Mount Rainier is not venting or showing any signs of abnormal behavior, Mount Rainier National Park Service geologist Scott Beason clarified after a tweet early Wednesday caused a stir by claiming the mountain might be venting.
In the tweet posted by a KOMO meteorologist that was widely shared, a video showed a slim cloud wafting over the mountain’s highest ridge.
“It’s a lenticular cloud,” Beason said. This type of cloud forms when air moves up and over a mountain.
“It’s just a cloud,” he said. “Completely normal.”
Lenticular clouds are often formed when moist air is pushed up and over the top of a mountain, forming its disc shape, NPS said in a statement. In Wednesday’s case, it was likely related to a passing water front.
The U.S. Geological Survey says there’s no cause for concern, adding volcanologists are at the volcano this week, installing monitoring equipment.
Although Mount Rainier has not produced a significant eruption in the past 500 years, according to USGS, it remains among the most dangerous volcanic mountains in the U.S. along with its Cascade Range sister Mount St. Helens.
Every year hundreds of earthquakes are detected at or near Rainier. While the mountain is an active volcano, the monitoring system in place will provide days if not weeks of warning should there be an impending eruption.
USGS is in the process of developing and implementing a system to better detect lahars — mud or debris flow that can form during heavy rainfall, snowmelt or landslides — which pose a threat to park visitors, employees and nearby residents.
NPS said Wednesday’s stir comes at the start of September’s Preparedness Month, calling it a “good opportunity to think about how you can prepare for the next event, volcanic or otherwise.”