I have been monitoring quakes for 12 years now. I keep USGS and Global Incident open 24/7. I had this same eye opener in 2012. I built a spread sheet with over to 40,000 quakes between 2011 and 2013 between 1km and 10km. That's 100 entry points...1.1, 1.2, 1.3...etc. Instead of random distribution, 400 or so per data point, "5.0" depth quakes were recorded 13,800 times. I tried several routs to get this to the public including George Noory and Richard Hoagland. Looks like they are cleaning out lower levels. I bet its hot as hell down there.