Experts from the China Seismological Bureau (CSB) said on Monday the magnitude revision of the strong earthquake in southwestern Sichuan Province was due to confirmed statistics from more monitoring stations at home and reference from overseas seismological observatories.
"It is a common practice to revise the magnitude of a major earthquake," said Xiu Jigang, CSB deputy director in an interview with Xinhua.
He explained that scientists had to use statistics from a few monitoring stations to estimate the magnitude of the earthquake as soon as possible. Then as they were able to take reference of statistics from more domestic stations and with the estimated figures by the observatories around the globe, they came to a more accurate conclusion.
The first report by CSB set the magnitude at 7.6 on the Richter scale after the quake hit Sichuan Province on May 12. The quake was shortly upgraded to 7.8. Then the bureau revised the magnitude from 7.8 to 8.0 on Sunday.
The magnitude was revised upward after specialists carried out "real-time and detailed measurements of the quake according to international practices," said Luo Zhuoli, an expert with CSB.
Scientists from the United States first put the magnitude of the tremor at 7.8 and then revised it to 7.9, while their counterparts in Europe revised it from 7.5 to 7.9, and Russia, 8.0.
The quake, claiming 34,073 lives as of 4:30 p.m. Monday and leaving 245,108 injured so far, has caused serious damage to buildings, bridges and other public facilities in an area of more than 100,000 square kilometers.
(Xinhua News Agency May 19, 2008)