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.

I will try to explain it. What I am saying is that these were the ESTIMATED magnitudes for the quakes before they downgraded them recently. Keep in mind that the USGS is conservative and almost always assigns lower magnitudes for quakes than the other agencies around the world.

Like 2004's Indonesian quake is seen as a 9.3 in most places, but as a 9.1 by USGS. The Japanese quake as a 9.1 in most places, but as a 9.0 by USGS, and they tried to mark it at 8.9, but too many other scientists would not go along with it, so they went with 9.0, versus the 9.1 of others.

So, they are always conservative with their magnitude estimates. The point is, that these were the estimates up until a few years ago, when they suddenly drastically lowered them without any plausible explanation.

I have looked over all of the research thesis papers they used to justify lowering the magnitudes, and the work done is amateurish at best, and really is complete nonsense. It would not hold up under any outside scrutiny at all.

So I was looking for the original numbers before the downgrade, to give us a better grasp of what the situation with that fault is. Since, every USGS source now is claiming the quakes were 7s range at most. It's important to understand that this is something USGS just did with very shady "science" off some thesis reports.

Yes, you are correct in that these quakes were not measured. So these are estimates. But that is the point. Meaning, that the estimates that are being touted now are completely wrong.

I am not even saying that the magnitudes I posted here are correct. Those are estimates also. But it is much closer to the reality than what they are claiming now.

As far as what were the actual magnitudes of the quakes - well, I have done the energy calculations myself, going with the data I have been able to personally gather. I did the estimate for the 2 main quakes on December 16, 1811, and for the last large quake of the day of February 7, 1812.

The magnitudes I got, doing my own calculation, was around 9.2 for the two main December 16, 1811 quakes, and around 9.6 for the largest of the quakes that hit on February 7, 1812.

So, from my own personal calculation, even these original USGS numbers are way too low. But, the point of the thread was just to show that up until just very recently, the scientists were generally in agreement, under the conservative numbers the USGS allows, putting the quakes at 8.4 - 8.9 range.

Now, we have USGS putting numbers around 6.6 - 7.0 range.

From doing my own calculations on it, I personally found no possibility whatsoever, for any of the 4 largest quakes being under magnitude 9.

Let me just say this..........if I do the numbers on Japan, I get 9.1 - 9.3, where USGS says 9.0. If I do the numbers on Chile's 1960 quake, I get 9.6, where USGS says 9.5. Understandable, as I said, USGS is conservative and the other agencies around the world usually have higher numbers.

But when I do New Madrid's two big December 1811 quakes, I get about 9.2 (old USGS said maybe 8.6), and on the big 1812 quake, I get about 9.6 (old USGS said maybe 8.9).

So, this is more within the realm, considering that USGS is conservative and that the quakes were not actually measured - and more to the issue, the number of quakes involved, the time lapse, and the small number of witnesses near the epicenters.

Here is the problem. I cannot do the math and get say, a 9.6 magnitude for the February 7, 1812 quake, and then believe these claims by USGS that it was no more than maybe 6.9 - 7.0 in reality.

I can look in the region and see the rock strata data that shows hundreds of quakes of that magnitude in that time. Hundreds, not just one. If USGS really thinks a New Madrid quake can rock church bells in Boston for 5-6 minutes, and only be a 7, then they are completely incompetent.

The point is that they have simply changed the magnitudes to something that they think people will not consider a threat, and thus would not move out of the area, even if they thought an earthquake was imminent.

Point of emphasis, there are sand blows as far as 70 miles away, that I have personally seen from the December 16, 1811 quakes. The amount of material released was tremendous, with large rocks being thrown. This is 70 miles from the epicenter area, in a hard ground area. Now, we have some scientists claiming that this same quake was no more than a 6.8 based on their research, and the USGS backing this up.

A 6.8 quake could not make a large sand blow with large rocks ejected high into the air, 70 miles from near the epicenter, in a hard ground area.

The 6.3 here in Christchurch last year cause huge amounts of damage and severe flooding and liquefaction to large parts of the city.

A shallow quake, especially near any kind of river bed areas, swamp, marsh etc is likely to have big effects.

Even aftershocks of between 5-6 have caused large amounts of liquefaction here. It does not need to be a huge quake in order for some substantial things to happen.

And my thoughts on the OP are that back then there's no way they would have had the technology to measure any quakes very accurately. And it's ridiculous to suggest they would lower the figures to keep the public calm. Quakes will happen and their affects will be felt regardless of what it says on USGS. Most people have probably never heard of and ever look at actual data anyway. It's only after these things happen that people realise that these sites exist.

Even today, some countries quakes are monitored poorly. Even here in New Zealand, within the last month we have updated software to allow for faster and more accurate deatailing of our quakes. Now quakes are on the site within 2 minutes of them happening, compared to around 20 minutes up until February 2012. Also we can now see quakes of much smaller magnitude that most people would not feel. Several aftershocks have happened at very specific locations, including very near our house, and the next day, no one elsemhave heard or felt it apart from you. Now we can see these registered.

beta.geonet.org.nz...

'feds are preparing for the most disastrous quake in us history'

reply to post by BiggerPicture


Good vid..with the exception of it saying that conspiracy theorists are crazy...

reply to post by Red Cloak


Some questions...

As far as what were the actual magnitudes of the quakes - well, I have done the energy calculations myself, going with the data I have been able to personally gather. I did the estimate for the 2 main quakes on December 16, 1811, and for the last large quake of the day of February 7, 1812.

Where have you gathered this data and energy calculations? And why are you not showing us these calculations you did, where you got the energy release data from and any other data you are talking about?

I would expect it's very hard to figure out the energy release from quakes that happened 200 years ago when there were no instruments to record it. So how exactly did you come to and conclude these estimated calculations?

I can look in the region and see the rock strata data that shows hundreds of quakes of that magnitude in that time.

Can you show us this Data?

Also, if i remember rightly. Wasn't there a 5.6 in Oklahoma mid last year that was felt in the surrounding states?

Here's the thread:
5.6 just hit Oklahoma

reply to post by Red Cloak


I knew they were off on their numbers for the simp,e fact it made the great Mississippi run backwards and perminatly changed the course of other rivers. A 7.0 does not do that to the best of my knowledge.

reply to post by Red Cloak


I've actually read a few articles that had it originally at 9.1-9.2, which is absolutely insane. I mean, these earthquakes made the Mississippi River run backwards. It made church bells chime in Boston. They created lakes, sand blows, and the damage has changed the landscape so much. I really do think they've changed the magnitudes a LOT, I think they were a lot more damaging than they let on.

People that live around there can see the damage it caused still...

It's said to be a lot more powerful than any fault in the USA...I really do think it will unleash power again, and a lot sooner than they're telling us.

Oh, and I live 10 minutes from the Oklahoma border and didn't feel the 5.6 earthquake. I *barely* felt the Arkansas 4.2 earthquake last year, so I really don't think the New Madrid earthquakes were merely 6's & 7's. I live IN Arkansas.

This is how they got their info -

Constraints on the faulting that took place during the 1811-1812 earthquakes comes primarily from three sources: (a) historical accounts, including far-field intensity data and eyewitness reports from the epicentral zone (Figures 1 and 2), (b) seismological effects remaining from the earthquakes, such as preserved liquefaction features and present-day seismicity in the rupture zone (Figure 3), and (c) the physical structure of the crust of the 1811-1812 fault zone (Figure 4). Two additional and potentially powerful constraints are: (d) forward modeling of coseismic static strain fields to match with known topographic changes in the meisoseismal area and (e) geodetic/GPS measurement of the postseismic viscoelastic crustal relaxation still occurring today from the 1811-1812 faulting. Exploratory studies in both areas have been done (Gomberg 1992, Gomberg & Ellis 1994, Rydelek & Pollitz 1994), but the topographic and strain-rate databases must be considerably improved before they contribute significant constraints that rank with (a)- (c).

This is what they say about trying to estimate the magnitude -

A historical perspective is important for assessing both the near- and farfield effects of the New Madrid earthquakes. Figure 1 shows that the epicentral NEW MADRID EARTHQUAKES region was on the forward edge of European settlement. Kentucky and Tennessee became states in 1792 and 1796, respectively; they were the only two states of the Union with territory in the meisoseismal zone, which lay primarily in what would become the states of Missouri (in 1821) and Arkansas (in 1836). The restricted population distribution (contoured in Figure 1) is a major problem in estimating the earthquakes' sizes from far-field isoseismal data (see Section 5).

One of the first magnitude estimates -

On the basis of the extensive macroseismic effects including massive liquefaction, fissuring, subsidence, or uplift of landforms; violent disturbance of the river; and destruction of extensive tracts of forests (Table 2), both Davison (1936) and Richter (1958) considered the principal New Madrid events to be "great" earthquakes. In Richter's case, this presumably means a Richter magnitude MR ³ 8, although he never explicitly assigned a magnitude value. In Davison's case, this put New Madrid in the company of the famous 1755 Lisbon, 1897 Assam, 1906 San Francisco, and 1891 Nobi earthquakes, among others. Both authors' estimates were based on the work of Fuller (1912) and consisted more of informed judgment than of quantitative analysis.

Source

The source is a good read if you have a few minutes to kill. They look at three or four different perspectives and try to pick what they think is the best representative out of them.

I really don't believe that they are "hiding" anything from us. I personally think they are just trying to figure it out themselves with the very small amount of info that they have. I think this sums it up -

Globally it dominates all other documented earthquakes of stable continental regions (SCR) (Johnston et al 1994), a category of plate interiors that incorporates roughly 25% of all crust and fully two thirds of all continental crust. Why the New Madrid earthquakes are unique remains an enigma. Perhaps, given sufficient time, other stable continental plate interiors will experience earthquakes of the magnitude and numbers of the New Madrid sequence, although the worldwide historical record does not reveal a comparable sequence.

They have nothing else to compare it to.


E.T.A. TrueAmerican, if you are still around can you teach me the difference in MAGNITUDE and what they are talking about with the other M things in the source? They lost me a little there

Ello all,just to back up the o.p.
I was listening to john moore and lucas chatting on a show a couple o years back and heard john mention the downgrading of the richter scale,i posted the same post as the op here on another website and was asked to back it up.i personally messaged john moore to ask if i was correct in thinking this is what he had said.
He confirmed that was the case

thelibertyman.com if u wanna check out john.