Hi Brian and Beth. This morning the guage at New Madrid is at 47.19 feet with the forecast being 50 feet in a couple of days. The old record was 48 feet. Majpr flooding stage is 44 feet. Flood stage is 34 feet. The record low stahe is -3.6 feet. So, the forecast stage is 53.5 feet above the lowest stage, which was in 2006. Much of the Mississippi is leveeded in, so it is like a reservoir, although a very long one.

It does not have to take very long to trigger earthquakes: short-term fluctuations at a reservoir in South Carolina of about a meter were obviously associated with seismicity (but very shallow seismicity I think).

And, there is not a M5 limit: Lake Kariba in Zambia (?) which may be 200 m-deep is associated with a 6 1/2, and Nano Seeber, I think, told me there was a M7 in India. Theer was a deep quake at, I think Oroville California that may have been associated with a reservoir. The last may have taken a few years.

Water does not have to "percolate down". The increased vertical stress is instant by placing the load (but may not trigger anything). If you have any kind of connection to deep through faults, the pore pressure can increase just by having a larger "head". True, in shales with no fractures this would not happen. But, I saw a talk once where injecting fluid in one well in an oil field for enhanced production could cause pressure changes at depth at surprisngly long distances (few km????). This would be be in sedimentary rocks.

So, is not the first flood on Mississippi and someone (Roger? Brian?) could look at river level vs. M2+ quakes (after finding a complete catalogue for M2+ quakes. If nothing happened for previous major floods, then nothing is likely this time except by chance.

Chris