Talk:New Madrid Seismic Zone

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Merged New Madrid Fault Zone info - probably needs more cleanup. Structure needs a lot more data. To do sometime:) -Vsmith 12:00, 30 Sep 2004 (UTC)

Contents 1 cf New Madrid Earthquake 2 Propagation because of ?? 3 Mislabeled picture? 4 Largely Inactive? 5 The richter scale ratings 6 What state?? 7 Nonsensical sentence 8 Future Earthquakes. 9 High school 10 New map 11 Challenges to risk estimates

[edit] cf New Madrid Earthquake

The information in the "In New Madrid" and "In the fault zone" sections of this article disagrees on several points with the information found at New Madrid Earthquake. Can someone knowledgeable sort out which facts are correct? —Triskaideka 18:28, 12 Oct 2004 (UTC)

Reverted conflicting edit referring to Wabash River etc.. Added map from USGS. Hope this clarifies, more to do here re- the regional picture as there is evidence that the underlying structure does extend under and have imlications for southern Indiana. -Vsmith 02:10, 13 Oct 2004 (UTC)

Somewhere on the net I saw a collection of first-hand accounts of the 1811-12 quakes, including some from southern Indiana that were very striking. Kbh3rd 23:01, 23 Jun 2005 (UTC)

[edit] Propagation because of ??

Because of the unconsolidated sediments which are a major part of the underlying geology of the Mississippi embayment, large quakes here can affect as much as 20 times the land area of major quakes on the west coast.

I thought the greater extent of the effects of a quake were because of the solidity of the bedrock, not having been shattered from grinding tectonic plates as on the west coast; the shaking can carry farther through solid rock. I'll have to look for documentation of that unless someone else has it. Certainly(?) the characteristics of the Mississippi embayment soil have nothing to with an earthquake here being able to ring bells in Charleston. -- Kbh3rd 23:01, 23 Jun 2005 (UTC)

I thought so too Nat2 23:17, 1 March 2006 (UTC)

The unconsolidated sediments of the river valley and the embayment would likely result in more significant earthquake damage, but, would not result in the widespread propigation to ring the bells in Charleston. There's a lot of solid rock between the bootheel and Charleston (think Appalachian Mtns.) to propigate the seismic waves. I don't have a ref handy to quote on that. The USGS site (where the map came from) just says Differences in geology east and west of the Rocky Mountains cause this strong contrast.[1] But, there is a lot of differing geology between New Madrid & Charleston or Boston. Needs to be changed though. Vsmith 23:37, 23 Jun 2005 (UTC)

Boldly changed it :-) Let me know if I goofed. Vsmith 23:55, 23 Jun 2005 (UTC)

I wasn't paying attention to the article references to Charleston, MO – I was referring to Charleston, South Carolina. It was there or Boston or somewheres far to the east that the 1811-12 quake reportedly rang bells. Anyway, your edits stand until someone gets bolder. -- Kbh3rd 00:54, 24 Jun 2005 (UTC)

I'm not positive but, I thought this was a matter of the depth at which the fault exists and the fault in the midwest is much deeper than it is on the west coast. It makes sense, then, to assume that because of the nature of seismic waves that depth would play a major role in area of effect. The most recent quake on April 18th was at a depth of approx. 5K beneath the surface. Thestepper2001 (talk) 15:29, 21 April 2008 (UTC)

[edit] Mislabeled picture?

The picture (great, BTW) illustrating section "More quakes predicted" says Charleston, New Madrid & San Francisco but I don't see Charleston's quake marked. Jolomo 19:15, 7 December 2005 (UTC)

[edit] Largely Inactive?

There is a small quake every week... This week alone there were 8 quakes. Heck there was one today. The quakes are only measuring in the 2's though... every 6 months are so there is a 3-4 quake.

That is not inactive... in fact that is very active... the most active fault east of the Rockies.

I haven't noticed any significant quakes in that data. Still, I suppose it is the most acive fault in North America east of the Rockies. Then again, its almost the only thought east of the Rockies...Nat2 23:21, 1 March 2006 (UTC)

[edit] The richter scale ratings

Why are the sizes of the quakes on the page listed as smaller than what the USGS says? I can understand that it was a long time ago and hard to pinpoint the exact rating on the richter scale, but I would assume that the USGS would be the best authority on the subject. According to USGS Historic US Earthquakes the ratings are 8.1, 7.5, 7.8, 8.0 respectively, not 7.7, 7.0, 7.6, 7.9. I'm leaving it alone for the moment, in case someone has some better reference, but if no one has any objections, I'm going to change them to agree with the USGS information. -GamblinMonkey 15:59, 14 June 2006 (UTC)

the usgs page i looked at (the first reference on this page) said the second quake was similar or identical in intensity to the first, making it 8.1, 8.1, 7.8, 8 in any case, the page here contradicts itself by saying later that many scientists believe that the three major quakes exceeded 8, yet none of the listed ratings are over 8.

[edit] What state??

--12.153.8.43 20:19, 5 August 2006 (UTC)--12.153.8.43 20:19, 5 August 2006 (UTC)If located in northwest tennessee,what state would be located to the rite in relation to the new madrid fault? DS>South Fulton,Tn.

[edit] Nonsensical sentence

"The natural valley formed by collapsed portion of the Mississippi embayment." What? --Golbez 11:50, 29 August 2007 (UTC)

Seems that was due to a bit of vandal blanking back in March. I restored the old paragraph, should read better now. Vsmith 01:43, 30 August 2007 (UTC)

[edit] Future Earthquakes.

On Friday, April 18th, 2008, at 4:37 AM, a 5.2 magnitude earthquake occurred in this area. [7]

This is not a future earthquake. It should be moved.

As an aside: Could this recent seismic activity be a result in the uptick of activity in the yellowstone caldera? Thestepper2001 (talk) 15:31, 21 April 2008 (UTC)

No. Cheers Geologyguy (talk) 16:18, 21 April 2008 (UTC)

[edit] High school

Would it be okay to add something in this article saying that a part of the New Madrid Fault runs behind "Union County High School" in Union County, KY?209.42.180.48 (talk) 17:11, 19 April 2008 (UTC)

I don't think it would make much sense to do that. If we do that, we would have to allow every resident, whose property borders this (or another) seismic zone a mention in the article. doxTxob \ ^talk 21:26, 19 April 2008 (UTC)

[edit] New map

I added a new map that shows the approximate extents and geographic relationship of the New Madrid and Wabash Valley seismic zones, replacing a wide-area map that did not identify the zones and only had data from 1974 onwards. Maybe this map will make the distinction between the zones a little more clear and remove some confusion. Additionally, it has quakes going back farther than 1974. From my informal research (googling), it appears that Memphis U. started comprehensive monitoring in 1974, which is the beginning date for most of the maps shown. This map has older quakes (denoted in green) that go back farther. I'd like to find that USGS Professional Paper 1527 that has the older quakes in it; could be interesting. --Kbh3^rdtalk 02:52, 25 April 2008 (UTC)

[edit] Challenges to risk estimates

There's an article referenced in the Wabash Valley Seismic Zone article that has some Wash U. researches talking about how the New Madrid zone may be quieting. I also saw an article recently, I know not where, that has quotes from geologists talking about how the NMSZ may not be such a big threat after all and others saying there's no reason to be less prepared for "the big one". Is anyone qualified reading these words? Even if I had the references handy, any such discussion in the article I think should come from someone more qualified than I, IMHO. --Kbh3^rdtalk 02:24, 22 May 2008 (UTC)