Roger, I think I know what your columns are but am not sure: the first columb is degree of latitude: but is the box to the north or south? (is 37 from 37 to 38, or 36.5 to 37.5, or 36 to 37, or what?

the second is total number of M3 quakes in that degree band.
The 3rd is total number of M3+ quakes within 20 days of a M5.5 located south of Lat 33?

If this is correct, the distribution is very odd. Part of this, or perhaps all of it, would be incomplete catalogues for M3 quakes since 1900, and very incomplete catalogues for Mexico.

What do you think you have and what do you think it means? Less concise, please.

Chris