A swarm of small earthquakes hit near Mount St. Helens in Washington state, early Wednesday morning on Jan. 3.
Residents reported that they felt the tremors of at least 15 earthquakes during the night. The tremors were experienced as far away as Portland and Tacoma, some 50 miles away, reported KIRO 7.
The strongest quake was a magnitude 3.9 which hit about 23 miles south-southeast of Morton at 12:30 a.m. and again just after 8:30 a.m. The second largest quake was a magnitude 2.7 which hit at 8:39 a.m., according to the USGS.
— PNSN (@PNSN1) January 3, 2018
Seismologists at the University of Washington are working on an early warning system that could send an alert about 7 to 10 seconds before the tremors begin.
“The trains running, the cars, the airplanes landing, there are a lot of things you can do with just a few seconds of warning,” seismologist John Vidale told KIRO 7.
Earthquakes are common near Mount St Helens. Seismologists said they log about 17 earthquakes a month on average in the area and tracked more 80 quakes in the past month, reported the news station.
Mount St. Helens is an active volcano with a conical peak. It last erupted in 2008, according to USGS.