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Old 10-27-2011, 10:00 PM
 
Location: Carrboro and Concord, NC
964 posts, read 2,051,300 times
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Quote:
Originally Posted by BayAreaHillbilly View Post
The next big New Madrid shaker is going to be a real bummer. Imagine all the non reinforced brick buildings in Memphis and St. Louis. Even places like Chicago, Cincinnati, Louisville, Little Rock, Jackson, Columbus, Indianapolis, etc, etc may be in for a rude awakening. Look at what a mere 5.8 did on the East Coast.
Yeah - on that fault it could be hundreds of years - the midcontinental faults are far less active, and then ... bang. But the 1811-1812 series of quakes - at least 3 of them were 8.0 or greater) shifted the channel of the Mississippi River 8-10 miles in places, and were felt as far away as the New England states.

The geology of that fault is kinda fascinating. It's theorized that the New Madrid and Saint Lawrence River faults are disconnected pieces of a failed rift (like the Great Rift Valley in east Africa), where North America - well over a million years ago - began to rift apart into two separate continents. The process continued to the point of creating two faults running NE-SW from Quebec to Arkansas, and then afterwards the process of rifting stopped or died for unknown reasons. The theory is that the very infrequent (200-500 year intervals, or longer even) large quakes along that fault system are essentially the process of a dying fault system 'settling,' or slowly (over millions of years) re-setting to a true state of complete inactivity.

It's also theorized that the nearly continual swarm of too-small-to-be-felt quakes that are picked up on seismographs in SE Missouri, SW Kentucky, NW Tennessee, NE Arkansas, and far S Illinois are likely diminishing aftershocks 200 years after the main event. It will be exactly 200 years mid-December.

Something similar can be seen in the Charleston, SC area - a spike in very small quakes along a line starting in Charleston and running inland, northwest for about 40 miles - swarms of small quakes in a 50 mile radius in a state that is otherwise/elsewhere seismically dead.
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Old 10-27-2011, 10:17 PM
 
Location: Northfield, MN
766 posts, read 1,857,185 times
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I'd say the one that runs straight through St. Louis. If that one ruptures, that entire city is destroyed, because all the buildings are brick, and not built to withstand large earthquakes.
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Old 10-28-2011, 12:25 AM
 
Location: where you sip the tea of the breasts of the spinsters of Utica
8,301 posts, read 12,241,351 times
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California has been spending enormous amounts of money on retrofitting, and strict codes for new buildings - I think that will help quite a lot, if there hasn't been much cheating by contractors. I don't think there will be massive loss of life.

I've been through two smallish earthquakes, none in California though I've lived here several years total (mostly not in earthquake zones). There was one in upstate New York that was about a 4.0 - I think that was in the mid 70s? which was very noticeable, but felt very different from one in Seattle that was ..... oh, I forget, maybe a 5.0. The NY one was very much like a train passing nearby, that kind of sound and shaking. The Seattle one was more swaying.

I'd say definitely that Seattle has more to worry about than the Bay Area. Lots of old buildings that were never retrofitted (though the old brick hotel I was in swayed to the point of someone screaming from it without cracking at all, I would never have expected that of such an old rigid structure).

I wonder about the tsunami from that - it's right off the coast of Washington, but Seattle would be protected somewhat by the Olympic peninsula, so it would be mainly whatever is generated in Puget Sound - which is over the subduction zone of the fault, so that would be considerable. I wonder how high up the wave could climb if it's a 9 earthquake, and how much time there would be to run before it hits?
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Old 10-29-2011, 05:52 AM
 
3,644 posts, read 9,024,722 times
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Quote:
Originally Posted by AGuyFromCleveland18 View Post
I'd say the one that runs straight through St. Louis. If that one ruptures, that entire city is destroyed, because all the buildings are brick, and not built to withstand large earthquakes.
it's actually a lot closer to Memphis, and would do a lot more damage. And Memphis has a lot of brick too


About The New Madrid Fault


GOING GLOBAL - EAST MEETS WEST - ARTICLES OF INTEREST: New Madrid fault line attack underway, 15 nuclear reactors targeted ...

thats why I need to get the hell outta here
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Old 10-30-2011, 10:44 AM
 
Location: Somewhere in Texas
5,232 posts, read 11,694,843 times
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I read somewhere (can't find it now) that the New Madrid potential quake area can cause one much worse than those in California. It had something to do with the soil/ground. Here's an example of the extent of the same magnitude of a California quake and a New Madrid. Chances are it will never happen in our life time. 1812 was almost two-hundred years ago so hopefully, it will "hold out" for another several hundred.
Attached Thumbnails
America's Most Dangerous Fault-new-madrid-fault-earthquake-zone.jpg  
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Old 10-30-2011, 09:33 PM
 
1,108 posts, read 1,977,595 times
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What about the fault in the Mariana Trench which is the deepest spot in the ocean. There are two plates with one going under the other one. What if something snaps and one of those plates rises from the ocean floor. Or is that impossible? I don't know much about it but it seems like a fragile situation down there.
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Old 10-30-2011, 10:03 PM
 
Location: where you sip the tea of the breasts of the spinsters of Utica
8,301 posts, read 12,241,351 times
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Well, considering that a little slippage thereabouts caused a 9.0 earthquake and massive tsunami in Japan, I guess a plate snapping off would pretty much destroy all civilization in that half of the world.

No, the plates are too thick and heavy, plus there's the weight of the water above. There's movement, but in terms of aeons, not days.
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Old 10-31-2011, 12:10 AM
 
Location: Jefferson City 4 days a week, St. Louis 3 days a week
2,709 posts, read 4,239,395 times
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The New Madrid fault in New Madrid, Missouri is probably the most dangerous fault in the central United States. The last time there was an earthquake, it generated an 8.0 quake in 1811 or so that caused the Mississippi to flow backward, geysers to open up in the earth, houses swallowed whole, and church bells in Boston to ring.
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Old 11-01-2011, 11:21 AM
 
12,825 posts, read 20,191,056 times
Reputation: 10910
Quote:
Originally Posted by davidals View Post
Yeah - on that fault it could be hundreds of years - the midcontinental faults are far less active, and then ... bang. But the 1811-1812 series of quakes - at least 3 of them were 8.0 or greater) shifted the channel of the Mississippi River 8-10 miles in places, and were felt as far away as the New England states.

The geology of that fault is kinda fascinating. It's theorized that the New Madrid and Saint Lawrence River faults are disconnected pieces of a failed rift (like the Great Rift Valley in east Africa), where North America - well over a million years ago - began to rift apart into two separate continents. The process continued to the point of creating two faults running NE-SW from Quebec to Arkansas, and then afterwards the process of rifting stopped or died for unknown reasons. The theory is that the very infrequent (200-500 year intervals, or longer even) large quakes along that fault system are essentially the process of a dying fault system 'settling,' or slowly (over millions of years) re-setting to a true state of complete inactivity.

It's also theorized that the nearly continual swarm of too-small-to-be-felt quakes that are picked up on seismographs in SE Missouri, SW Kentucky, NW Tennessee, NE Arkansas, and far S Illinois are likely diminishing aftershocks 200 years after the main event. It will be exactly 200 years mid-December.

Something similar can be seen in the Charleston, SC area - a spike in very small quakes along a line starting in Charleston and running inland, northwest for about 40 miles - swarms of small quakes in a 50 mile radius in a state that is otherwise/elsewhere seismically dead.
It's also theorized there is a failed third arm starting at the Salton Sea then washing out into NV and from there ... ?

A few million years down the road it may prove to not be failed after all.
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