The U.S. Geological Survey says a magnitude 6.2 earthquake off the west coast of Canada on Monday night is an aftershock of the magnitude 7.7 quake that struck Saturday night.
A geophysicist says the agency had no immediate reports that the latest quake caused any significant damage or was widely felt.
The National Weather Service West Coast and Alaska Tsunami Warning Center said the Monday night quake was not expected to generate a tsunami.
USGS geophysicist Susan Hoover in Golden, Colorado, says an even larger aftershock -- a magnitude 6.3 quake -- was recorded on Sunday in the same general area off British Columbia's Queen Charlotte Islands. Since the 7.7 quake, Hoover says nearly 80 quakes registering magnitude 4.0 or higher have been recorded in the area.