This earthquake is likely associated with relative motion across the Queen Charlotte fault system offshore of British Columbia, Canada. Studies of tectonics in this region suggest plate motions are taken up by strike slip faulting parallel to the plate boundary, accompanied by lesser amounts of thrust motion to accommodate the oblique nature of the plate motion vector between the two plates with respect to the main plate boundary fault structure. It is not clear whether this oblique component of plate motion involves underthrusting of the western edge of the Pacific Plate beneath North America, or whether such motions are taken up on crustal faults. The October 28th earthquake is consistent with either scenario.

USGS

Global BC Facebook followers report feeling the initial quake from Prince George, Kitimat, Fraser Lake. One person noted her dog 'freaked out' before she felt a mild tremor.

Stay tuned here, Shannon. So far we've had reports of a small tsunami and no reports of damage.

A small tsunami, below 30 cm, has been detected in south-east Alaska. Tsunami warnings remain in effect for coastal BC, from north tip of Vancouver Island to Cape Decision, SE of Sitka Alaska.

Are you seeing any damage from the earthquake where you are? We're looking for any pics or video. Send to tips@globaltvbc.com or go to globaltvbc.com and join our Global Ground Force.

From the USGS' Tectonic Summary:

The October 28th, 2012 (October 27 at the location of the epicenter) M 7.7 earthquake south of Masset, Canada, occurred as a result of oblique-thrust faulting on or near the plate boundary between the Pacific and North America plates. At the location of this event, the Pacific plate moves approximately north-northwest with respect to the North America plate at a rate of approximately 50 mm/yr.

This earthquake is likely associated with relative motion across the Queen Charlotte fault system offshore of British Columbia, Canada. Studies of tectonics in this region suggest plate motions are taken up by strike slip faulting parallel to the plate boundary, accompanied by lesser amounts of thrust motion to accommodate the oblique nature of the plate motion vector between the two plates with respect to the main plate boundary fault structure. It is not clear whether this oblique component of plate motion involves underthrusting of the western edge of the Pacific Plate beneath North America, or whether such motions are taken up on crustal faults. The October 28th earthquake is consistent with either scenario.

This region of the Pacific:North America plate boundary has hosted 7 earthquakes of magnitude 6 or greater over the past 40 years – the largest of which was a M 6.6 earthquake in 2009, 80 km to the south east of the 2012 earthquake. In 1949, a M 8.1 earthquake occurred closer to the Pacific:North America plate boundary, likely as a result of strike-slip faulting, approximately 100 km northwest of the October 28th earthquake, near the northern extent of Haida Gwaii (Queen Charlotte Islands).

earthquake.usgs.gov