Something people often don't talk about is a under water landslide of the Fraser river delta out in the Georgia straight. It can slide at any point in time, however during a major earthquake the odds of it sliding go up astronomically. The tsunami produced would dwarf anything a subduction earthquake could produce, it could be up to a 100 meters in height depending on the volume of built up sediment that slides. The main force of the wave would be directed at the gulf islands and pretty much wipe them out, much of the force would reflect back across the straight of Georgia and still be in the 10's of meters in height by the time it reached Richmond, Vancouver, West Vancouver, North Vancouver. It would also travel up the Fraser River and threaten everyone probably as far as Hope depending on the initial size of the wave.
As far as the wave that would result from the subduction quake it would take over 2 hours to reach the lower mainland, but it could still be high enough to breach the dykes around Richmond and damage anything not behind one. If we are in a high tide or a low tide obviously makes a world of a difference.
I would not like to imagine a combination of a 9+ earthquake, a large tsunami and a underwater landslide of the Fraser delta, in this case Richmond would be in serious trouble along with all other sea level communities.
*keep in mind that a 9+ subducton earthquake is also strong enough to drop the ground level by a meter or two, something that is for what ever reason often not taken in to account when measuring tsunami risks. Two things happen, A) the actual plate drops, B) soft soil compacts and water gets squeezed out of it.
If it makes you feel any better in the worst case scenario of a subduction zone earthquake generated tsunami and a large under water landslide of the Fraser delta the two waves would meet some where right around Victoria...When two waves meet they stack...mind you this is based on un scientifically looking at the modeling available and taking a guess.
Talking about tsunamis we also have the Garibaldi Lake Barrier which can also slide releasing Garibaldi lake in to the Squamish valley, once again in a major earthquake the chance of it finally giving away go up astronomically. If that were to happen Squamish would be pretty much wiped out and there would be also a damaging tsunami that would travel up Howe sound and could be several meters in height.
Anyways none of this matters, you have better odds of getting hit by a car any given day. All that matters is that you get to high ground when the ground shakes intensely for several minutes straight.
Also there is always the risk of a local earthquake beneath the lower mainland, there are some minor fault lines, and as always there are going to be fault lines we dont know about until they give. For example the fault line in Haiti was unknown until it un leased a decently sized shallow earthquake in the middle of a heavily populated area.
I live ~85 metres above ground in Victoria, should I move to higher ground if there's a big earthquake?
No. A wave would not reach those heights, if it would then consider your self extremely unlucky. I would say 20m above sea level would be good, even 10m "could" be good enough in Victoria if for what ever reason you cant get higher. That doesn't mean a wave cant reach 85m but there are no records of earthquake generated tsunamis that high, the best guess is up to 30m max based on previous records. However our records are all based on recent geological events over the past few thousand years, geologically speaking this is just a blip in time. We could always shatter the records and be witness to something that happens only every several million years, some sort of mega plate bounce and a much larger sea floor deformation then anyone could imagine and a resulting mother of all tsunamis.
Obviously unlikely though, you might as well start preparing for a meteor hitting your car.
Also a landslide generated tsunami is more localized and the height of it drops quickly, if a slide in the delta were large enough to generate a 100m tsunami it would only be a few meters by the time it reached Victoria. The largest recorded landslide tsunami was in the 50's in Alaska and generated a 524m wave, however as it was just a land slide the amount of water displaced was low compared to what happens when a entire plate lifts, so by the time that wave reached the mouth of the inlet 8 km's away it was only several meters high. Mind you a delta slide could be a much larger displacement of water then what happened in Alaska that time.
Back to the point, 85m is completely fine...grab some binoculars.
/rant
Last edited by 0123456789*: 11-13-2012 at 03:49 AM.
No. A wave would not reach those heights, if it would then consider your self extremely unlucky. I would say 20m above sea level would be good, even 10m "could" be good enough in Victoria if for what ever reason you cant get higher. That doesn't mean a wave cant reach 85m but there are no records of earthquake generated tsunamis that high, the best guess is up to 30m max based on previous records. However our records are all based on recent geological events over the past few thousand years, geologically speaking this is just a blip in time. We could always shatter the records and be witness to something that happens only every several million years, some sort of mega plate bounce and a much larger sea floor deformation then anyone could imagine and a resulting mother of all tsunamis.
Obviously unlikely though, you might as well start preparing for a meteor hitting your car.
Also a landslide generated tsunami is more localized and the height of it drops quickly, if a slide in the delta were large enough to generate a 100m tsunami it would only be a few meters by the time it reached Victoria. The largest recorded landslide tsunami was in the 50's in Alaska and generated a 524m wave, however as it was just a land slide the amount of water displaced was low compared to what happens when a entire plate lifts, so by the time that wave reached the mouth of the inlet 8 km's away it was only several meters high. Mind you a delta slide could be a much larger displacement of water then what happened in Alaska that time.
Back to the point, 85m is completely fine...grab some binoculars.
Professor Frkinator does the town of Harrison Hot Springs have to worry about a Mega Tsunami in the event of a 9.0+? Could part of Mt.Breakenridge crumble off?
If it makes you feel any better in the worst case scenario of a subduction zone earthquake generated tsunami and a large under water landslide of the Fraser delta the two waves would meet some where right around Victoria...When two waves meet they stack...mind you this is based on un scientifically looking at the modeling available and taking a guess.
Talking about tsunamis we also have the Garibaldi Lake Barrier which can also slide releasing Garibaldi lake in to the Squamish valley, once again in a major earthquake the chance of it finally giving away go up astronomically. If that were to happen Squamish would be pretty much wiped out and there would be also a damaging tsunami that would travel up Howe sound and could be several meters in height.
Anyways none of this matters, you have better odds of getting hit by a car any given day. All that matters is that you get to high ground when the ground shakes intensely for several minutes straight.
Also there is always the risk of a local earthquake beneath the lower mainland, there are some minor fault lines, and as always there are going to be fault lines we dont know about until they give. For example the fault line in Haiti was unknown until it un leased a decently sized shallow earthquake in the middle of a heavily populated area.
What happens when two waves collide?
Out of these cities can you rank which would be at most risk of destruction(liquefaction, tsunami, etc)
Vancouver
West Vancouver
North Vancouver
Richmond
Burnaby
Delta
Surrey
Abbotsford
Coquitlem
Langley
Delta
Cloverdale
New Westminster
White Rock
Out of these cities can you rank which would be at most risk of destruction(liquefaction, tsunami, etc)
Vancouver
West Vancouver
North Vancouver Richmond (Underwater)
Burnaby Delta (Underwater)
Surrey
Abbotsford
Coquitlem
Langley
Cloverdale New Westminster (Half of it under water)
White Rock
Would be completely wiped out in the event of a worst case scenario 9+.
North Delta too? Most of it is on high ground, I think.
To put it simply, all of Delta is made of "soft" rock. Delta, in a 9.0 earthquake, would literally breakdown and liquefy (not instantly, so don't worry). This of course will vary from area to area in Delta.
It is a scary thought, but it is one of the main reasons for low housing prices in the Delta.
To put it simply, all of Delta is made of "soft" rock. Delta, in a 9.0 earthquake, would literally breakdown and liquefy (not instantly, so don't worry). This of course will vary from area to area in Delta.
It is a scary thought, but it is one of the main reasons for low housing prices in the Delta.
Someone please correct me if I'm wrong.
One of the main reasons for low housing prices? WTH?
