“Which way to the trashcano?” visitors asked scientists as they walked through the U.S. Geological Survey’s Cascades Volcano Observatory in east Vancouver. During Saturday’s open house, it was clear which demo drew the most intrigue.
A sizable crowd gathered in the warehouse parking lot and watched as a volcanologist poured liquid nitrogen into a plastic soda bottle, screwed the cap on tight and set the bottle in a trash can of water. The liquid nitrogen, a gas, wants to expand but can’t inside the confines of the bottle.
“It’s the same principle that drives volcanic eruptions,” said volcanologist Alexa Van Eaton.
After a few seconds of anticipation … BOOM! Water and pink and red balloons shot out of the trash can.
A pair of children — eager to help with the experiment — traced a chalk outline showing how far the material dispersed. The pink balloons, filled with mostly air and water, represented lightweight pumice; the heavier red balloons filled with water represent the denser materials, known as lithics, that can shoot out of volcanoes during an eruption, said volcanologist Heather Wright.
After an eruption, volcanologists measure pumice layers to help determine how high and how far the eruption pushed materials. Debris reached Montana about 6½ hours after Mount St. Helens erupted in 1980, Wright said.
Jennifer Adams and her son sat in front to get a good view of the trashcano.
“We thought we’d check it out and geek out with the scientists,” Adams said. She was visiting Vancouver from out of town and took her 5-year-old son, who’s fascinated by volcanoes.
Learning how volcanoes work and identifying hazards is the crux of the volcano observatory, which monitors the Cascade Mountains as far north as Mount Baker near the Canadian border and as far south as Crater Lake in southern Oregon.
There hasn’t been an open house in five years, said spokeswoman Carolyn Driedger. One was scheduled for 2013 but didn’t happen due to budget restraints. Saturday gave researchers a chance to show off what they’ve been working on and the technology they use to learn more about the Cascades. It also happened to fall a couple weeks shy of May 18, the 35th anniversary of the 1980 Mount St. Helens eruption.
“As the memory of Mount St. Helens declines, we want to get the message across that this is an active volcano,” Driedger said.