A massive subduction earthquake off the West Coast would kill nearly 400 people and cause more than $150-million in damages, according to a scenario that emergency planners have mapped out in a training exercise slated to take place in just over a week.
Among the fatalities would be two dozen dead in British Columbia, where a tsunami is expected to drive inland near Tofino, sweeping cars from Highway 4 between Long Beach and the picturesque resort town on the West Coast of Vancouver Island.
The scenario is detailed in a handbook for tsunami experts in the U.S. and Canada, who have for months been planning an exercise to rehearse what will happen when an earthquake on the scale of the one that shook Japan hits the West Coast of North America.
The exercise envisions a massive, magnitude 9 quake striking the Cascadia fault, just offshore from Portland, Ore., in a subduction zone where two tectonic plates are in collision.
Unlike the earthquake in Japan, the one to be simulated in the exercise known as PACIFICEX11 will unleash a tsunami that races along the coast, from California to Alaska, before sending a pulse out across the Pacific. In other words, it will be the mirror image of what happened Thursday night in Japan.
The planning handbook contains copies of the tsunami bulletins that will be issued by the West Coast/Alaska Tsunami Warning Center once the exercise gets under way on March 23.
The first bulletin, to be issued at 11 a.m., is almost identical to the one issued at 9:46 p.m. Pacific Time on Thursday, when the Tsunami Warning Centre in Palmer, Alaska, sent out warnings coast-wide following the earthquake in Japan.
“Persons in low-lying coastal areas should be alert to instructions from their local emergency officials,” it advises. “Persons in tsunami warning coast areas should move inland to higher ground. Persons in tsunami watch areas should stay alert for supplemental information.”
On Canada’s West Coast, where earthquake bulletins from California to Alaska are routine, and where tsunami alerts happen several times a year, the wording would seem familiar.
But 32 minutes later another bulletin signals to training participants that they are simulating something much worse. Somewhere under the ocean, a huge slab has surged, pushing a tsunami up the coast.
“Forecast models project that 23 ft/7 meter waves could impact along the West Coasts of British Columbia – Washington – Oregon and Northern California,” warns the bulletin. “The entire tsunami hazard zone is in danger.”
The bulletin goes on to say a tsunami nearly five metres in height hit Crescent City, Calif., destroying the main pier in the harbor and taking out 24 boats. It states that “33 people are reported missing.”
But there is worse news to come. Relying on deep-water buoys that are moored far off the coast, the Tsunami Warning Centre advises that dangerous tsunamis are being generated in Central and Southern California, Northern B.C. and Alaska.
Jack McNamara Air Field in Crescent City is flooded, the Agate Beach Golf Course and the Newport Municipal Airport are under water, and “Newport is reporting 32 people missing and presumed dead after they went down to observe the sea life on the ocean floor as the water drew out prior to the tsunami.”
Along Highway 101, in Cannon Beach, seaside homes are inundated.
At 12:35, only 90 minutes after the first warning, a tsunami strikes Tofino.
“Canadian Hwy 4 is submerged.… Three cars, with occupants, were swept off this road and into the sea. All drivers are presumed dead,” states the bulletin.
A small tsunami, under two metres in height, strikes the beaches in Vancouver. It doesn’t cause any damage, but is a reminder that even in a protected harbor, the city is at risk.
