Hi BW;

I searched the NEIC database for you defined area from 1973 - present and found 13 quakes of that size.

If you run them thru the probability program you find that there are 3088 windows of 3 days 7.5 hours length in that time period and only 11 of them had all the quakes.

Your probability of success is then 11/3088 = 0.356%

Pretty slim odds, so a very valuable prediction if it pans out.

Roger