Could downtown Toronto be taken out by an earthquake & tsunami one day?

[MIJ-VI]

Glacial Lake Iroquois

Two ancient shorelines in the Toronto area mark the existence of former glacial lakes. About 2 km inland from the shore a ridge known as the Iroquois Shoreline can be discerned. The old shoreline runs west-east running roughly parallel to Davenport Road just south of St. Clair Avenue West. Further east, the Scarborough Bluffs also formed part of the shoreline of the ancient lake....

street map of toronto - Google Maps

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Researchers warn of earthquake
1994-07-28 00:00:00

Researchers warn Southern Ontario may face earthquakes

WATERLOO, Ont. -- If a controversial theory put forth by a team of researchers studying seismic activity in Lake Ontario proves correct, Southern Ontario is more earthquake- prone than was previously believed.

"It's a fairly highly populated area, so it introduces an element of risk which didn't exist before in the minds of people," says Prof. Richard Thomas, head of the research team and director of the Waterloo Centre for Groundwater Research based at the University of Waterloo.

Scans of the bottom of Lake Ontario conducted during searches for downed aircraft revealed three previously undocumented features. Using that data and studies of their own, the research team identified the features as the result of tectonic activity due to a fault line.

The three features, known as pop-ups, plumose structures and dark linear patterns, are located in western Lake Ontario. A pop-up is a ridge with a crack at the top, formed when the bedrock fractures because of compressional forces in the crust. A plumose structure is several kilometres long and looks like a feather etched into the lake bottom. The dark linear patterns are believed to be due to natural gas coming up through the rocks into the bottom sediments.

Interestingly enough, says Thomas, the features all occur on the same line going through Burlington to Toronto. "In 1987 and 1988, there were two earthquakes recorded right on that line, which were about magnitude 3.5 (on the Richter scale). So there is earthquake evidence to suggest that the interpretation of these features is correct.

"This indicates a major fault structure occurring in that part of the lake. . . . What it indicates is that there is a greater likelihood of a significant earthquake taking place than was originally believed."

Earthquakes occurring in the Great Lakes region were thought to be in response to crustal rebound caused by the removal of ice from the last ice age. "Now, crustal rebound is taking place, but if you look at the pattern, it's not random," Thomas says. "The pattern would suggest that it's following a quite distinct orientation."

Additional work has revealed faulting in the south- eastern part of Lake Ontario. The scientists are coming to believe that Lake Ontario and possibly Lake Erie lie on an extension of the well-known St. Lawrence fault system.

The growing realization that fault lines could occur in the middle of a continent has led to a new science called intra-plate tectonics. "These are (earthquake) areas occurring in the middle of plates. The traditional belief was that all activity occurred on (continental) plate margins, where they collide or are in motion. They (mid- continental faults) are basically resulting from the various pressures induced on the plate because they're in motion, and these are lines of weakness which are currently being re- activated."

More work is needed before the team is completely satisfied that its theory is correct, Thomas adds. "What we need to do is do a lot more investigative work, using marine geo-physical systems to map the structures and make sure that they follow the concepts that we currently have."

In the scientific domain, this has been battled over since 1987, he says. "The actual release to the public, and the public debate, has only just begun. And not all scientists subscribe to this. It's still in the process of being verified. What they say is that Southern Ontario is in a stable area. It's in the middle of a continent, and it's stable, that the minor earthquakes are related to crustal rebound from removal of the ice masses, and that the Great Lakes originated by ice scrapping. The hypothesis challenges that paradigm totally.

"If you accept that it (the increased possibility of earthquakes) exists, it gives you a whole new way of looking at things."

If the theory is true, Thomas says, it may have some ramifications in the location of waste disposal sites and building construction.

He says this should be getting a bit more attention from scientists than it is receiving at present, because of the possibility of a large earthquake re-occurring in the area. The features indicate that the Great Lakes region experienced a large earthquake at some time in the past. But without knowing the "return frequency," scientists are in the dark about when it will recur.

"The return frequency is a statistical evaluation of how often an earthquake at one location will return with a certain level of magnitude," Thomas explains. "What is the return frequency of the San Francisco earthquake? It hasn't come back yet. But it will happen again. What it means is that stress is building up and releasing. Large earthquakes have a long return frequency. And the trouble is we don't know when the last large earthquake occurred in this area (the Great Lakes)."

*Cue the gleeful posts from western Canadians*



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Canada
Earthquakes of the last 30 days

[squarepeg]

Possibly, but I think the time required for a glacier to form and then suddenly melt would probably give adequate warning.

[JimB52]

Originally Posted by squarepeg

Possibly, but I think the time required for a glacier to form and then suddenly melt would probably give adequate warning.

I guess somebody never saw 'The Day After Tomorrow"

[polemouse]

Yes! And it is going to suck!

[Ripper]

well, first off it would have to be a rather large earthquake. IIRC, the most powerful one recorded in WNY was a 5.2. Also, I dont see how Ontario is large enough to ripple more than a couple feet when it hits shore, baring a sudden crack in the plate directly under it that causes Toronto to drop in elevation suddenly such as the massive quake/wave in Alaska.

[Lady Kayri]

Well, let's remember the nasty quake they had just south of Chicago 150+ years ago - in places, the Mississippi actually ran backwards... Sorry, I'm not home, so I can't look the info as to name, exact date, etc. up, but I think it's been estimated it was somewhere around 7.0 - 7.5 in strength. At the time it happened, there weren't a lot of people living in the area it occurred in, so it didn't do a lot of damage. Today would be a much different story...

[JimB52]

You must mean the New Madrid Earthquakes of 1811. Supposedly felt 1,000 miles away.

1812 New Madrid earthquake - Wikipedia, the free encyclopedia

[squarepeg]

Originally Posted by JimB52

I guess somebody never saw 'The Day After Tomorrow"

No problem. I took three flying lessons, so if anybody needs a co-pilot for a Russian transport plane, I'm your huckleberry.

[elgecko]

Originally Posted by squarepeg

Possibly, but I think the time required for a glacier to form and then suddenly melt would probably give adequate warning.

The last ice age was 10,000 years ago. In geologic time, that IS "sudden".

[warwick.hoy]

Seems like the earth is entering a very geologically active period. The main concern over here is the caldera that is Yellowstone the eruption of which will have global implications (Downtown Toronto and the rest of the eastern seaboard included).

While this is certainly natural from a geological standpoint,...the human civilization will be rocked by such events.

[elgecko]

Originally Posted by warwick.hoy

Seems like the earth is entering a very geologically active period. The main concern over here is the caldera that is Yellowstone the eruption of which will have global implications (Downtown Toronto and the rest of the eastern seaboard included).

While this is certainly natural from a geological standpoint,...the human civilization will be rocked by such events.

There are volcanic deposits in California from the last Yellowstone event!

[Richland123]

How many people can fit into the CN Tower?

[MIJ-VI]

Originally Posted by warwick.hoy

Seems like the earth is entering a very geologically active period. The main concern over here is the caldera that is Yellowstone the eruption of which will have global implications (Downtown Toronto and the rest of the eastern seaboard included).

While this is certainly natural from a geological standpoint,...the human civilization will be rocked by such events.

YouTube - Yellowstone Super Volcano Alert - History Channel Special

Taken from:

Yellowstone Supervolcano Supervolcano Yellowstone Park



Supervolcanoes Around The World

[Lady Kayri]

Yeah, New Madrid. Just think of what could happen in places like Chicago if it lets go; could be in the 7.0 to 9.0 range. They don't build to earthquake standards in Chicago or that area - it might be worse than what happened in San Fran back in the day! All those unreinforced buildings, especially the brick ones. Look at the damage caused in Calif by earthquakes since the 1970's, and remember that THOSE buildings (supposedly) WERE built in anticipation of earthquakes. And a shift on the New Madrid could well travel far enough to affect Toronto and other Canadian cities... to say nothing of tsunamis on the Great Lakes!

[iamlowsound]

Ottawa and Montreal lie on a minor fault line and there was a 5.3 there this year. I highly doubt that there could be one in Southern Ontario, but a bad one in Ottawa could do a lot of damage in this part of Ontario.

lowsound

[MIJ-VI]

List of earthquakes in Canada - Wikipedia, the free encyclopedia

[Ubersheist]

Ok... I am a geologist by trade. In fact, I'm certified by the State of California as an engineering geologist. That means that the state (which has the strictest regulations and requirements for certification in the USA) said that I am competent and knowledgeable enough about seismology to make recommendations on how to build with regards to earthquakes, and how earthquakes of various sizes and locations will affect people, where we live and the structures that we use.

First off, it is possible to have any magnitude of earthquake of any size almost anywhere. We don't know everything about what's going on underground, and the science of seismology is still really just starting to get into a more modern era. There's alot we don't understand.

That said, it's extremely unlikely that anything like a tsunami or a large-ish earthquake would ever hit Toronto. Sure, it's possible, but it's also possible that Los Angeles could get hit with a snow storm that'll leave 2 feet of snow on the ground. It's possible, but the likelyhood is so incredibly remote, that it's not worth preparing for.

As far as those stupid Discovery Channel shows go about Yellowstone being the next Pinatubo... well, that's more likely, but we'd still have ample time and warning to prepare. Those TV shows always paint an absolutely worse-case scenario that doesn't reflect reality and what might really happen if a volcano was to erupt there. They focus on the destructive forces, and the crazy graphics that rile people up. The reality is that new and reoccurring volcano systems such as the hot spot under Yellowstone just plain don't pop up suddenly. They take years. Decades, in some cases. Those dumb shows always gloss over that, and just focus on the "what if it happened tomorrow" scenarios, which are totally unrealistic. [/rant]

So please, watch all the Discovery Channel shows on volcanoes and natural disasters, and the "Day After Tomorrow" disaster movies... But please enjoy them for what they are - overly sensationalized pieces of fiction.

[Ubersheist]

Originally Posted by Lady Kayri

Yeah, New Madrid. Just think of what could happen in places like Chicago if it lets go; could be in the 7.0 to 9.0 range. They don't build to earthquake standards in Chicago or that area - it might be worse than what happened in San Fran back in the day! All those unreinforced buildings, especially the brick ones. Look at the damage caused in Calif by earthquakes since the 1970's, and remember that THOSE buildings (supposedly) WERE built in anticipation of earthquakes. And a shift on the New Madrid could well travel far enough to affect Toronto and other Canadian cities... to say nothing of tsunamis on the Great Lakes!

Ok... to address all the concerns above...

Won't happen, wouldn't ever happen, those buildings will get destroyed by other natural disasters long, long, long, long before they ever have issues with an earthquake, the New Madrid fault is VERY far away and couldn't possibly affect Chicago or anywhere near Canada, and no tsunamis will ever affect the Great Lakes.

[iamlowsound]

Originally Posted by Ubersheist

Ok... to address all the concerns above...

Won't happen, wouldn't ever happen, those buildings will get destroyed by other natural disasters long, long, long, long before they ever have issues with an earthquake, the New Madrid fault is VERY far away and couldn't possibly affect Chicago or anywhere near Canada, and no tsunamis will ever affect the Great Lakes.

Woo, knowledgeable people for the win! The great lakes are too small and too shallow to even build up enough water for a tsunami. AFAIK the only fault line in Canada that could possibly pose a problem is the one under Ottawa and the Ontario and Quebec building codes are well prepared for that.

lowsound

[Ubersheist]

Originally Posted by iamlowsound

Woo, knowledgeable people for the win! The great lakes are too small and too shallow to even build up enough water for a tsunami. AFAIK the only fault line in Canada that could possibly pose a problem is the one under Ottawa and the Ontario and Quebec building codes are well prepared for that.

lowsound

I'm really not very familiar with earthquakes in Canada in general, but here's what I do know: There are some active faults in the east in Quebec, with most (I think) near the St. Lawrence River and further to the north in the northernmost part of Quebec. I remember reading that somewhere, but I'm not very sure. I know that there's at least some potential for decent sized quakes in that general area.

The real seismic activity is in Western Canada, and they have some real potential for damage. Vancouver and Victoria are in some very seismically active areas, as far as I know. There's also active faulting scattered throughout BC and Alberta, and they extend into the Yukon and into the NW Territories.