USGS 1811-12 New Madrid Earthquake Magnitudes Before Being Lowered To "Not Alarm The Public"

Originally posted by amongus
Did we have any sort of magnitude scale in the early 1800's? I'm confused, since I sure as hell know they didn't use decimals back then for such things...or maybe they did. How did they know ANY magnitude back then?

This is NOT a slam on the OP. I just would like to be educated.

edit on 17-3-2012 by amongus because: (no reason given)

edit on 17-3-2012 by amongus because: (no reason given)

here, educate yourself, please. the decimal has been around for a long long time, here is the bloke who created it. this should give you an idea of how long it's been around.........
en.wikipedia.org...

Originally posted by gunshooter

Originally posted by amongus
Did we have any sort of magnitude scale in the early 1800's? I'm confused, since I sure as hell know they didn't use decimals back then for such things...or maybe they did. How did they know ANY magnitude back then?

This is NOT a slam on the OP. I just would like to be educated.

edit on 17-3-2012 by amongus because: (no reason given)

edit on 17-3-2012 by amongus because: (no reason given)

here, educate yourself, please. the decimal has been around for a long long time, here is the bloke who created it. this should give you an idea of how long it's been around.........

en.wikipedia.org...

They may have had decimal back then, but they didn't have equipment to calculate magnitudes as exact as the OP suggests.

He's basically claiming these magnitudes as fact.

I don't dispute that there wasn't a number of large earthquakes then.

What i do dispute is the fact that If the USGS can't give precise accurate data on the magnitudes that happened during that time frame other than just theory, and anecdotal evidence from witness accounts, how is it possible that the OP seems to claim to know the exact magnitudes that happened then?

Where did he get these exact magnitudes from?

Did he go back in time via a time machine with a bunch of seismographs to record the data?

Anyway, I got the USGS data from before the artificial magnitude downgrade.

To the OP...Did you happen to take a screen capture of the old magnituides that USGS had up before they allegedly took them down and downgraded them so they wouldn't alarm the public?

If you did, lets see it, but i'm kind of doubting you did.

For all we know the biggest could have been a 7+, because of the bedrock in these areas being predomintaly shale, a 7+ could be catastrophic.

I'm not sure if you are aware of the Arkansas thread and the swarm of last year. People were feeling significant waves and minor damage from 3's, and 4's.

Arkansas Thread

Hi. I'm from TN and I remember studying the quakes in elementary and middle school during the 80's. The magnitudes of the quakes have been lowered since then. The numbers the op said were the original numbers were the ones we studied. I was surprised by the magnitudes of those quakes I see now in the 7 range.

Personally, I don't think a 7 is capable of making the Mississippi run backward and sinking enough land to make a body of water as large as Reelfoot Lake.

According to the United States Geological Survey, Reelfoot Lake was formed when the region subsided during the New Madrid earthquakes of 1811–1812.[1] Several eyewitnesses[2] reported that the Mississippi River flowed backward for 10–24 hours to fill the lake. The earthquakes resulted in several major changes in the landforms over a widespread area with shocks being felt as far away as Quebec.

Reelfoot Lake Wikipedia

Reelfoot Lake State Park, located in the northwest corner of Tennessee, is one of the greatest hunting and fishing preserves in the nation. The lake encompasses 25,000 acres (15,000 of which are water) and harbors almost every kind of shore and wading bird, as well as the golden and American bald eagles. Other animals are also diverse and abundant here. Its many species of flowering and non-flowering plants attract botany enthusiasts from all over the country. Cypress dominates the margins of the lake, but many other trees and shrubs are also present.

Reelfoot Lake Official Site

15000 acres of water and the river ran backward for up to 24 hours. I'm no expert, but can a 7 do that? I wouldn't think so. It basically sank the northwestern corner of TN. There's a smaller lake to the south of it as well that formed during the earthquake.

In my county, in the Cumberland Plateau, entire rivers shifted their courses and islands rose and disappeared. The river caught on fire because of the gases being released. People got sick on fumes of sulfur and methane.It was like the world was ending (that's what witnesses said). I don't know if that info is online. I read it in a historical account of our county during the earthquake. We're about seven hours or 400 -500 miles away from the epicenter of those quakes.

Oh my gosh.
Thanks for this.

I;ve never seen the separate events broken down like that,
looks like a Fukushima grade event at minimum

reply to post by tncryptogal


I'm not a huge expert either, but i would think it would depend on how shallow said quake was. If a 7+ and all it's aftershocks were shallow enough, coupled with unstable bedrock, it could well have done said damage. We just don't know officially.

Look at the how much damage the 2010 Haiti quake did and that was a 7.

Originally posted by amongus
Did we have any sort of magnitude scale in the early 1800's? I'm confused, since I sure as hell know they didn't use decimals back then for such things...or maybe they did. How did they know ANY magnitude back then?

This is NOT a slam on the OP. I just would like to be educated.

edit on 17-3-2012 by amongus because: (no reason given)

edit on 17-3-2012 by amongus because: (no reason given)

check this out ...

en.wikipedia.org...

31 nuclear power plants are in the Mississippi watershed and think about Fukushima!

www.nirs.org...

Originally posted by Red Cloak
I got a hold of the original USGS data from before they artificially lowered the magnitudes of the big 1811-12 New Madrid earthquakes. They lowered the magnitudes down by about 1.2-1.5 points, because they, "did not want the public to be alarmed by the danger posed by the fault".

You know, I was thinking about this just the other day. I remembered that the New Madrid quake(s) were always estimated at being near a 9, but then recently on the news they reported it as being a 7, which is a 100 fold difference. A hundred times smaller!! So my first thought was, where the hell did this reporter get his data for that, he's totally wrong.

So, apparently the usgs has changed the data. That's actually a little disturbing.
A 7 quake doesn't make the mississippi river flow backwards and trees replant themselves upside down while gaping holes in the earth are opened up and entire areas sublimated beneath the surface. (from witness reports at the time)

here is a History Channel video on Youtube for your educational experience.....

What would a New Madrid Earthquake look like ...check this out!

History Channel New Madrid Earthquake

reply to post by pirhanna


One thing also that could add to the Mississippi river flowing backwards is severe rain and flooding along with the earthquakes, banks bursting etc. Is there any reports of severe rain and flooding for that time period i wonder.

Just thought I would stop by and drop This Link
It does appear that the magnitudes have been tweaked a little. However, I see this as science evolving instead of them trying to hide the actual magnitude from the public.

Something as big as 8 on the NM would affect my area directly. The 4 a few weeks ago had me on edge but it seems to have settled back down for now........

That quake had to be HUGE to do all that damage..

Click here for more information.

Originally posted by Doodle19815
It does appear that the magnitudes have been tweaked a little. However, I see this as science evolving instead of them trying to hide the actual magnitude from the public.

I think there may a couple of reasons why the downgrade in magnitudes happened-

1) Propagation on the east coast vs. west coast. Because there is such solid bedrock in the east, I think they realized that an 8.5 or so would have destroyed a heck of a lot more further east than it did.

2) Intra plate quakes have been historically limited in magnitude. At least from what has been recorded in modern times so far. A 7.6 assignment for the biggest shock of Feb. 7 would seem more reasonable, and even that may be generous. When you consider I was woken up by the 5.6 all the way in WNC from the shock in VA, a 7.6 in the same context would have probably thrown me out of the bed completely.

I pretty much agree with you that this is a case of evolving science, and simple application of modern seismology principles of big quakes in different parts of the country, as opposed to some conspiracy or because "they didn't want to alarm the public". The more I deal with actual scientists, and I am now, on a daily basis, I ask them all kinds of questions- and they act surprised I would even think that they are keeping secrets in the seismology world. The only secrets I know that are being kept have to deal with temporary arrays setup to discover rare minerals and oil. Companies pay big bucks for that information, and it makes sense to keep it confidential. But guys up at the USGS for the most part tell it like it is- even though I am finding out that many of them have been involved at one time or the other with commercial exploration efforts.