Huge Fireball Meteor over Alaska Sets off Volcano Warning System 360 Miles Away

A huge "fireball" meteor that lit up skies across west Alaska also set off newly installed sensors for detecting volcanic activity, the U.S. Geological Survey (USGS) has said.

The event, which took place on October 15, triggered six of the sensors' alarms at a new monitoring station on the Kenai Peninsula. The sensors are built to detect low-frequency sound waves in the atmosphere during volcanic activity, but in this case they picked up waves coming from the meteor that had streaked across the sky around 360 miles away.

In a Facebook post, the USGS said the meteor also triggered an alarm at Mount Spurr—a large, active volcano that sits around 80 miles from Anchorage that last erupted in 1992. However, as other monitoring systems also picked up on the waves, "it quickly became clear that this was not activity at Mount Spur," the post said.

Scientists with the USGS Alaska Volcano Observatory worked with researchers from the University of Alaska Fairbanks Geophysical Institute to investigate the cause. They found the meteor passed over Alaska around 40 miles from the Athabaskan community of Kaltag, which sits on the Yukon River.

In a blog post for the American Geophysical Union, UAF science writer Ned Rozell said witnesses reported the fireball in regions hundreds of miles apart. One resident of Ruby described it as an "enormous ball of light in the sky," saying it was moving north to south. Another resident said it looked like "fireworks" that split into four dots.

David Fee, head of the infrasound program at UAF's Geophysical Institute and researcher with the AVO, said he believes the meteor exploded somewhere east of Kaltag. "I typically don't work on meteors, but they are often really nice infrasound sources to help better understand the performance of our networks, and I think provide valuable information on meteors and bolides themselves," he said.

Meteors are small bits of space rock that enter Earth's atmosphere. When they do, they burn up, producing a bright light that streaks across the sky. If any rock survives, it falls to Earth and becomes a meteorite. Fee said they believe the meteorite from the event probably hit the ground somewhere north of the Innoko River and that the remains will now be buried with snow.

Over a dozen meteors are thought to hit Earth's atmosphere every day. So far this year, the American Meteor Society has recorded more than 570 events where there were more than five sightings. This includes a fireball passing over California on October 23, which was reported by 81 people. Witnesses described the fireball as being almost as bright as the moon. One onlooker said it was the "most amazing" thing they had ever seen.

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Stock image representing a meteor. A fireball above Alaska set off volcano sensors during a recent event, the USGS said. iStock