Earthquakes, there and here. – now with extra nuclear reality check

As a geoscientist and someone who works in Richmond, I am hyperaware of the situation in Japan. I was at the curling rink at midnight last Thursday when the news came on the TV. The initial pictures of tsunami waves of debris flowing over farmlands and the shock of seeing entire oil refineries going up in flames was ultimately too harrowing to watch. I had to turn it off and go to bed. The horror on the ground was too real. Roland Emmerlich be damned.

I am in no way an “earthquake expert”, my geology training is more sedimentology and tectonics, with some ichnology thrown in and a bunch of hydrogeology experience. However, during my schooling, I was lucky enough to learn about natural hazards from a couple of the people you have seen and heard on TV and the radio in the last few days (such as John Clague at SFU, who is the go-to academic on this stuff in Vancouver, and was a very busy guy last weekend). I also had seismic course work both theoretical at SFU, and more applied at the University of Hawaii-Hilo, so I would consider myself a well informed non-expert with quite a but of related background. For what that is worth.

An event like the one in Japan will not hit Vancouver in the same way it hit Sendai. The earthquake at Sendai was a very large megathrust , one of the largest quakes ever recorded (currently the USGS has it rated at magnitude 9.0), which occurred at the very shallow depth of 10km, only 100km from the shoreline. On every single scale, that is pretty much the worst case scenario.

We do get “megathrust” quakes off the west coast of BC, and some may even hit this magnitude, but Vancouver (and even Victoria) is not like Sendai. First off, the major thrust fault plate boundary off of Vancouver Island is more than 300km from Vancouver, and more than 200km from Victoria, with the bulk of the Olympic Peninsula and Vancouver Island in the way. Also, there are up to two kilometres of soft Quaternary sediments draped over the subduction zone here, which may soften the blow a bit.

That said, a megathrust will be a bad day here in Vancouver (think magnitude 6.5 quake-type shaking, but lasting for several minutes: up to 15!), but the tsunami risk to Vancouver is relatively small (with a caveat below). The west coast of Vancouver Island will not get off so easy: Tofino, Bamfield, Port Alberni: these places stand a pretty good chance of being wiped out completely. The only real good news for them is that these events are very uncommon, probably about once every 500 to 700 years, so odds are it will not happen in our lifetimes.

Probably a much higher direct risk to Greater Vancouver is presented by much smaller “crustal” earthquakes that may occur very close to the City. These quakes are usually shallow, and if close enough, can cause major damage, although tsunamis are unlikely (with that caveat below). There are unlikely to be much higher than magnitude 7 or 7.2, but the proximity is the issue. These can happen anywhere between Hope and Sooke. This is the difference between Kobe, where most of the destruction was caused by shaking and fire, and Sendai, where most of the damage was by tsunami. Locally, this type of quake is much more likely, and probably has a recurrence interval of less than 100 years in our geographic region.

Oh, can we stop saying “Richter Scale”? No-one has used the Richter Scale for about 20 years. It is the Moment Magnitude Scale now, the difference is small, but quite signficant scientifically.

The tsunami caveat I have to include is that there could be a serious secondary tsunami, caused by a major landslide on the pacific coast (say, Sea-to-Sky area?) displacing a bunch of sea water, or even worse, a major collapse of the unconsolidated sediments off the west end of the Fraser Delta, which could hit the Gulf Islands with a serious tsunami, only to have to reflected back and hit Vancouver proper. Again, this is unlikely, but would be a bad day for everyone involved.

Which brings us to Richmond. I cannot comment for the City, nothing I say here is on behalf of the City. My job in the City is related to water quality and pollution prevention, I am not in the Engineering department, so I am not really in touch with those who do the earthquake planning. The only things I know about earthquake impacts in Richmond is from reading the City’s website on the issue, and a little bit of earthquake info I gained from my own personal research. None of this is official folks, it is just my personal, relatively uninformed position.

However, buildings and dikes are built to the 1:475 standard, which means the intensity expected once every 475 years, so essentially the worst of the “local crustal” quakes anticipated. Some critical infrastructure is built to higher standards yet. Legends of the entire Lulu Island “liquefying” are rather exaggerated. There will be local liquefaction of soils, probably resulting in some road and building damage and maybe some utility failures, but not the widespread destruction some would have you believe. Modern buildings are built with Liquefaction in mind, including piles, rafted foundations, stone columns… engineers, for all I hassle them, do good work.

The dykes, for the most part, should also be fine. Minor slumping in some of the older parts of the dykes is possible, but the internal drainage system of the Island (ditches, sewers, and pumps) can deal with that. Remember, most of Richmond I actually above sea level, unless there is a major freshet on the Fraser and an exceptionally high tide at the exact same time as the earthquake, widespread flooding is extremely unlikely even in the event of a major quake.

If anyone is really concerned about an acknowledged weak link in the Earthquake protection system, maybe ask the Provincial Governement where they are in those School upgrades.

Ask any Emergency Management expert in the province and they will tell you the #1 thing you can do to protect yourself from the inevitable earthquake is to be prepared. Have a 72-hour survival kit , because you shouldn’t anticipate getting any help in the first few days after an event. Another emergency kit (water, food, blanket) for your car, and one for your workplace will give you that extra protection, as you don’t know where you will be when it happens. Finally, plan ahead with your family and loved ones to agree to a place to reunite after the event, as you may not have phones to get in touch. The more eventualities you plan for, the more secure you and your family will be when (not if) the earthquake happens.

One interesting science side of this event was the pattern of earthquakes leading up to the big thrust that caused this disaster. In the days leading up to March 11th, there were several dozen “pre-shocks” of significant size in the area of the main earthquake, even up to magnitude 6.0. The Japanese lead the world in earthquake research (all due respect to the USGS), and this pre-quake pattern will be studied to death. There is hope we will learn more about the pre-cursors for this type of quake. A day’s warning, even 6 hours warning, would mean everything to the people of Tofino or Port Alberni. Compared to the hour or so warning Sendai had between the shaking and the tsunami, it could save thousands of life.

Not that Canada is slacking on this reaserch. The Neptune Project includes a plan to wire the entire Juan de Fuca plate, from the Pacific plate to the subduction zone, with sensitive seismometers to understand the changing stress regime of the plate. This is pretty cool, cutting edge stuff, no less remarkable or technically challenging that putting a probe in orbit around Mercury. It won’t get as much press, or course, unless it actually predicts the Megathrust and saves lives.

Update: as for the nuclear plant issue, the good sciency types at have made this cool chart up to give you an idea what the actual radiation risk is. Chort form: way less relevant than the tens oft housands killed in the tsunami, or the hundresd of thousands now homeless in Japan. Click to make readable.

3 comments on “Earthquakes, there and here. – now with extra nuclear reality check

  1. I disagree with your assessment of the integrity of Lulu islands dykes and pump stations. In the event of a major quake, power will most certainly be disrupted, making the pump stations useless. It only takes a mild windstorm every year to prove the electrical infrastructure is poor. As for the dykes construction standards, I find it the notion preposterous that the dykes are built to withstand a 1:475 year occurrence. You might want to take note that the dyking system failed in 1948, and the cause was not a quake.

  2. And you are free to disagree, I am not involved in Dike design or maintenance, and am not trained to “assess” the integrity of dikes. I can only go by what I know from the public info provided by the City and the Provincial Diking Authority.

    I will mention that power interruption can be (and is) managed by emergency power backup systems, and the diking system has been significantly upgraded since 1948, including much more stringent maintenance and inspection regimes. I’m not sure what part of the BC Building Code you find “preposterous”, but the Provincial Diking Authority, and the Association of Professional Engineers and Geoscientists of BC seem to think it useful.

  3. Considering the ongoing leaky condo saga, the athletes village at false creek, the units in whistler with mold and excessive hydro bills, I consider the entire BC building code to be preposterous.

    APEGBC is BC’s biggest joke calling themselves professionals, when you can buy an engineer stamp for just about anything these days.

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