredith Gairdner of Fort Vancouver logged the first written eyewitness report of an eruption.
In 1980, it erupted, reducing its height by 1,300 feet. Debris was spread as much as 17 miles northwest of the crater. The blast destroyed more than 200 square miles of forest, covered the river valley to the west with an average 150 feet of debris and killed 57 people, about 7,000 big-game animals and countless smaller creatures.




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