Why the Haiti quake killed so many

Last week's earthquake in Haiti has been described by the United Nations as the worst humanitarian crisis in decades, with estimates of the number of dead ranging from 50,000 to 200,000. The UN blames the fact that the quake hit a densely populated capital city, knocking out many of the agencies that would have dealt with disaster relief.

Geologists speaking to New Scientist explained some of the other reasons why the quake was so bad, and warned that more shocks may come, because not all the pent-up seismic energy was released in the tragedy.

First, the quake was "shallow source" and so allowed less warning time to get out of buildings than deep quakes. And Port au Prince is built not on solid rock but on soil, which collapses when shaken. Finally, building standards were not adequate for major earthquakes.

If a similar quake occurred in California, the death toll would almost certainly have been much lower. "Better buildings would have saved lives," says Chuck DeMets, a tectonic geologist from the University of Wisconsin-Madison.