VICTORIA B.C.(np) Residents ignorant to obvious hazards.
Residents of Victoria British Columbia should "attempt to remove or upgrade dangerous structures," says seismologist Martin Bailey, of the Natural Interpretive Center for Earthquakes.(N.I.C.E.) "The hazards are well known to science," says Bailey, while the public is mostly ignorant of the dangers here. "We have a long documented history of major recurring earthquakes of a magnitude that could devastate coastal communities and cost tens of billions in damage. The hazard to human life from earthquakes lies not with the shaking from the quake itself, but the effects of 'gravity caused damage' in the effected regions. Gravity causes poorly designed buildings such as brick and unreinforced masonry to lose strength and succumb to gravity in a collapse. Tsunamis are another cause of damage and death along the coast and the cause is the sea floor changing elevation rapidly causing a tsunami wave, as sea level tries to restore itself. Once again, a gravity related killer."
The hazard exists off the coast for a 9 magnitude event which has a recurrence period of 200-500 years average. The last event was 301 years ago, Jan. 26 1700, and the quake destroyed villages near the sea, Pacific wide, the first nation Pachena village on the west coast of Vancouver Island having no survivors.Eastern Japan villages on the sea were also heavily damaged by the Pacific wide Tsunami.(Harbour Wave-in Japanese)
Another hazard lies in the risk of a smaller but locally devastating earthquake measuring between 6.5 and 7.5 magnitude occuring under Seattle or near Vancouver. These (called intraslab) events occur fairly consistently with recurrence from 20-40 years maximum. The last large event near Seattle was 1965 in Olympia which did serious damage to older brick structures. Economic cost to Vancouver should a 6.5 strike the Gulf Islands/ San Juan area would be 15 Billion Dollars, and an estimated 3000+ deaths, according to the Provincial Emergency Program statistics. The hazard that exists for a damaging quake exists for a larger earthquake than 6.5 is overdue statistically, and could be from 6.5-7.5 magnitude. 7.5 magnitude is 33 times stronger in energy release than a 6.5m. 8.5m is 1000 times stronger than 6.5m.
Ways that building owners can lesson the hazard to their particular hazards are to check for unnecessary ornamentation on the edge of rooftops which many older style buildings have. Remove these heavy ornaments permanently or replace with lighter materials such as wood or fiberglass.Remove, replace or lower false store fronts, a hazard for collapse during a quake. Check out the damage to similar buildings caused by earthquakes in other areas, and consider if you really want to own one. Pressure the local Heritage comittee to consider replacement of some dangerous structures with new ones that follow the same architecture style but with as the others on the block but with modern improvements. Look up and see what might come down...
In every case of earthquakes striking where there are brick buildings, almost all major damage has been to the older unreinforced masonry buildings. Victoria was built the same time as San Francisco, with same plans, same architecture, and same earthquake hazard (~7-8m hazard). We have been fortunate enough to not have had a large local event-YET.
Residents wishing to find hazard preparedness information can check out Natural Resources Canada, or the Provincial Emergency Program online for earthquake preparedness information.
Above all, learn the risks and how to be properly prepared for the inevitable. History shows us what to expect.