A small Earthquake off the northwest coast of Haida Gwaii last night (Sept 3) was felt lightly in the villages of Skidegate and Port Clements.

The 4.2 magnitude quake occurred at 8:17 p.m. just off the coast about halfway between Daajing Giids and Masset at a depth of 23 kilometres.

No tsunami threat was detected for this quake and no damages have been reported. No aftershocks were reported.

Thousands of earthquakes are detected in B.C. every year. Of these approximately 50 are felt locally. Earthquakes of this magnitude rarely cause structural damage.   

Earthquakes powerful enough to cause structural damage occur in B.C. every decade or so, according to the provincial government. 

The last significant one was October 22, 2018 off the west coast of Vancouver Island. That 6.8 magnitude trembler was preceded by a 6.6 foreshock and 6.5 aftershock west of Port Hardy, but also did not produce a tsunami or major damage.

In 2012, Haida Gwaii experienced a 7.8 magnitude shocker that caused significant damage across the archipelago. 

B.C. is susceptible to much larger and more devastating events called megathrust earthquakes because of its location along the Cascadia Subduction Zone where the oceanic Juan de Fuca Plate is colliding with continental North American Plate.

Earthquakes with magnitudes up to 9 can occur in these zones. The last one occurred on Jan. 26, 1700 based on written records of the tsunami that hit Japan and Vancouver Island First Nations' oral histories. On that date, the entire entire zone from northern Vancouver Island to northern California ruptured. 

The resulting tsunami destroyed a First Nations winter village Pachena Bay at the south end of Vancouver Island leaving no survivors.

Quakes of that magnitude happen every 200 to 800 years. 

The B.C. government recommends being prepared for earthquakes and tsunamis. A  is available from PreparedBC.