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Hawaii’s erupting volcano is still going, and now it’s a threat to passing planes, too

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The ash plume from Kilauea’s summit prompted an aviation warning

The plume of ash rising from Kilauea’s summit.
Photo: USGS

A massive plume of ash rising from Hawaii’s Kilauea volcano prompted a warning yesterday to pilots planning to fly over the area. The eruption isn’t just dangerous to people on the ground anymore. It could also bring down planes.

Kilauea has been spurting lava, molten rock, and poisonous gases from multiple massive fissures on the island of Hawaii since May 3rd. On Tuesday morning, the Halema’uma’u crater on Kilauea’s summit also began continuously gushing ash — creating a plume that rose up to 10,000 feet in the air. Rocks falling into the vent may be responsible for more intense ash spurts. But that’s not even the worst of it, the US Geological Survey warned: “At any time, activity may become more explosive, increasing the intensity of ash production and producing ballistic projectiles near the vent.”

So the Hawaiian Volcano Observatory warned pilots about the gigantic ash plume by changing the aviation color code to red, which means that an eruption hazardous to air travel is happening or could happen soon. This morning, local time, the Hawaiian Volcano Observatory announced that the color code would stay red for the time being. “It sounds a little bit alarming,” USGS volcanologist Michelle Coombs said in a video statement. But the “code red” is just a warning to aviators flying by the island. “It doesn’t mean that a really big eruption is imminent,” she says. “It’s really just characterizing that aviation situation.”

Volcanic ash is an airborne blend of crushed rocks, glass, and gases that can clog a plane’s speedometer, kill the engine, and sandblast the windows, which impacts visibility. In the 1980s, several planes nearly crashed when their engines died after flying through ash clouds.

These days, volcano observatories and volcanic ash advisory centers around the world issue color-coded warnings to the aviation industry. The warnings range from green — which means a volcano isn’t erupting — to red, which means that it is erupting or could be soon. These notices aren’t orders: in the US, the Federal Aviation Administration is in charge of telling the pilots what to do. “We’re just saying, here is the threat: here’s the ash, here’s where it’s at, here’s how it’s being distributed,” says volcanologist Kristi Wallace.

No one at the Hawaiian Volcano Observatory was available to speak on the phone before this article published. But Wallace, who works with the Alaska Volcano Observatory, says that all of the volcano observatories around the country are chipping in. “The observatories in the United States are all under the same figurative roof, we’re all one agency,” she says.

Ash from the Kilauea plume falling onto the Ka`u desert on May 15, 2018.
Ash from the Kilauea plume falling onto the Ka`u desert on May 15th, 2018.
Photo: USGS

The USGS’s volcano observatories make the call to change the color code by keeping watch over the eruption using satellite images from the National Weather Service, data collected by earthquake sensors, and footage of the volcano from webcams. “We’re using webcam information to estimate heights of ash clouds, we have instruments detecting the concentrations of ash,” Wallace says. But the height of the cloud is more important than the amount of ash in it, she adds. “If we think an ash cloud going to intersect with flight levels, then it’s an immediate color-code red.”

Volcanic eruptions that produce massive clouds of ash are more common in Alaska, where Wallace works, than in Hawaii. In Hawaii, Wallace says, the magma is so close to the volcano itself that it doesn’t build up as much pressure by the time it comes out — producing less explosive eruptions. Usually, that means less ash, too, but explosive bursts of ash do happen, when rocks fall into a vent, for example.

“The big question is, will it continue?” she says. If the crater calms down, the warning could be downgraded to “orange.” That means that an eruption is close or underway, but it isn’t likely to produce much ash. Still, as we saw yesterday, “orange” can quickly turn back to “red.” “This is a new and dynamic situation there,” Wallace says.