Necessary details

Is the Harvard magnitude the final word on size?

Does it include the ridges and fracture zones west, off the coast of the Pacific Northwest, and the Wasatch fault system to the east? I'm not clear from your description what are the eastern and western limits of your area.

A public warning would be of questionable value, most earthquakes fulfilling these criteria would have a magnitude less than 6.0, and I suspect a large fraction are on the ridges and fracture zones, 100s of miles from land and people and injure no one.

Helpful details

Any idea how likely we are to get an earthquake M5.5 or bigger in this area in a month at random, and how likely you would estimate your prediction is to be fulfilled?