Thanks Brian and to Chris: Sorry for not being clear. What we've been observing is the pattern of quakes appearing offshore Mexico / Columbia/Costa Rica and more recently in Texas. Visually there's a pattern, at least it appears to be to us, outlining ridges of a micro plate. Since I wrote this, more quakes have appeared, most recently the Texas quakes and while not outlining this plate, they seem to look like cracking away from a point , much like lifting a brownie out of a pan (or maybe I'm just hungry for brownies!). Just wanted to know a bit more!
Thanks,
Beth

• The area I'm referring to