The last megathrust earthquake shook the Pacific Coast in 1700, resulting in a tsunami that pushed all the way to Japan.
The Cascadia Subduction Zone along the Northwest Coast of North America is estimated to be 70 years past due for a major seismic event — and Prince Rupert residents could sleep through a tsunami warning, just as they did on Jan. 23.
The warning was issued for the B.C. coast at 2:06 a.m. after a 7.9-magnitude earthquake struck the Gulf of Alaska at 1:31 a.m. Fortunately, the quake was a “strike-slip” and not a “thrust”, which would have moved more water.
The tsunami warning prompted sirens in Metlakatla, Lax Kw’alaams, Hartley Bay and Port Edward, while the City of Prince Rupert monitored the situation and posted updates on Twitter. Many are now asking why their community doesn’t have sirens, and how they will know if there is a risk.
Air raid sirens were introduced to Prince Rupert in 1942, when the city was transformed as an army base during the Second World War. On Feb. 8, 1942, Lt. R. Thistle, the Air Intelligence Officer for the Prince Rupert Defences, wrote in his diary: “At 1500 hours the Air Raid Sirens were tested and worked satisfactory. They were not heard well in some parts of the city.”
Modern sirens, such as the ones installed in Lax Kw’alaams, ensure sirens are heard in every home across the community with multiple installments. The wail of the siren will sound remotely from either a police or fire station, and a voice will tell residents exactly what to do: “tsunami warning, evacuate to higher ground.”
In Prince Rupert, there were three sirens positioned across the city, one atop where city hall is now, which used to be a federal building, another was located on Sixth Avenue East and Donald Street, and another at Roosevelt Park.
Former mayor of Prince Rupert, Jack Mussallem, said he remembers the grey sirens in the city in the 60s and 70s as part of a National Defence program.
“When the program ended they asked the city whether or not they’d want the sirens and I believe the city, when contacted, declined and the Department of National Defence took them down,” Mussallem said.
Another system has yet to replace it.
City reevaluates its alert system
When the overnight tsunami warning was issued, the City of Prince Rupert directed people to the emergency muster station at the Recreation Complex — a building that is not fully earthquake proof.
“As the Recreation Complex is an older building, and may not be entirely earthquake proof in the event of a serious earthquake, the city has coordinated alternative muster stations with the school district,” Veronika Stewart, manager of communications at the City of Prince Rupert, said in an email.
The city is working on improving its alert system for possible future events to better notify the public of what to do, and where to go, depending on the the type of emergency.
“We’re evaluating an alert system, not necessarily a siren, but a system where we send local alerts to cell phones and land lines and potentially email, ” Stewart said following the Jan. 23 tsunami warning.
The District of Kitimat uses a messaging system called Rapid Notify where residents sign up to receive emergency messages. Emergency response vehicles also use sirens and loudspeakers to give verbal instruction in case of emergency.
Skeena MLA Ellis Ross said the emergency program took a number of years to develop. They found that the province can only help by giving information and it wasn’t fast enough.
“The bottom line for us is it’s got to be a homegrown plan…you have to cater it to your own community. Number one, the people have to know what to do, and where to go, and who will provide accurate information,” Ross said following the most recent tsunami warning.
Other politicians found the lack of consistency across the province unacceptable. Dianne Watts, BC Liberal leadership candidate, said in an email there needs to be a single source that provides consistent, accurate and up-to-date information in the event of a natural disaster.
“Moving forward, all B.C. communities, particularly those on the coast, such as Prince Rupert, need to have standardized equipment including sirens to alert residents of an impending disaster such as a tsunami,” Watts said.
Historical records state there is a four-metre evacuation zone affecting two residential areas, Beach Place and Water Street, save the odd sailor who lives on their boat in Cow Bay Marina or Rushbrook Floats.
But modern records are in the works, and the city is in the process of doing modelling and creating a tsunami hazard assessment and flood mapping data to be ready by 2019.
“When in doubt, if you feel an earthquake, the most important first step is to move to high ground — which is considered to be anything higher than the downtown core,” Stewart said.
While Prince Rupert looks to improve its tsunami alert system by exploring apps, other communities are choosing to use sirens. Klemtu is the latest First Nations community to update its tsunami warning system by installing sirens by Whelen Canada.
“They’re getting a five-cell system. Every cell has 400 watts of siren and voice communication. They have 2,000 watts of voice and siren capability for their band. On Monday [Jan. 22] they said yes, placed the order, then on Tuesday this thing happened,” said Malcolm Leslie, president for Whelen Canada.
The price tag for a five-cell system is approximately $70,000.
Leslie said the cost for the Lax Kw’alaams system, which has fewer sirens, was approximately $40,000. Lax Kw’alaams has a manual system with the siren controls in the band office. They have two people assigned to do a weekly test on the system.
“Prince Rupert itself is long and narrow. It doesn’t go too far in. We’d need maybe 5-10 cells to cover that area,” Leslie said.
For a 10-cell warning system with voice, and a five cell mass notification system with central station control, the total cost for the City of Prince Rupert would be approximately $168,540.
Port Alberni opted for nine sirens following the tsunami of March 27, 1964 when two waves, 2.44 metres and 3.05 metres, travelled 40 km up the Alberni Inlet into the town, washing away 55 homes and damaging 375. There were zero fatalities but the municipality braced itself for future events.
The same 9.2-magnitude earthquake in Alaska in 1964 triggered a 1.4-metre tsunami wave in Prince Rupert with little damage. But is Prince Rupert at risk of being hit by a massive tsunami?
Tania Lado Insua, Ocean Analytics Program Manager with Ocean Networks Canada, is currently focusing her studies on the Cascadian Subduction Zone. She said Prince Rupert could be affected by tsunamis coming from three main areas, the Alaska-Aleutian Subduction Zone, the Fairweather-Queen Charlotte fault system and the Cascadia Subduction Zone.
“There may also be risk of landslide generated tsunamis in areas close by that could have a bigger impact. This is hard to define without doing a thorough review of the area,” Insua said in an email, adding that she is currently working on simulations that would give an approximation, but the results won’t be ready until later in the year.
To put wave size in perspective, on March 11, 2011, Japan experienced seven to 10 metre tsunami waves that travelled inland as far as 10 kms.
“Previous tsunami waves give us information about the resonance of the area, this is if the shape of the coast potentially increases the size of the wave. This happens when the size of the basin is proportional to the tsunami wave length.
“Prince Rupert is not an extreme case of resonance, such as Port Alberni, for example, but without running some models it is hard to tell the exact impact that a tsunami will have. All I can tell you is that unless there is a landslide in the nearby areas, Prince Rupert will have less impact than areas such as Port Alberni and Hot Spring Cove.”
Less impact, but the risk is still there, and the case for sirens as an early warning system, as well as a text message system, could avoid residents from sleeping through the next “big one”.