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I never understood this and it is hard to Google: When they say 9.0 magnitude earthquake, what does that exactly mean in terms of energy disspiated per unit time? What I consider an earthquake intuitively is some "spring" energy from faults must be released through vibration and dislocations. It is critical how this energy is dissipated and over what length of time - a strong earthquake shaking buildings for 3 hours vs. 3 seconds to dissipate the same amount of energy will cause vastly different outcomes in terms of damage.

> The Richter magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs

according to Wikipedia. Don't we need to also consider the frequency? Lower amplitude but very high frequency of vibrations can be also be dangerous? Are there any measures for Power or RMS power of an earthquake?