China quake forces rethink over hazard maps
Following the Sichuan earthquake, in which more than 65,000 people died, researchers say that similar regions may also be in danger and that seismic hazard maps should be redrawn
When more than 65,000 people died in May in a region of China thought to be at a low risk of quakes, geologists realized their hazard maps must have serious shortcomings. Now a coalition of geologists from the Massachusetts Institute of Technology and the Chengdu Institute of Geology and Mineral Resources, Sichuan, say that similar regions may also be in danger and that seismic hazard maps should be redrawn. Using historical, geological and GPS records, the scientists modelled movements in the Earth’s crust that led to the quake. This shows that although the crust in the region is being compressed very slowly, at around one millimetre per year, strain had been building for over 1,500 years.
New Scientist reports that for Sichuan province, they calculate that the next big earthquake is not due for at least 2,000 years, but for other regions with similar mountainous slopes, a large earthquake could be just around the corner. The team has highlighted the edge of the Tibetan plateau as one such region. Clark Burchfiel at MIT, who is the lead author of the paper, says: “We need to re-evaluate the criteria we use for assessing earthquake hazard.”
-read more in B. C. Birchfiel et al., “A Geological and Geophysical Context for the Wenchuan Earthquake of 12 May 2008, Sichuan, People’s Republic of China,” Geological Society of America Today 18, no 7 (July2008)