The earthquake, a trick of nature that no one had anticipated, hit Mount St. Helens at 8:32 a.m. on Sunday, May 18, 1980, triggering 15 minutes that seem frozen in time, an incredible snapshot in the life of the volcano.
The quake shook loose the largest landslide in history, releasing a volcanic explosion that blew the summit off the mountain.
A blast cloud, hot enough to melt plastic and traveling near the speed of sound, literally vaporized objects in its path. A plume of ash rose to the stratosphere and eventually circled the Earth.
In a quarter hour, the mountain, once a scenic gem, reduced itself to an ugly, steaming hulk. It happened 10 years ago today.
That terrible day began quietly. The skies were clear, temperatures mild. Seismicity under the mountain, rumbling for two months, was moderate, about the same as it had been in the previous few weeks.
Dave Johnston, at a U.S. Geological Survey observation post about six miles north of Mount St. Helens, made two laser measurements of an ominously growing bulge on the volcano and had radioed the numbers to Vancouver by 7 a.m.
Keith and Dorothy Stoffel were approaching the mountain in a plane they had chartered in Yakima. The Stoffels, geologists from Spokane, were armed with cameras.
On a ridge two miles north of Johnston's post,
Gerald Martin, a retired Navy radioman who had
volunteered as a volcano watcher for the state, had checked in with a network of ham radio operators ringing the mountain.
And in Vancouver, C. Dan Miller of the Geological Survey was ready to drive an armored personnel carrier, borrowed from the Washington National Guard, to Johnston's post. The Survey thought the heavy vehicle would be a safer refuge than Johnston's trailer - just in case.
The earthquake, 5.1 on the Richter scale, shattered the tranquil morning. It jiggled loose the unstable bulge Johnston had been monitoring. As the whole north side of the mountain slid, it removed the lid that had bottled up pressurized magma inside the mountain. The gas-filled magma exploded, sending a hot, debris-filled blast cloud to the north.
The Stoffels, about 2,000 feet above the summit, didn't know about the earthquake. But they watched in amazement as the north side of the mountain seemed to ripple and churn for about 10 seconds before beginning to slide. Then a huge explosion ripped through the sliding slab, sending a black cloud billowing toward the plane.
The pilot, Bruce Judson, put the plane into a dive to gain speed and headed south. It was several minutes before they were sure they had outrun the cloud, which could have blown the plane apart and burned the pieces. They landed safely in Portland.
Johnston undoubtedly felt the earthquake. He was on the radio immediately, shouting, ``Vancouver, Vancouver, this is it!'' The message never got to Vancouver but was reported by a ham radio operator.
A few ridges away, Martin coolly radioed a description of the avalanche, the explosion and the dark cloud. He added: ``The car and camper (Johnston) just over to the south of me are covered. It's going to get me, too.''
Johnston and Martin were among the 57 killed or missing in the eruption.
Miller doesn't think even the armored vehicle would have saved Johnston. The blast cloud hit the post at an estimated 670 miles an hour, carrying temperatures estimated as high as 570 degrees Fahrenheit.
Climbers on Mount Adams, 34 miles east of St. Helens, watched the dark eruption cloud, but heard nothing. They felt a heat wave after 10 minutes.
Beyond a zone of quiet around the mountain, people did hear the volcano's voice.
In Seattle, it was as though houses were hit by a padded wrecking ball. Some people said they felt, as well as heard, the ``whump.'' Residents in the San Juan Islands thought the Canadian navy was having gunnery practice. Along the Oregon coast, it sounded like a sonic boom.
Instruments on the East Coast detected a low-frequency rumble three hours and 20 minutes after the eruption. Recording barometers as far away as Helena, Mont., and Las Vegas, Nev., picked up a momentary pressure change.
The volcano's human victims probably died within minutes, killed by heat and impact of the blast, suffocated by ash and debris blown out of the mountain or buried by the landslide. But St. Helens continued its spectacular show all day.
The wind played tricks with the eruption's thick ash column, which persisted for nine hours, rising more than 12 miles. Ritzville, 195 miles from the volcano, was blanketed with 2 inches of ash, twice as much as Yakima which is only half as far from St. Helens.
Cars skidded on slippery ash on Eastern Washington roads. Highways were closed, stranding travelers for days. Westbound trains stopped in North Dakota and Montana to avoid entering the equipment-damaging ash cloud.
Huge mudflows from the volcano took hours to build up, giving people time to get out of the way. Steaming hot mud began moving down the North Fork of the Toutle River about noon. It moved slowly, probably less than 20 miles an hour, but nothing could withstand it. The stream was so dense that pieces of steel bridges, houses, even a loaded logging truck, floated on it.
Motorists waiting at the Interstate 5 closed bridge over the Toutle River watched in fascination as wrecked cabins, vehicles or pieces of bridges bumped into the span and then scraped noisily beneath it.
Rescue workers and scientists in helicopters began reporting that the top of the mountain was gone - more than 1,300 feet. The blast had devastated 230 square miles. Steaming mud had filled valleys as deep as 600 feet.
The terrible day had finally ended.