Yeah, it's called the Mississippi Embayment, of which the New Madrid fault is a remnant feature. Hundreds of millions of years ago, a chunk of North America broke off between Alabama and Arkansas. That is why the Appalacian Mountains end in Alabama and then resume in Arkansas as the Ouachita Mountains. They found the lost chunck a few years ago plastered onto South America. The embayment then became a low point for the central continent and filled in with sediments over the ensuing eons. The New Madrid fault is simply a relatively small fault in the region, as compared to a techtonic boundary such as the San Andreas, and is in the center of the North American Plate, not on the fringes.
Would a major earthquake on the New Madrid Fault be catastrophic? Heck yes. The formations in California are heavily fractured, so they do not transmit energy efficiently. The sediments in the Central U.S. are much more solid, and the damage from a 9.0 earthquake in New Madrid would be felt over a large area. However, that would not be sufficient to cause anything more than cosmetic geological changes - precisely because the fault is in the middle of the plate, and therefore is somewhat limited in impact to the greater plate motions.
As I've noted elsewhere, along about the end of Nov, beginning of Dec and after that huge meteor was in news reports as being blown apart by a UFO, Tim stated firmly that he believed that an "angelic UFO" did it.
He further more or less apologized for limiting God's response to prayer; limiting God's mercy and being so emphatic that the 9.0 would occur regardless.
He also stated well before the end of Dec that he felt the many 7.0+ quakes and the 8.3 quake in Alaska had dissipated the energy that would have been otherwise released in a huge quake had the huge meteor struck.
He has to answer to God for his errors. I am happy to give him grace. I have been disappointed in the quality of his writings and in his promises of documents that take a LOT longer than anticipated and tend to be much more anemic than anticipated. But, in the overall scheme of things TO ME, those are mostly small issues.