Zhao further envisions going even deeper, to enable underground spaces with multiple levels.

CNN: Why Singapore is putting its oil back into the ground

"Planning is important...because underground spaces you can't remove afterwards, " says Zhao.

CNN: Why Singapore is putting its oil back into the ground

Though it has been seven days since anyone was pulled alive from the rubble, Angeli, Steelman and the other underground rescue workers are saying there are enough open spaces, with food and water, for people to survive.

CNN: workers

Changes in perception may be needed as JTC are now looking into heading downwards for spaces housing people -- rather than oil -- in the form of an underground science city.

CNN: Why Singapore is putting its oil back into the ground