I was just wondering if anyone knows if any work has been done in tabulating the total seismic energy expended for a region on a daily basis, so that trends could be identified or patterns established.

For example, use the following formula for every earthquake occurring in a given region in a 24 hour period:

log E = 1.44M + 5.24
or, rearranged, E = 1.74 X 10^(5 + 1.44M)

Where E = Energy (in Joules)
and M = Magnitude of the individual quake

Next, you would simply add up all of the energy from the individual quakes to determine the total energy output for the day.

Thanks, Billion
http://www.billionwatts.com