Probabilities, magnitude, strength How much, how soon? Six
millimeters is a quarter of an inch. Experts say if the fault is
slipping by four to seven millimeters per year, it's serious. In
200 years, it would amount to more than a yardstick's length.
When rock pushes rock that much, something will give. If it is
slipping two millimeters or less per year, experts say the next
big shake may be a bit less, delayed another 1,000 years, or
even never come. Yet, two millimeters a year x 500 years = 3
feet, rock against rock. Compare movements of other faults.
California's San Andreas fault is said to slip anywhere from 6
to 45 millimeters per year. Some mid 1990's studies attempted to
measured the movement between stations by satellite, and decided
it was very little. Permanent sites now record data
continuously. One station is attached to a 60' vertical steel
I-beam. 2009-10 update: CERI spokesman Gary Patterson says
experts are now doubting that measuring movement of the New
Madrid fault gives useful information,