A Washingtonian’s Guide to Living Among Volcanoes


Washington residents watched the dangers of ignorance in real time this week when a news video showing *Something* floating up Mount Rainier from Seattle’s vantage point sent social media into a brief tailspin. A journalist describes the video as showing a “ventilation”, implying that something unusual or even dangerous was going on. As panic spread online, experts tried to clarify that no breakdown or anything else scary was happening. Instead, the phenomenon was simply a very normal, very benign cloud.

Understanding our mountains better and knowing what to do when legitimate concerns arise can help us manage the stresses of living near volcanoes.

“Emergencies come in all kinds, and you never know when they’re going to happen. And so if nothing else, maybe that puts a little bit of emergency preparedness thinking on people’s minds,” said lead scientist Dr Jon Major at the Cascades Volcano Observatory of the US Geological Survey, who watched the social media panic unfold from his office near Mount St. Helens, another volcano in the Cascade Range that erupted in 1980.

Crosscut spoke to volcano experts like Major to gather legit volcanic warning signs and tips on how to live well in a land of natural disasters. Bottom line: don’t let the fear of a very rare eruption eat away at you – in a macabre silver lining, a volcanic eruption isn’t even the most likely natural disaster you’ll encounter as a northwester of the Pacific!

What was really going on in Mount Rainier?

Don’t blame yourself for being sucked into the whirlwind of social media. Even experts like Major had to do some research to confirm that the white wisp over Mount Rainier wasn’t a big deal. At first he thought it might be smoke from a wildfire near Packwood.

But when he saw the video himself, he did a double take. “I mean, sure, from that vantage point, it most definitely looked like a smoking plume…emanating from near the top of the volcano,” Major said.

Then he and a seismologist looked to see if the seismic instrumentation array at Mount Rainier had registered no movement similar to an earthquake: nothing to do. This is essential because when a vent opens in a volcano the rock has to be broken and this generates earthquakes. No earthquake means no eruption.

There was absolutely no indication that an explosion, venting or anything strange was happening, according to Major. His team called National Park Service colleagues in Mount Rainier to confirm twice that nothing was working.

When they began to piece together the seismology and eyewitness reports with webcam images of the mountain taken from multiple directions, they concluded cloud formation was the explanation.

When warm, moist air escapes through fractured bedrock or arrives in air currents from elsewhere, it can circulate at the top of the mountain. Under the right atmospheric conditions, this warm, humid air can condense into lenticular clouds, Major said. These clouds usually look like mushroom caps, but they’re so reminiscent of UFOs that they are likely to trigger panicked phone calls to the authorities.

For some reason, Major said, instead of a mushroom cap above the summit, this cloud condensed into a very localized area on the upper western side of the volcano known as Liberty cap. “From Seattle’s perspective, it looks a lot like a smoking vent,” he said. “If all I had to do was this video, I would have had a hard time saying anything unusual wasn’t happening.”

People in the Pacific Northwest have previously mistaken clouds and steam for signs of eruptions. Brian Terbush, earthquake/volcano program coordinator for the Washington State Division of Emergency Management, said people sometimes post about the Mount Baker steam plume. It’s “almost always on,” he said, but we can only see it well in cold, calm weather. Venting is not generally seen on other volcanoes in the region, he said.

What is ventilation, anyway?

For some people, their mental reference for “ventilation” is vigorous emissions of gas and ash from a vent in the ground – like what happened at Mount St. Helens in 2004. At that time, magma pushing upwards below the crater floor caused the glacier and its dome above to fracture, eventually breaking through with an explosion of steam and ash.

It’s out of the ordinary. However, Mount Rainier Is releases water vapor when glacial ice or groundwater warms and, to a lesser extent, also releases unpleasant gases dissolved in magma, such as sulfur dioxide and carbon dioxide. These escape through outlets called fumaroles (fyoo-ma-rolls). The gases contained in the magma push this molten rock, causing eruptions; and rising magma releases gases as it loses pressure on its way to a volcano’s surface.

But venting fumaroles doesn’t necessarily mean an eruption is occurring, and in the case of Mount Rainier, it’s quite common for these vents to hiss, spit gas, and otherwise announce their presence.

“Even when not erupting…the conduits where lava has traveled upward through the crust in the past are more open than they were before the eruption, so these are passages where things that don’t take up a lot of space, like steam and water, can travel freely,” Terbush said.

Scientists monitor this breakdown as part of eruption monitoring. If they begin to detect more ventilation than normal, or changes in the temperature or composition of gases being vented, they pay more attention.

What are the most common dangers in these mountains?

In the Cascades, the most likely hazards you might see are landslides and glacier meltdowns, which are “very common” in the summer, Terbush said. These slides can kick up plumes of dust that people sometimes call blowouts. Debris flows are common in the spring and fall and can be dangerous for visitors to Mount Rainier National Park.

“It’s important to know that if you hear a loud rumbling in the park, get to higher ground, away from rivers, as quickly as possible,” Terbush said. “But all of these events are not associated with the movement of magma and are considered non-volcanic.”

What other volcanic signs are scientists watching for?

Scientists have many methods to determine if volcanoes are acting strangely. The USGS and Pacific Northwest Seismic Network work together to identify these behaviors in three main ways: gas monitoring, seismic activity and ground deformation.

One is a seismometer, which monitors earthquakes – which occur when magma breaks up rocks on its way to the surface. Scientists monitor the size of these earthquakes as well as their frequency and depth, and compare them to background levels to analyze whether magma is moving upward. For example, the seismic network run by the PNSN identified an early morning earthquake near Poulsbo on September 8, but an earthquake does not mean an eruption is imminent.

Many earthquakes either, in some cases. Some mountains, like Mount St. Helens, experience many more earthquakes per month than others, like Mount Baker. They have different “background levels” of normal activity.

If scientists notice swarms of earthquakes, it could be due to the movement of magma or tectonic movement along minor faults in the area. There was a swarm last week for a few hours at Mount Hood, where swarms occur several times a year.

But scientists are using more than one monitoring tool to confirm what is happening. Another is ground deformation, which can occur when magma pushes upward. Using GPS sensors and radar technology, scientists even monitor millimeter-scale changes on the surface. In combination with a series of earthquakes, the deformations can help scientists confirm the movement of magma, Major said.

Mount St. Helens suffered an earthquake swarms throughout the 1980s and 1990s. When scientists saw a swarm there in September 2004 for a few days, they assumed it was a similar event. But when another swarm occurred a few days later, with larger, shallower and more frequent earthquakes, the alarm bells rang for unusual seismic activity – and lo and behold, the ground deformed and the glacier cracked. “We went from typical background activity to first blast or evacuation over a period of about a week,” Major said.


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