BC-Japan Tsunamis an Old Story

Posted by Howard on Mar 13, 2011 - 6 comments

The devastating March 10 earthquake and tsnumai near Sendai Japan has special meaning for British Columbians, and not just because Environment Canada placed communities on BC’s outer coast under a tsunami advisory (since lifted.) As most British Columbians are aware, our province sits on the same series of faults known as the North Pacific “Ring of Fire” that caused the March 10 quake and could experience a quake of similar force any day.

Major quakes of the kind experienced in Japan, which are known as megathrust earthquakes, happen roughly every 300 years and the last one occurred off west coast of Vancouver Island on January 26, 1700. Interestingly, this was an estimated magnitude 9 quake, the same as the Sendai event, and the reason we know the exact date is because it created a huge tsunami that was recorded in Japan (nobody was keeping written records in BC at that time.) On the west coast of Vancouver Island it deposited a blanket of sea sand on top of forest soils considerable distances inland from the shoreline.

The largest tsunami recorded during historical times on the BC coast, created by an Eathquake off southern Alaska, swept up Alberni Inlet on the night of 27–28 Mar 1964 and crashed into Port Alberni, causing $10 million worth of property damage. Other waves from the same earthquake killed 122 people in Alaska, California and Oregon. A Pacific Tsunami Warning System now enables 24 nations, including Canada, to monitor wave activity. (Encyclopedia of BC, "Tsunamis.")
For more on the conditions that make BC vulnerable to earthquakes, see the Encyclopedia of British Columbia, "Physical Geography."