When all the animals that live in holes start coming out of their safe areas in order to be outside ... THEN ... I would start to worry.

Fwiw I would think the sulfer smell would be around for a few days or weeks before anything would happen.

Because the New Madrid is a DEEP (not surface) fault complex it is much harder to model or understand than a fault complex that comes close to or even reaches the surface.

Last time around, though this local was not in the direct line of fire, the shaking was alledgly so bad that most chimneys toppled over. St. Louis and Memphis ARE however in the direct line of fire and they could have a LOT of their older unreinforced masonary buildings collapse (and both of those towns have LOTS of those type of 1800's buildings) if a repeat of ANY of the quakes of 1811 & 1812
were to reoccure