Earthquakes are measured on the Moment Magnitude Scale. The MMS is

a logarithmic scale, where an increase of two points indicates a 1000-fold increase in energy released. An earthquake last year in Berkeley has been estimated at 4.0 on the MMS. The Loma Prieta quake in 1989 has been estimated at 6.9 on the MMS. If a two-point increase on a logarithmic scale indicates 1000 times increase, what is the base for the MMS? How much more energy was released in the Loma Prieta quake than the one last year?