They were kids, babies, who were under the debris for 15 days without water, without food. And they took him out alive over there, alive. These are miracles that we are walking in the street of Mexico City today. As a matter of fact, I was a miracle too. I thought I was going to die. They can't survive a seismic truth--earthquakes don't kill people; buildings do. In all, 412 buildings were leveled. Thousands more were damaged beyond repair. No one knows exactly how many people perished inside. Some say 10,000. Estimates go as high as 30,000. What make the damage so great is the very ground the City is built on.

One thing is certained. The underground of Mexico City varies substantially. Doctor Shrief Christna saying is head of the seismological Institute of the University of Mexico.

In this general area, what we are right now on the University campus, there is no danger of quakes. Because this is vocanic subsoil. It is very steady subsoil. However, the lake area is a very vulnerable part of the City.

The heart of the City is built on landfill over an ancient lake bed. What was meant as a stable foundation became a seismic amplifier.Seismic waves travel from the epic center of an earthquake like ripples in the pond, loosing strength with distance, but not here. In this poorest water saturated soil, seismic waves are magnified five to twenty times. In the process called the liquid fraction, the seismic waves turn the subsoil to jerry. Buildings topple beneath their own weight.

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