New Madrid Fault: New USGS Study Shows Quakes Happen at Irregular Intervals

[bjdeming]

Well, this complicates hazard planning, but overall it may be good news.

"If earthquakes happen on the Reelfoot fault every 500 years, and have been doing so for hundreds of thousands of years, we would expect to see a mountain range there—but we don't," says Gold. Instead, he suggests the modest fault scarp associated with the Reelfoot fault indicate that the earthquakes haven't been sustained over a long period of time.

. . .

"Our results will hopefully encourage the seismic hazard community to consider the possibility that the tempo of faulting may be variable," says Gold. "Sometimes there may be very long intervals between earthquakes and sometimes the earthquakes may be more closely spaced."

The USGS team hopes their new results on New Madrid ruptures can provide insights to those who model risk and seismic hazard in the region. Gold says that refining and updating seismic hazards with more information on how a fault might rupture can help with building codes—designing buildings just right to keep us safe, but not over-designed, which can waste resources.

 

[WesL]

You know I've been scared of the New Madrid since I learned about it in elementary school. Interesting article!

 

[Pam G.]

Isn't some of the Alabama Counties in that New Madrid Fault? I think my area would have maybe get some shakes if it happens.

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[bjdeming]

Isn't some of the Alabama Counties in that New Madrid Fault? I think my area would have maybe get some shakes if it happens.

Back in the 90s or whenever it was when there was all that rumor about the fault zone about to go off, my father and stepmother in McCalla were worried. I just looked up the USGS and CUSEC pages on the NMSZ and its risks. Here's an animation of a hypothetical big one there (don't look, WesL! )

And here's the most recent collection of USGS hazard maps--you can look up your area there. I'd forgotten that South Carolina occasionally throws an M7-style quake, too (for different reasons, probably). Alabama is going to feel shaking from either one of those two zones with a big enough quake. But then, so will most everybody east of the Mississippi (and a little bit west of it, too).

The good news, if this study is correct, is that such big ones don't happen as regularly as once thought. Got my fingers crossed . . .

 

[bjdeming]

Ohio-based geologist Erik Klemetti did an interesting blog post this week on Eastern quake risk.

. . .
we might be underestimating the maximum magnitude of potential earthquakes in eastern North America. This is mostly due to the fact that our current historical catalog is too short to capture the longer recurrence intervals for east coast earthquakes.
Where does that leave people living in eastern North America?

First off, remember that even though we might be undercounting and underestimating large earthquakes, they are still fairly rare events. However, that doesn’t mean it is a bad idea to be prepared . . .

 

[bjdeming]

Just came across this, from May 1st:



If you're not already following them, they note local quakes and have a lot of other interesting information.

 

[rolltide_130]

Isn't some of the Alabama Counties in that New Madrid Fault? I think my area would have maybe get some shakes if it happens.

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An earthquake along the fault on a level comparable to what happened in the 1800s would potentially cause widespread major damage across NW Alabama, mainly north of I-22 and west of I-65.

The good news is that this seems increasingly unlikely during our lifetimes from everything I've read.

The not-so-good news is that earthquake resistant structures are almost nonexistent here, even in our new construction. A major earthquake in this part of the country would be an absolutely crippling event that would change our lives as we know it and possibly kill millions.

 

[skelly]

An earthquake along the fault on a level comparable to what happened in the 1800s would potentially cause widespread major damage across NW Alabama, mainly north of I-22 and west of I-65.

The good news is that this seems increasingly unlikely during our lifetimes from everything I've read.

The not-so-good news is that earthquake resistant structures are almost nonexistent here, even in our new construction. A major earthquake in this part of the country would be an absolutely crippling event that would change our lives as we know it and possibly kill millions.

Y’all excuse me but the way this year is going I want both y’all to go out and knock on some wood. Thanks.

 

[JayF]

I remember in High School we did earthquake drills because Iben Browning predicted there would be an earthquake on Dec 3 1990. We were even out of school on that day.

 

[bjdeming]

 

[bjdeming]

Many times smaller than the big ones back in the 1800s but somewhat larger than the usual background level. This layperson sees it as just a quake, not a foreshock (which perhaps would show as multiple temblors just as strong or stronger) -- maybe there will be local news on it;