Chinese scientists call for better quake prediction

The seismic signal from the Sichuan earthquake Copyright: Flickr/MacEsc

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[BEIJING] Scientists in China are calling for improvements in earthquake prediction, including the establishment of an early-warning system and methods for scientists to share quake information.

The calls come after the Sichuan earthquake — the country’s most serious earthquake in 30 years — hit on 12 May (see China displays openness in earthquake response).

Ni Sidao, a professor of geophysics at the University of Science and Technology of China, says that although current scientific methods cannot accurately predict an earthquake, an early-warning system could alert people to leave for open spaces before buildings are destroyed.

Ni made his remarks last week (25 May) alongside other scientists at the China Science and Humanities Forum in Beijing, operated by the Graduate University of the Chinese Academy of Sciences.

He said that P waves — early-arriving non-destructive seismic waves — can be used to detect and calculate the scale of an earthquake within ten seconds with the aid of computers.

In the case of Sichuan, the later-arriving, destructive seismic waves (S waves) took 30 seconds to reach Beichuan — the most seriously hit county, 90 kilometres north of the epicentre — and nearly 100 seconds to reach Qingchuan County, 200 kilometres from the epicentre.

People in Beichuan could have had a ten-second warning of the earthquake with an early-warning system, allowing some to move outdoors and trains to stop to avoid derailing, said Ni.

But he admitted that current seismic monitoring stations in most parts of China are too isolated to form a warning network.

Ren Luchuan, a senior researcher at China Earthquake Networks Centre (CENC), welcomes Ni’s suggestions, but says such a system is very difficult to operate.

"[The time difference between P and S waves] is so short that it is very hard to establish a system to notify residents," he told SciDev.Net, though he says such a system could be used for key sites such as nuclear power stations, which could close reactors.

Longer-term prediction seems to be just as fraught with problems.

In the latest issue of the Chinese language journal Science and Technology Review (28 May), Wu Lixin from the Chinese University of Mining and Technology, Beijing, and colleagues report an abnormal temperature rise in the thermal satellite images of the eastern front of Qinghai–Tibet plateau — the fault that caused the earthquake — 20 days before the Sichuan earthquake.

The authors suggested this rise could be caused by tectonic plate movement, and could be an indicator for earthquake prediction.

But Ren says many factors could cause the abnormal temperature increases, leading to uncertainty in using temperature change to predict earthquakes. 

In a separate article published in the same issue, however, Wu writes that there should be more intensive, accurate and consistent analyses of thermal satellite images, and that these should be frequently checked against seismic wave monitoring.

In addition, Wu says an earthquake information sharing system should be established, so that general researchers can analyse or input data about abnormal observations into a system for professional seismologists to screen.