system
Given the following post, respond as if you're commenting on Reddit:
human
[BioShock] How does Rapture expand and repair itself?

In the BioShock series, the city of Rapture is shown to be an astounding testament to mankind's technical expertise and the tenacity of the "utopian" vision of Andrew Ryan.

In the viral game Something in the Sea, we are shown that the initial construction of Rapture (with stage I being completed in late 1946) is financed by shell companies such as Warden Yarn who buy large quantities of materiel from Scarlet Sovereign with these contracts then being reneged upon receipt of the raw materials. 

This presents a problem, however. With Ryan disappeared to Rapture and his shell companies on the surface surely made pariahs by his lack of payment on large contracts, he was surely cut off from receiving raw materials from sources on the surface. However, we're told that Rapture continued to expand until 1951. This surely would have required a vast amount of material well in excess of the sums we're shown in the Scarlet Sovereign receipts. Further, any civic planner worth a damn would have a setup for procuring additional materials for repairs and expansion to keep pace with population growth.

Now, as we're not shown any sort of method by which Rapture can quarry stone or mine ores and the trees in Arcadia are surely insufficient for providing lumber in addition to oxygenating the city, I've got to wonder: where did the additional raw materials for Raptures maintenance and expansion come from?
gpt
Ryan only needed his shells for the initial work - setting up the infrastructure to harvest the sea floor and below. He was smart, you see - placing Rapture's foundations where the crust was thin and rich in minerals. He powers Rapture geothermally, and who's to say he doesn't have a legion of Big Daddies working as miners? They do have those drills, after all.