[Graybeard58]

Estimated (best guess) 8.0.

That would be the low end estimate. Estimates I have seen have been 8.8 to 9.0 - A huge difference.

[Strategerist]

That would be the low end estimate. Estimates I have seen have been 8.8 to 9.0 - A huge difference.

Several recent papers have revised the magnitude estimates downward; basically no seismologists believe any of the three quakes were anywhere remotely close to Magnitude 9.

NEIC lists the largest of the New Madrid quakes at 8.1 now.

I've seen a few papers where some have it down in the high sevens; it MIGHT not have even been the largest quake in the lower 48, surpassed by either the 1857 or 1906 quakes in CA.

[Das Outsider]

The one in February of 1812 was close to MSn 9.0. Its predecessors ranged between 8 and 8.5.

[BIGLOOK]

No Richter scale then....but I believe there was another scale that measured the amount of destruction and the reaction of the population to the event. I forget what it was called. But I do recall that the upper range (above an 8.0 on the Richter scale) caused mass panic.

The 1811 quake at New Madrid changed the course of the Big Muddy. I've no doubt it also caused mass panic.

The difference between 8.0 and (low ball) 8.8 is huge; I agree.