It was a combination of human error, indifference, corruption, and greed. And it doesn't have to be that way. A group of Las Colinas residents and environmental groups were in court only last year to stop development on that slope and the ridge above. The judge ruled against them. A former planner in San Salvador, Clarisa Rodriguez, told The Economist magazine that restrictions against building in high-risk areas are sometimes not enforced.
Experts agree that steep slopes made of volcanic soil are unstable.
Geologists know this. Planners know this. It is not an act of God that no more than 10 percent of the multi story structures in Indian cities are built according to earthquake- resistant norms. The earthquake didn't kill, but the buildings did. And the buildings go up rapidly with little planning and inspection in a boom economy like Gujarat's.