Case 2: Natural Earthquakes
This method doesn't find much use, but is worth mentioning.
In which cases should it be used?
This method should only be used in case a natural earthquake occurs, as it takes into account the work necessary to overcome the friction between continent plates etc.
It should be noted that, realistically speaking, a natural earthquake
can't have a magnitude above about 9.6. So if the righter scale magnitude calculated is above that, this methodology should only be used if special circumstances apply.
How is it done?
First perform step 1 and step 2 like described in "Case 1: Meteor Impacts".
Since here one does not wish to know the energy necessary for a meteor, but for a real earthquake this time the third step has to be different.
Instead of looking at the "Energy" section, one looks at the "Seismic Effects" section again. There a value named "Richter Scale Magnitude" will be listed. This is the magnitude an earthquake would need to have to cause the described effects at the distance from the epicenter we input. The value is independent from the method through which the earthquake was caused, so it also stays true for other natural earthquakes which aren't caused by meteor impacts.
One takes the Richter Scale Magnitude and inputs it in
this calculator in the "Earthquake Magnitude" field. Then press the compute button.
The value for "Total "Seismic Moment Energy" (MO)" is the energy necessary to cause such an earthquake.
Case 3: Other
This is the most common method to calculate earthquakes.
In which cases should it be used?
This should be used if the earthquake is not caused through something very similar to a meteor impact and is also not a natural earthquake.
How is it done?
The method is identical to that of "Case 2: Natural Earthquakes", just this time instead of the "Total Seismic Moment Energy" (MO)" value our end result is the "Seismic Energy in Waves Radiated from Earthquake Source" value.
The reason one uses that value in this case is that the big energy loss that comes through the movement of the continental plate or similar processes of natural earthquakes is not present here. Instead we can only use the amount of energy that actually takes part in the effects we observer. Hence only the energy radiated in form of seismic waves is relevant for this case.