The real problem using "energy" as a measure of seismicity is that one Mw 8.0
is equivalent to about 30 Mw 7.0 earthquakes, 1000 Mw 6.0 earthquakes etc.
So if a Mw 7.0 occurs, using energy considerations, you might as well forget about
all the Mw 6 earthquakes that occurred, likewise if you have a Mw 8.0, it is pretty
much the same energy expenditure as all the rest of the seismicity around the
world in the previous year (providing another Mw 8 did not occur in the previous
year). Energy, then tell nearly nothing about triggering since the Mw 8 may or
may not have been triggered, but most likely was ready to go anyway since a
lot of stress has to be built up to get an Mw 8 to occur.
In any study of triggering it is extremely important to examine what you are
looking for and then choose the appropriate data set - energy, aftershocks,
mainshocks, small shocks, microearthquakes, which is most likely from theory
to show the effect you wish to find. But energy is usually a very poor choice since
one large event wipes out the contributions of thousands of others. It's like trying
to see a previously painted picture on a canvas that has been repainted white
or trying to find a whispered note at a rock concert.