China is no stranger to massive earthquakes. In 1976, a quake measuring 7.8 on the Richter scale killed at least 250,000 people—some estimates put it as high as 600,000—in the north of the country. That quake was one of the most deadly in recorded history, prompting Beijing to introduce tougher building codes in vulnerable areas. The catastrophe that hit the southwestern province of Sichuan on Monday, showed that these measures weren't tough enough. Shaking buildings from Beijing to Bangkok, the quake quickly buried thousands of people under rubble, including some 900 children trapped underneath a school in Dujiangyan City.
Less than 24 hours after the quake hit, the death toll had climbed close to 10,000 and state media reported the razing of 80 percent of the buildings in a single county. That casualty count is expected to rise still further as rescuers get closer to the epicenter of destruction. Could some of these deaths have been prevented in this notoriously high-risk area? And what chances do those trapped under the rubble have of surviving the wait to be dug out? NEWSWEEK's Katie Paul spoke to Weimin Dong of Risk Management Solutions, who has served on technical committees at the California-based Earthquake Engineering Research Institute and has studied earthquake-related insurance issues in China. Excerpts:
NEWSWEEK: This region suffered several smaller earthquakes earlier this year. Was it prepared for something like this? Weimin Dong: This is a moderate earthquake area, which in the Chinese design code is specified using an intensity number of 7 for new buildings. Beijing, for example, is 8, and other areas could even be a 9, which is much [more severe]. At the epicenter area of this earthquake, the intensity was actually about 10. But the design required for this area is only for an intensity of 7, which I think explains a lot of the damage for the buildings in the area. That's different from magnitude, since each earthquake has only one magnitude, while intensity looks at ground motion in areas far from the epicenter, which receive less intensity. Here, the highest intensity for this earthquake is about 9 to 10, and it goes down to 5.
Could you give a sense of how much worse a 9 or 10 is than a 7? It determines how much force a building will be able to resist. So if a building is designed for an intensity of 7, then for an intensity of 9 it will probably collapse or suffer severe damage.
And in this region, most buildings are only built for an intensity of 7? That's the best. China's earthquake design code was not enforced until 1978, following the Tangshan earthquake. Before 1954, there was no design code. From 1964 to 1978, there was a very rudimentary design code. After 1978, that was a wakeup call. But in the rural areas, a lot of the buildings are old and were built before that, and the requirement for the intensity 7 is only for new building. Many of the buildings in the area were not designed for earthquakes at all.
How rural is the area? Could you describe the kinds of building that one would find there? The city Chengdu, the capital of Sichuan province, is about 95 kilometers [almost 60 miles] from the epicenter. This area has a lot of masonry building, brick building, adobe building. Some maybe have a wood frame building with some clay surrounding it. The buildings aren't really engineered. They do have some reinforced concrete buildings that I saw in several pictures, but those were still built for an intensity of 7 and would not be strong enough to resist an intensity of 9 or 10. [Based on that] we shouldn't be surprised that 80 percent of the buildings collapsed. -- this post is updated in 2008-5-15 20:20:16. |