When did the earthquake happen in Tangshan?

A great earthquake happened on July 28, 1976 in Tangshan, China. 250,000 persons died in it. It also cut off electricity and water supply, many houses caught fire and a great many people lost their homes. We can not stop it but we can do something to avoid suffering a great loss again. We can’t build houses along the lines where earth’s two of the plates join together. We must build them on rock not on sand. And the buildings have to be made as strong as possible.