SEATTLE — As Mount Kilauea unleashes a world-class show of geologic force on Hawaii’s Big Island, some Northwesterners are eyeing the Cascade Range with a new wariness.
“Mental note: Don’t live near a volcano!” one Seattleite tweeted last week, pointing out the city’s view of Mount Rainier.
@MountRainier WA itself — or its anonymous social-media avatar — also took to Twitter with a warning for May, which is Washington State Volcano Preparedness Month: “Everybody go out and buy a gallon of water, a windup radio and all of the lava-resistant clothes you can find.”
It’s an empty threat at the moment, scientists say, but a good reminder that the Pacific Northwest is home to an 800-mile chain of active volcanoes that have erupted in the recent past and will erupt again in the future.
With their towering, snow-capped peaks, the Cascade volcanoes are very different beasts from Hawaii’s low-slung, shield volcanoes, says Seth Moran, scientist-in-charge of the U.S. Geological Survey’s Cascades Volcano Observatory. They don’t erupt as often and they don’t spew out as much magma — but when they do let loose, the result can be the type of explosive blast epitomized by Mount St. Helens’ 1980 cataclysm.
Nine Cascade volcanoes have the potential to erupt in our lifetimes, Moran said. (In Washington: Mount Rainier, Mount St. Helens, Glacier Peak, Mount Baker and Mount Adams. In Oregon: Crater Lake, Mount Hood, Newberry Volcano and the Three Sisters.)
All are currently quiet, but the eruption that blew off Mount St. Helens’ top in 1980 and the dome-building eruptions that followed in 2004-08 show how quickly the giants can stir to life.
“Those two eruptions came out of nowhere, and we had about a week’s worth of earthquakes before the first explosion,” Moran said. “We’ve got nine volcanoes that really could erupt tomorrow, and we need to treat that as a serious possibility.”
The most likely scenario, though, is that any eruption will be preceded by days to weeks of seismic rumblings, ground movement and gas emissions that signal the movement of magma — and which can be detected by ongoing monitoring at all the region’s volcanoes.
“It’s our job not to be surprised,” Moran said.
Given its restless nature, geologists say, Mount St. Helens is the odds-on favorite to erupt next. But six other Cascade volcanoes have been active in the past 300 years, including steam eruptions at Glacier Peak and Mount Rainier and a 1915 blast at Mount Lassen, in California, that destroyed nearby ranches.
But the type of scenes playing out in Hawaii, with rivers of lava snaking through neighborhoods and sprouting fountains, are highly unlikely in the Pacific Northwest, Moran said. Cascade volcanos produce a thicker, more viscous type of lava than Hawaiian volcanoes, so it doesn’t run out as far. Also, very few people live on the flanks of our volcanoes.
The Cascades Volcano Observatory posts weekly status reports for the region’s volcanoes. All currently register “normal.”