Haiti's official seismologist, who predicted the recent earthquake, has warned that an even stronger one is likely to hit Port-au-Prince within the next 20 years. Now the Haitian government is debating how and if the capital should be rebuilt - or if it should be moved elsewhere.

Claude Prepetit had seen it coming in his figures. He had done the calculations, in millimeters and in centuries, he had calculated the pressure that was building up beneath his feet, and he had estimated the energy that would eventually be discharged. And when the earth finally did shake, and falling concrete ceilings, stone walls and wooden beams killed at least 170,000 people within the space of 40 seconds, that was when Prepetit thought to himself: "This is it - this has to be a seven."

He had predicted an earthquake with a magnitude of about 7.2 points on the Richter scale, and the actual quake measured 7.0. For years, he had taken precise measurements and performed careful calculations, and he had done his job exceedingly well.

When the earthquake struck, he was sitting at home in front of his computer. He jumped up and took shelter in the doorframe, because good doorframes are more capable of standing up to an earthquake than walls, something that Prepetit knows well. In fact, as the Haitian government's official seismologist, he knows everything about earthquakes.

In those 40 seconds, his brother-in-law and some of his friends died. Shortly afterwards, his father-in-law also died. Prepetit survived. After having spent years warning about the possibility of an earthquake striking Haiti, he can hardly be blamed for what happened there.