As the earthquakes shuddering within Mount St. Helens’ lava dome grew bigger and more frequent Thursday, the mountain’s unrest stirred many local residents’ memories about the eruption 24 years ago.
“Nobody could believe it. It was like the talk after 9/11 – ‘Can you believe it, what happened?’ ” recalled Deer Park insurance agent Ron Brazington, who swept the heavy ash off his grandmother’s roof after the 1980 eruption. “Things like that don’t happen in Washington.”
“It was so outside of anything you can imagine,” said Angela Brown, then a 13-year-old girl who rode her bicycle through Spokane’s ash-blanketed streets, a scarf tied over her mouth and nose.
Scientists – dozens of whom have been studying the mountain intently for a week – said Thursday that there’s a 70 percent chance of a “volcanic event” within days or weeks. But all signs indicate that it won’t be anything like the May 18, 1980, blast, which killed 57 people, blew off the top of the mountain, and showered much of Eastern Washington with inches of cementlike ash.
Two visitors’ centers within a few miles of the volcano remain open, although some hiking and camping has been curtailed in areas up to 12 miles from the mountain. And weather experts said Thursday that prevailing winds over the next few days would likely steer any ash cloud to the south or southwest, rather than east.
The mountain has remained fairly quiet since 1986, after more than a dozen outpourings of lava that gradually built a dome inside the 1980 blast crater.
Late last week, geologists monitoring the mountain noticed an increasing number of tiny earthquakes in the dome. At first, they attributed the shaking to heavy rainfall that was seeping down, hitting hot rock and turning to steam.
Now they’re not so sure. Days after the rains stopped, the earthquakes are growing stronger and more frequent. There have been several thousand in the past week. On Thursday, they were occurring three to four times a minute, with magnitudes of up to 3.3. So far, the quakes have been too small for humans to feel.
“We’ve been waiting for this for 18 years,” said Cynthia Gardner, a geologist at the Cascades Volcano Observatory in Vancouver, Wash. “We’re all just totally intrigued by it.”
Trying to gauge what the mountain is doing, researchers have set up an array of devices in the crater and on the mountain’s flanks. Aircraft have flown over the lava dome three times this week, sniffing for gases that would indicate volatile magma is rising to the surface. None was detected.
“It certainly makes us feel like we’re still looking at a relatively minor to moderate event,” Gardner said. A researcher was coming down from Alaska Thursday with a forward-looking infrared system. It will be bolted to a helicopter and flown over the lava dome to look for hot spots.
Gardner and other geologists predict that one of two things will happen: either some fresh lava will ooze out, adding to the lava dome. Or there could be a “small to moderate explosion,” sending up an ash plume that could be hundreds or thousands of feet high.
Noting the 70 percent odds, however, Gardner said “that also means there’s a one-in-three chance that nothing’s going to happen.”
The recent rumblings have sent thousands of visitors flocking to gawk at the mountain, and TV news crews have camped out, hoping to film whatever happens next. Even a moderate explosion would fling rock fragments about three miles, Gardner said. One of the volcano-watchers’ main concerns, she said, is that ash could affect aircraft engines.
Wind patterns indicate that any plume today or tomorrow would likely head for Portland and out over the Oregon Coast, said Tyree Wilde, a warning coordination meteorologist with the National Weather Service in Portland. Early next week, the winds near St. Helens will be from the north, meaning that any ash would likely blow toward central Oregon and the Columbia River Gorge.
“If it goes during the next four or five days, it’s going to go south. It will not affect Spokane whatsoever,” said Cliff Mass, a professor of atmospheric sciences at the University of Washington. And a short plume – less than 3,000 feet high – would be quickly pulled down by surface winds, he said.
That’s good news for places like Ritzville and Pullman and Spokane, where many residents vividly remember the afternoon of May 18, 1980, as a moonscape of ash and darkened skies.
Thousands of travelers were stranded in towns along the highways, unable to return home from Spokane’s Lilac Festival and conventions of federal workers and accountants. In Ritzville, 2,500 people were stranded by 5 to 7 inches of ash. Church groups fed 600 travelers camped out at the Colfax High School.
“It was like night out, even though it was mid-afternoon. The ash was real gritty and it was windy, going sideways, like in a blizzard,” said Brown. “It was like the sky was right there and you could touch it, like when there’s fog.”
Brazington, 16 at the time, was at a friend’s house for a barbecue. He thought the ash cloud was an approaching storm. He drove his mother home, the ash swirling in the roadway behind the car. Street lights came on as the sky darkened.
“It was kind of surreal, like something out of a space movie,” he said.
Rumors swirled that the ash might be acidic when mixed with water, or that it would ruin people’s lungs. Pharmacies sold out of cloth masks, and people asked local hospitals for more.
In the end, the biggest threat turned out to be to vehicles – the abrasive dust clogged air filters, scratched windshields, scarred cylinder walls and seeped into bearing grease. A day after the blast, customers lined up six deep at a Checker Auto Parts shop in Spokane, buying oil and air filters. Six Spokane city buses burned up their engines within two days, their oil fouled with grit.
“The skies were all black, and it stayed that way,” said Martha Kiilsgaard of Spokane. “It was very traumatic, like Chicken Little. The sky was falling, the sky was falling.”
She wore surgical masks for days, as she and her neighbors got out shovels and cleaned up the ash in their neighborhood.
“Everybody got out and did their bit and cleaned up, and it was an amazing amount of ash,” Kiilsgaard said. “And for years afterward, you could see it along the edges of the highway.”