User blog comment:USS Enterprise CVN-65/The New (And Improved) Official Roleplay Room/@comment-32964013-20151229232535/@comment-11135771-20151230182759

Also, the Prometheus base isn't sitting on the crust - it's at just above sea level, several kilometres below the crust. Additionally, any tunnelling would have been detected by seismic sensors, which would obviously be in place seeing as there are at least two species of native tunnellers known to exist on Tenelapis that could pose a major threat to the base.