?

Log in

No account? Create an account
atom

This Day in History, 1980: Mount St. Helens Erupts

(Today's historical post is dedicated to scarlettina.)

Twenty-five years ago today, on May 18, 1980:

At 8:32 a.m. PDT, Mount St. Helens, a volcanic peak in southwestern Washington, suffered a massive eruption, killing 57 people and devastating some 210 square miles of wilderness.


Called Louwala-Clough, or "the Smoking Mountain," by Native Americans, Mount St. Helens is located in the Cascade Range and stood 9,680 feet before its eruption. The volcano has erupted periodically during the last 4,500 years, and the last active period was between 1831 and 1857. On March 20, 1980, noticeable volcanic activity began again with a series of earth tremors centered on the ground just beneath the north flank of the mountain. These earthquakes escalated, and on March 27 a minor eruption occurred, and Mount St. Helens began emitting steam and ash through its crater and vents.

Small eruptions continued daily, and in April people familiar with the mountain noticed changes to the structure of its north face. A scientific study confirmed that a bulge more than a mile in diameter was moving upward and outward over the high north slope by as much as six feet per day. The bulge was caused by an intrusion of magma below the surface, and authorities began evacuating hundreds of people from the sparsely settled area near the mountain. A few people refused to leave.

On the morning of May 18, Mount St. Helens was shaken by an earthquake of about 5.0 Richter magnitude, and the entire north side of the summit began to slide down the mountain. The giant landslide of rock and ice, one of the largest recorded in history, was followed and overtaken by an enormous explosion of steam and volcanic gases, which surged northward along the ground at high speed. The lateral blast stripped trees from most hill slopes within six miles of the volcano and leveled nearly all vegetation for as far as 12 miles away. Approximately 10 million trees were felled by the blast.

The landslide debris, liquefied by the violent explosion, surged down the mountain at speeds in excess of 100 miles per hour. The avalanche flooded Spirit Lake and roared down the valley of the Toutle River for a distance of 13 miles, burying the river to an average depth of 150 feet. Mudflows, pyroclastic flows, and floods added to the destruction, destroying roads, bridges, parks, and thousands more acres of forest. Simultaneous with the avalanche, a vertical eruption of gas and ash formed a mushrooming column over the volcano more than 12 miles high. Ash from the eruption fell on Northwest cities and towns like snow and drifted around the globe within two weeks. Fifty-seven people, thousands of animals, and millions of fish were killed by the eruption of Mount St. Helens.

By late in the afternoon of May 18, the eruption subsided, and by early the next day it had essentially ceased. Mount St. Helens' volcanic cone was completely blasted away and replaced by a horseshoe-shaped crater-the mountain lost 1,700 feet from the eruption. The volcano produced five smaller explosive eruptions during the summer and fall of 1980 and remains active today. In 1982, Congress made Mount St. Helens a protected research area.


Personal note: Even thought I was only ten years old at the time, and living in New York City, I remember this event vividly. The news media covered the mini-eruptions with great enthusiasm, and every day we waited anxiously to find out if the volcano had finally erupted.

As often, today's post was taken from http://www.historychannel.com/tdih/tdih.jsp?month=10272957&day=10272983&cat=10272946

Also see http://en.wikipedia.org/wiki/1980_Mount_St._Helens_eruption for even more detail.
Tags:

Comments

I remember what happened 3 days later even more. The sky turned orangish brown in Southern California as the ashes drifted south. It got in and on everything. Even blowing your nose turned the kleenex funny colors.
I was about two months old at the time, but as a kid I developed an interest in volcanoes. The most prominent memory of my volcano phase is of learning the story of David Johnston, a research scientist working at Coldwater Observation Post, a few miles north from the main crater.

There had been less activity at Mt. St. Helens in May, and geologists in the area had not expected an eruption at the time. On the morning of May 18, Johnston's geological base in Vancouver received a brief message via two-way radio:

"Vancouver, Vancouver! This is it!"

They were Johnston's last words. It was 8:30 AM, and he was almost immediately killed by the four cubic kilometers of rock, hot gas, and ash that erupted from the mountain shortly thereafter.

The U.S. Geological Survey named the David A. Johnston Cascades Volcano Observatory after him. But those five words I read at the Museum of Science ("Vancouver! Vancouver!") have stuck with me for years.
I've been to the Johnston Observatory. His story is still told there and he's spoken of with great respect.
I remember it vividly as well, and was just slightly younger than you. It was the first time I'd seen really vivid footage of a natural disaster that wasn't a hurricane, and when I first learned just how far a relatively ordinary volcano's devastation--and the ash cloud--could go. I was in my elementary school's gifted program at the time, and it became the centerpiece of our curricula for that semester.
One of my souviners of Seattle is a square vial of ash, taken at three different distances, which clearly shows that the ash that fell 20 miles away is much finer than that which fell 5 miles away, and coarser still is the ash from 1 mile away. (Yes, I bought dirt.)

While volcanic eruptions cause massive damage, they also renew the ecosystem, bringing minerals to the surface, restoring the pH balance, and allowing forest turnover.

My impression of the mountain was that it was impossibly high--it looks like a strage, low cloud as it towers over the rest of the range.
I remember the day the ashes were supposed to pass over Massachusetts. It rained, so we couldn't see them :P

Oh Yes, I remember It Well...

I was 23 and pregnant with Leslie. We were living in Ohio, and I'd been watching for news of this for a while (it had been a big news story since March).

And then, it became a HUGE news story.

Jim, Leslie and I visited Mt. St. Helens in July 1990. It's an amazing place to visit. You drive through this forest, go up a ridge...and, suddenly, there's no forest for about 8 miles in any direction. But by 1990, this "moonscape of dead trees" was starting to come back to life. There were some bushes and flowers here and there.
From what I recall reading, if the wind had been going a different direction, Portland (50 miles away) would've been a major disaster area with large loss of life from secondary effects of the ash and its accompanying logistics problems. From a bit on what did happen;

The ash fall, however, did pose some temporary major problems for transportation operations and for sewage-disposal and water-treatment systems. Because visibility was greatly decreased during the ash fall, many highways and roads were closed to traffic, some only for a few hours, but others for weeks. Interstate 90 from Seattle to Spokane, Washington, was closed for a week. Air transportation was disrupted for a few days to 2 weeks as several airports in eastern Washington shut down due to ash accumulation and attendant poor visibility. Over a thousand commercial flights were cancelled following airport closures.

The fine-grained, gritty ash caused substantial problems for internal-combustion engines and other mechanical and electrical equipment. The ash contaminated oil systems, clogged air filters, and scratched moving surfaces. Fine ash caused short circuits in electrical transformers, which in turn caused power blackouts. The sewage-disposal systems of several municipalities that received about half an inch or more of ash, such as Moses Lake and Yakima, Washington, were plagued by ash clogging and damage to pumps, filters, and other equipment. Fortunately, as these same cities used deep wells and closed storage, their water-supply systems were only minimally affected.

The removal and disposal of ash from highways, roads, buildings, and airport runways were monumental tasks for some eastern Washington communities. State and Federal agencies estimated that over 2.4 million cubic yards of ash-equivalent to about 900,000 tons in weight-were removed from highways and airports in Washington State. Ash removal cost $2.2 million and took 10 weeks in Yakima.


Now, imagine that sort of thing happening in a large city. Water supply? Getting food in when engines are damaged just by travelling in the area? Etc.
I was living south of Tacoma. We could see the ash plume on the southern horizon. However, it all went east; Chicago got ash, we didn't.
Thanks for the dedication! ::chuckle::

Mt. St. Helens is an amazing place to visit today. It's still a moonscape five miles fromthe crater, but at that border, plant and animal life has taken hold again in a beautiful and aggressive way. I was there two summers ago, and the rangers were talking about how elk returned relatively soon after the eruption and are in the area in great abundance now. Wildflowers bloom all around Johnston Observatory, and tour groups hike all over the area.

With last year's new burst of activity, of course, hiking as been curtailed. Every now and then, if you click over to the Mt. St. Helens VolcanoCam, you can see little streams of smoke emitting from the new and growing cone. It's an awesome and spectacular place.
atom

December 2016

S M T W T F S
    123
45678910
11121314151617
18192021222324
25262728293031
Powered by LiveJournal.com