Ken Silber says that space settlers may be living in caves.

Each time I hear these proposals I think of the many craters on the surface of the moon. I wonder just how stable is the crust of the moon. At least the portion we are thinking about using in this excavation. I don’t suppose there have been any geological surveys?

There's plenty of evidence of collapsed lava tubes on the moon. One may think there are useful uncollapsed (and stable) ones as well. Would Ground Penetrating Radar be useful in locating them?

Ultimately, this could look like the Antarctic bases that utilize geodesic domes. The domes are unheated, they just protect the individual structures within them from the elements. Likewise, the kind of habitable modules we know and envision (like inflatables) today could do well in Lunar caves, protected from meteorites, solar/cosmic radiation and temperature extremes.

Yes I was thinking also that an inflatible structure placed at the entrance to a cave would be good at conforming to a rough or asymetrical opening to make a tight seal. Hatches placed on either end of the inflated structure would lead into a integrated airlock. There would need to be some kind of purge system as well to blow out waste gases and contaminants. I'd imagine once you've pressurized the cave behind the plug that it would become a rather dusty and sooty environment.

I'd imagine once you've pressurized the cave behind the plug that it would become a rather dusty and sooty environment.

Insofar as moon dust is probably toxic to some degree, spraying the lava tube interior with some form of plastic, before pressurizing, might be prudent. I can foresee folks selling rolls of TransHab fabric (like Tyvek housewrap is used today) at the LunaDepot home supply store which is affized to lava tube walls like wallpaper.

LunaDepot...you'd better trademark that one, so perhaps your children or grandchildren can open up the actual store. :-)