New Data Confirms Strong Earthquake Risk to Central U.S.

Live Science ^ | June 22, 2005 | Robert Roy Britt

[RegulatorCountry]

"That is the first I've ever heard of the New Madrid quake causing landsides to create the Domes in WNC"

The New Madrid quake had nothing to do with the quake in Charleston, SC in 1886 (7.6), and the Midlands quake in 1913. There is a complex system of faults that follow the Ashley River and others. The "domes" were not so much created by this Charleston quake of 1886, but were exposed by it... the shallow topsoil, trees and vegetation broke loose and slid to the bottom. This is part of the history of Whiteside Cove in Jackson and Transylvania Counties. "Old Baldie," directly behind the High Hampton Inn and Country Club, is an example of this.

http://www.eas.slu.edu/Earthquake_Center/1886EQ/sc37.html

[RegulatorCountry]

"That is the first I've ever heard of the New Madrid quake causing landsides to create the Domes in WNC"

The New Madrid quake had nothing to do with the quake in Charleston, SC in 1886 (7.6), and the Midlands quake in 1913. There is a complex system of faults that follow the Ashley River and others. The "domes" were not so much created by this Charleston quake of 1886, but were exposed by it... the shallow topsoil, trees and vegetation broke loose and slid to the bottom. This is part of the history of Whiteside Cove in Jackson and Transylvania Counties. "Old Baldie," directly behind the High Hampton Inn and Country Club, is an example of this.

http://www.eas.slu.edu/Earthquake_Center/1886EQ/sc37.html

[RegulatorCountry]

Sorry about the double post. Strange.

[Alia]

bookmark

[Black Tooth]

People in Thailand and Sri Lanka would have said the same thing if you'd asked them about Tsunamis, on Christmas Day last year.

Most west coast harbors are protected by natural and man made harbors. It would do little damage to those. And considering everything, give the overall population, very few live right on the beaches in CA. And not all but most homes are hundreds of yards from the actual shoreline. Most homes are on hills, far above the waterline. Would there be damage? no doubt, but nothing like the damage and death we saw Sri Lanka.

[Strategerist]

I was referring to the earthquake threat in SC, not comparing another tsunami threat.

Obviously there's no earthquake in SC that could even come remotely close to killing hundreds of thousands like the Asian Tsunami, but one killing thousands is within the realm of possibility.

The problem of geology is conveying threats that are widely separated in time scale; to a geologist, powerful quakes in SC are something incredibly common because there have been a lot of them in the last 10,000 years as revealed by paleoseismology.

To a person living there they're not a concern because none have happened in their lifetime or their parent's lifetime. This is a serious problem. Utah has the same issues (and they're more likely to be hit by a strong quake than South Carolina).

And in Thailand and Sri Lanka there hadn't been a tsunami that large in likely 1,500 years, and really no tsunami at all in the last 50 years. Not a person in either place had even really thought about them.

[Dog Gone]

The ground moves more near the fault, creeping a few millimeters every year, than it does farther from it.

That sounds like it reduces the chances of a quake. Earthquakes happen when rock catches along a fault and then suddenly breaks loose.

Slow movement along a fault line means nothing is catching.

[Strategerist]

Oops,

Just figured out you were using SC as "Southern California"....much of the thread was devoted to discussing SOUTH CAROLINA and to most people in the country SC means South Carolina. Sorry.

Goes double for Southern California.....there's been a flukey absence of really strong quakes in really densely populated areas in Southern California; that luck won't last.

[mountn man]

The odds of another 8.0 event within 50 years are between 7 and 10 percent, geologists said today

The odds of another 8.0 event NOT happening in the next 50 years are between 90 and 93 percent.

[Strategerist]

Given the right location a M 6-7 quake in the New Madrid Seismic Zone would still do really large amounts of damage; that's FAR more likely than another M 8.

[Flyer]

Ella Boulevard is a regular arterial street in north Houston, just west of I-45. However, the Beltway 8 overpass is far from regular. Look at the extensive steel steel structure of the overpass and the wide clear span of the steel structure.

Why was all this additional expense incurred?

Well, there is a fault running underneath the highway at this point, and the designers of the overpass decided to use a design that would not be affected by the fault. This is not a California-style fault that causes earthquakes. In fact, the Texas Gulf Coast ( and the Gulf Coast in general) is one of the most seismically inactive parts of the country. Houston faults show a gradual shift in the ground. The Long Point fault is probably Houston's best known fault. Houses built on this fault were destroyed by the ground shift. In fact, the Long Point fault runs underneath the Beltway 8/I-10 west interchange, and there were accommodations in the design to ensure that the shifting ground does not damage the interchange.

Source

The Beltway 8 main lanes over Ella include an extensive steel structure with a wide clear span over the fault.

[deaconjim]

ping

[RegulatorCountry]

"Old Baldie"

That's what they called the mountain in the children's programs, etcetera at High Hampton. It's a nickname. I believe it's formally known as Rock Mountain. I'm not claiming that all the exposed granite domes in the NC mountains are a result of the Charleston quake, jus these in the southern highlands area, Jackson and Transylvania Counties, bordering SC and GA.

[Dog Gone]

Fascinating. I'd never heard of the Long Point fault.

It's true that the Gulf Coast is seismically inactive. Anyone in the oil business knows that wasn't always so because we look for possible hydrocarbon traps caused by fault closure.

That's far more common than discovering them based on a stratigraphic feature.

Of course, we're talking millions and hundreds of millions of years ago. I'm not tempted to buy earthquake insurance here. It may not even be sold, and I'm sure I'd be looked at as nuts.

[onyx]

Cripes. I'll be accused of bringing 'em with me. :)

[Strategerist]

Only place more inactive than the Gulf Coast is the Peninsula of Florida, I think.....The Dakotas are pretty exceedingly quiet.

[snowsislander]

Yet I believe that the building codes for most of the areas likely to be hit are inadequate. Are there any active moves to try to improve the construction codes to something more like California standards or even Japanese standards? Another shock like one of the 1811/1812 series would devastate construction that did not take such shocks into effect.

I wonder what the property insurance situation with respect to earthquakes is for most businesses and individuals in that region. I have seen policies for property insurance coverage that explicitly covers such, but I wonder if some folks might not be hit with an "Act of God" clause. I also wonder how well covered the insurers and re-insurers for the region are.

[armymarinemom]

I thought the old data said the same thing.

[Dog Gone]

Certainly the highest risk is on the edges of the various plates where land masses have collided and are not moving in the same direction. But continental thrust can certainly cause earthquakes as well.

There's no way the Rocky Mountains broke and exposed themselves as peaks without a whole lot of shaking going on.

[flying Elvis]

The Charleston quake damaged water wells as far away as northwest Georgia.