Newswise — Just 40 minutes before the May 12 earthquake measuring 7.9 on the Richter scale struck the Sichuan province in Central China, a Texas Tech University professor of geosciences had arrived in Beijing, only 960 miles away.
Hua-wei Zhou, professor of petroleum geophysics and seismology, was about to start work for the National Natural Science Foundation of China to monitor smaller earthquakes by the Three Gorges reservoir, 250 miles east of the Sichuan earthquake epicenter.
Now, Zhou is leading a team of six graduate students to deploy 60 seismometers to the Three Gorges area. The team hopes to record aftershocks that will help reveal the structure of the Earth's crust in this area. Though there is no reported damage to the hydroelectric dam in Three Gorges by the killer earthquake in Sichuan, Zhou said it is imperative to study the safety of the dam during an earthquake.
Failure of the dam could result in one of the worst disasters in history, as more than 75 million people live downstream of the dam, and the floodplain surrounding the Yangtze River is used for growing much of the country's food.
Zhou said the destructive earthquake occurred on the Longmenshan fault, which has many historic earthquakes greater than magnitude 7, which is capable of widespread, heavy damage. The last one occurred in 1933. "While the Sichuan earthquake is a major human tragedy, the situation could have been even worse considering that the city of Chengdu, with a population of 4 million, is just 60 miles away from the epicenter," Zhou said. "First, Chengdu is on the footwall side of the northeast-trending Longmenshan fault, and the footwall side usually has much less damage than the hanging wall side. Second, the northeast-trending fault and northeast rupture direction put most rupture energy away from the city of Chengdu and its population. "However, the region near and to the northeast side of the fault will suffer a lot, though that region has much smaller population density than Chengdu."
Another large earthquake occurred in 1973 on the nearby Xianshuihe fault to the southwest, he said.
"In 1986 I spent two months in the field studying that fault with several colleagues," he said. "The main driving force of all these earthquakes is the collision of the Indian and Eurasian plates that pushes the mountains against the Sichuan basin."
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