Evolution of Subterranean Civilization

Modern science has provided a detailed description of our natural history. Human civilization exists in only the smallest fraction of this time and has not experienced natural disasters such as the feared super volcano, or the inevitable asteroid collision. I choose these two specifically because I believe they are the most devastating, and unfortunately the most likely to occur. Both events would cause atmospheric conditions on the surface to deteriorate so much that we would no longer be able to survive.
The best solution we have is to find another planet so that we can colonize it. This may be a hundred years out of our technological reach, perhaps much more. If an asteroid of considerable size were to strike our planet, we would have absolutely no chance. At the moment, we have no realistic plan of survival. To me, the practical answer seems obvious.

Building underground may be the future of our species. Since the beginning of civilization, man has built his structures up towards the sky. We love our sky for the warmth of the sun, and the beauty of the starry night. Yet there is no better place to survive an asteroid collision or a major volcanic eruption than the subterranean. We may have to go against our natural love of the sky, and learn to develop our civilizations downwards.

If we dedicate enough research into this area, we may develop technologies that could provide us with subterranean farms and cities. The least we could do is develop major emergency bunkers that could allow its inhabitants to survive for decades, and expand its size and functionality from within.

The keys will be a reliable power source, and an agricultural method of producing food. With a little research and development, subterranean structures could rival the mass of small cities and could support tens of thousands of people.

On a final note, there have been recent discoveries of caves on mars. These caves appear more like giant holes, showing nothing more than a black abyss inside. Mars is a planet that once had oceans, rivers, and possibly life, but its atmosphere did not sustain. Would it not have been practical for life to migrate and evolve underground? It is not the most glamorous solution, but it may be our most effective. It may even be possible that life once existed on the surface of Mars, and migrated below the surface when the conditions deteriorated. It's just a thought.