To develop the new maps, researchers refigured the magnitudes and locations of nearly a thousand historic earthquakes dating back to 1000 C.E. according to strict, uniform new criteria.
Scientists know that it will happen again, we know the possible magnitude of the earthquakes to come, and we know that those magnitudes are greater than 7.
The difference in magnitudes is 2.7, so the difference in shaking is 10^2.7, or just over 500 times as big a figure you've probably seen.
The result though unlikely to settle the debate anytime soon was "a broader range of [earthquake] magnitudes and recurrence rates for New Madrid than we had before," Petersen says.
Three other relatively mild quakes have struck the region in the last century with likely magnitudes between 4 and 5, Bell notes.
Peter Malin and Eylon Shalev of Duke University examined the record of slight twitches with magnitudes of 0.1 which give off the energy of just one stick of dynamite.
Quakes that are confined to the uppermost region of the Juan de Fuca plate--the crust--have an upper magnitude of about 7, while quakes extending to the mantle level below the crust could have magnitudes as high as 8 on the Richter scale--30 timoremorenergygy than a magnitude 7 quake.
So-called moment magnitudes, used since the 1970s, are based on a more complicated formula but were designed to be comparable for most earthquakes.
For example, if the magnitude of one quake is 6 and another is 4, than the difference in magnitudes is 2, so the stronger earthquake shakes 10^2 or 100 times as hard as the milder one.
Among the movie's errors are its depiction of earthquakes with magnitudes greater than 9 (the San Andreas fault isn't long enough or deep enough to support those sizes) and the creation of the giant tsunami, which would be impossible given the fault's location.
If one invokes prior structural knowledge, usually that the crystal is composed of discrete atoms of known atomic numbers, then the observed magnitudes are, in general, sufficient to determine the positions of the atoms, that is, the crystal structure.
