The U.S. Geological Survey says a magnitude-6.3 aftershock has shaken the corner of British Columbia, near the boundary with Alaska, nearly two hours after a magnitude-6.2 earthquake hit the same area.
Geophysicist Amy Vaughan says it's not completely uncommon for an aftershock to be larger than the triggering quake, though normally the following quakes are smaller. She says there's been a series of aftershocks ranging from magnitudes 2 to 5.
The initial large quake hit around 4:30 a.m. Monday about 30 miles northwest of the tiny Alaska town of Mosquito Lake and about 83 miles southwest of Whitehorse, Canada.
The large aftershock struck within a few miles.
The geological survey website has recorded nearly 200 reports of people feeling the shaking.
Vaughan says the area is highly seismic and quakes of this magnitude aren't unexpected.