If you live near Oak Bay Marina or the residential area inland past Windsor Park and down towards McNeill Bay, you are in a tsunami danger zone. You may think you’re safe when you’re further inland, but it’s all in the bosom of the earth. If a major earthquake strikes and sets off waves, seawater and debris could rush along a narrow strip above Newport Avenue, Transit Road and Central Avenue, flooding homes and endangering hundreds of lives. Oak Bay residents are not alone. New modeling and an interactive tsunami portal unveiled by the province and the Capital Regional District show most of the region’s coastlines will become danger zones and some low-lying areas from the coast and extending inland – from Port Renfrew to Sidney – are at risk from the tsunami waters. Neighborhoods around Ross Bay in Victoria could be under water and areas around Sydney could see waves reaching the Pat Bay Highway. In Sooke, Port Renfrew and the Jordan River, waters could be pushed far inland via waterways. John Cassidy, an earthquake seismologist with Natural Resources Canada and the Geological Survey of Canada based in Sydney, said the new portal – PrepareYourself.ca – is a great tool for people to determine if they live, work or visit a danger zone for a tsunami. “You can enter your own address and place of work, your children’s school, any of your usual routes and see where you might be vulnerable in a tsunami,” Cassidy said. The CRD said the region has a “one in three chance of a catastrophic earthquake” in the next 50 years. While during previous tsunami warnings people have jumped in their cars and headed for Mount Douglas or Malahat, the general advice is this: If you live in a non-tsunami risk area, it’s best to stay in their position and keep the roads clear for others in danger zones and emergency vehicles. The CRD says the area is a tsunami hazard area from several potential sources, including the Cascade Subduction Zone, the Alaska-Aleutian Subduction Zone and local shallow faults in the earth’s crust. However, the portal shows that the majority of the region’s coastline is elevated with limited tsunami risk, and the majority of the region is at little or no teletsunami (distant tsunami) risk. The main tsunami risk in the capital region is from a “sensible earthquake”. These are the immersion vibrators nearby, when the chandeliers swing and objects fall from the shelves. In these cases, residents in a danger zone should get out immediately after the shaking stops. Those outside the danger zone should stay put and be ready to help family and friends who need shelter. The CRD urges people who live and work in tsunami risk zones to practice evacuation routes by walking or cycling with family, friends or colleagues. Most will not have to travel far to reach safety. They are also encouraged to prepare a home emergency plan and gather supplies to make an emergency kit at home and bags to take home. Earthquakes that cause tsunamis typically involve vertical plate movement in a strong subduction earthquake, said Cassidy, who gave the example of the wave created when you lift a sheet of plywood into a swimming pool. But he said they can also be caused by underwater landslides. The largest recorded earthquake on Vancouver Island—Canada’s largest onshore earthquake yet—occurred on the morning of June 23, 1946, when a magnitude 7.3 earthquake centered on the Forbidden Plateau west of Courtenay and Campbell River damaged buildings, knocked down chimneys and sent up chimneys. the Straits of Georgia, overturned a boat and drowned its operator. It was felt as far away as Portland, Oregon, and caused significant damage in Cumberland, Union Bay, Courtenay, Comox, Port Alberni, and Powell River, on the east side of the strait. Then, on the night of March 27, 1964, tsunami waves generated by an earthquake in Anchorage, Alaska traveled up the Alberni Inlet, sweeping away some homes and damaging others. Depending on the size and location of the quake, Cassidy said people won’t have much time to move to safety if a tsunami hits the capital region. “If there’s a very strong shake from a closer pass, that’s a shorter period of time,” he said. A 7.7-magnitude earthquake in Haida Gwaii on October 28, 2012, generated tsunamis that generated waves of three to five meters that extended into inlets and on land along 37 kilometers of coastline. Although there were no witnesses to the event and damage to human structures was minimal because it was so remote, investigators found dead fish, driftwood logs and seaweed “dozens of meters” from shore. Pieces of algae on tree branches indicate minimum flow depths of up to 2.2 meters above ground, according to the Geological Survey of Canada and Fisheries and Oceans Canada. At some forest sites, there was evidence of large, unexpected logs that were displaced, overturned or rotated by the tsunami flows. A report said a similar summer tsunami would endanger the lives of kayakers, boaters and creek campers. The tsunami information portal was created by GeoBC — a provincial government agency — using a coastal inundation modeling and mapping report developed by Associated Engineering, DHI and Westmar Advisors with funding from the federal and provincial National Disaster Mitigation Program. The portal is currently only offered in CRD, but GeoBC may expand it in the future. [email protected]
