Dang, you beat me to it!
Yeah, that was a good one. I think that Stephenson grossly underestimated the number of people who would have been Diggers - there are a lot of caverns in this world, and with two years to work on them they’d support a lot of life. And, after all, they wouldn’t have had to dig for geothermal power, it would have been on the surface for them, more than they could possibly have used, which was the problem, after all, wasn’t it? But great story. I love Stephenson’s work.