The largest quake was relatively shallow, at about 6 miles, and it struck about 149 miles west of Tofino, B.C. Deeper earthquakes can be felt further away from where they occur, which explains why few people in the Northwest felt Sunday's tremors, said Don Blakeman, a geophysicist with the U.S. Geological Survey who is based in Golden, Colorado.
A trio of strong earthquakes struck off the Canadian coast near Vancouver Island Sunday night, the biggest of which was 6.8 magnitude.
The first one struck at a depth of 21 miles (33 km) about 117 miles (190 km) southwest of Port Hardy, a town on the northeast end of Vancouver island, while the second struck 135 miles (218 km) southwest of Port Hardy. There were reports of light shaking, but damage or a tsunami was not expected.
The first-of-their-kind warning sensors developed by Ocean Networks Canada are installed along the Cascadia subduction zone and when fully operating next March will be able to estimate location and magnitude of a megathrust natural disaster.
A series of three aftershocks measured between magnitude-4.3 and magnitude-4.9 followed the initial three earthquakes as well.
Map locating the quake off the western coast of Canada. Vaughan says the quakes were felt onshore.
Three powerful earthquakes hit the Canadian coastline off British Columbia on October 21, 2018.
The Ring of Fire lies in a horseshoe shape in the Pacific Ocean, stretching from New Zealand to Chile and including the Asian and American coasts.
The second quake of the night was the largest in BC since the magnitude 7.8 that hit on October 27, 2912 in Haida Gwaii. About 90 percent of the world's earthquakes are registered in the region.