Off the coast of Chile a strong shallow earthquake triggered a tsunami. Warnings have been going out to Chile, Peru, Hawaii and New Zealand.
The first estimation of the energy of the earthquake was at M7.9 but was then corrected to 8.3. This correction results in an update of the tsunami predictions. I created this animation from the NOAA data.
So a change of .4 in Magnitude resulted in this significant change of tsunami propagation forecast.