At twenty-five past one in the afternoon, a magnitude 7.1 shock lifted the ground under El Asnam in northern Algeria and shook it for about thirty-five seconds. It was a Friday, 1980, the middle of the day. Buildings made of unreinforced masonry and heavy concrete floors do not bend; the walls fail, and the floors come down flat, one onto the next. Two thousand six hundred and thirty-three people were killed. More than eight thousand were injured. There had been no foreshocks, so nobody had any warning at all.

The injuries that follow this kind of collapse are mostly fractures and crush injuries, and crush injury is slow — muscle damaged under weight releases substances that can shut down the kidneys hours after the person is pulled free, which means fluids, early and in quantity, matter as much as anything surgical. A second shock, magnitude 6.2, came about three hours later, while people were still digging. The fault underneath had not been mapped before.