The "Earth" in Earthquakes, Revisited

So apparently, when NASA told us how the Chilean earthquake altered the rotation of the earth, they didn't actually measure this, it was computer modeling. Now, someone has actually tried to measure it, and found ... nothing. Apparently, the Sumatra earthquake in 2004 packed a little more punch.

This evaluation differs from those obtained using theoretical models of the planet (such as the one produced by the Jet Propulsion Lab in Pasadena, California) which can estimate the extent of a shift on the basis of geophysical and seismological data. This is the type of calculation used in meteorological forecasts, which are based on data observed before a particular date and on theoretical models of how atmospheric phenomena develop.