Washington’s Mount Adams has seen some pretty unusual activity as of late, the US Geological Survey (USGS) has announced. Rather than the usual one earthquake every two to three years, six occurred in the area in September alone.
According to a statement from the USGS, “this represents the most earthquakes located at Mount Adams in a month since monitoring began in 1982.”
The six earthquakes were between magnitude 0.9 to 2.0 and were picked up by a seismic station roughly 11 kilometers (7 miles) away from Mount Adams’ summit and others further away, although scientists have been unable to determine the exact depths and locations of the quakes.
We know what you’re thinking – don’t earthquakes precede volcanic eruptions? They can do, but in this case, the USGS has said that current level of earthquake activity isn’t cause for concern. Mount Adams is ranked as a “high-threat” volcano (which considers previous eruptions and how an eruption might affect populations) but it’s also a pretty quiet one – the last time it erupted was between 3,800 to 7,600 years ago.
Not only that, but none of the earthquakes have been strong enough to be felt at the surface, nor has there been any of the other typical signs of an impending eruption.
“We don’t have a dedicated gas sensing station there,” Jon Major, scientist in charge with the U.S. Geological Survey in Vancouver, told Oregon Public Broadcasting (OPB). “But there’s no indication right now that the volcano seems to be degassing in any way.” Nor has satellite imagery shown any ground deformation.
That being said, it’s still not entirely clear why the uptick in earthquakes has happened.
“The volcanoes in the Cascades talk to us all the time. Mount Adams generally is fairly quiet,” said Major. “This time, it’s decided to perk up a little bit and talk to us a little bit more. Exactly why it’s talking to us, we don’t know for sure.”
“One of our challenges is that there’s only one seismic station within about seven miles of the volcano. So it makes it really difficult to get very accurate locations and depths.”
To get a better idea of what’s going on, the Cascades Volcano Observatory has gained permission from the US Forest Service to place temporary seismic stations in the area. The real-time data from those stations will be sent to CVO and the Pacific Northwest Seismic Network (PNSN), whose job it’ll be to decipher it.
“This will improve our ability to locate smaller earthquakes with more certainty and assist in understanding the cause of these earthquakes,” said the USGS in its statement. “The results of our findings will determine if any additional actions are needed.”
