BEIJING, May 27 (Xinhua) -- The aftershocks following May 12 earthquake that devastated southwest China are likely to continue for two or three months, said an expert on seismology.
"Judging from previous earthquakes of a similar magnitude, this time the aftershocks may last for two or three months, and it's not relatively long," said He Yongnian, former deputy director of China Seismological Bureau (CSB) and a seismologist, in an online interview on xinhuanet.com.
As of Monday noon, 182 aftershocks measuring above four on the Richter scale had been monitored in Sichuan, according to the China Seismological Bureau.
Five aftershocks measuring above magnitude six were monitored and the most recent at magnitude 6.4 on Sunday afternoon killed at least eight people.
"A strong earthquake, especially above 8.0-magnitude, will surely have aftershocks and they may go on for months," said He. The frequency and magnitude of the aftershocks tended to grow weaker as time passed, though they could fluctuate.
He pointed out Sichuan's mountainous terrain had increased the damage as landslides and quake lakes posed far-reaching threats to local people. If the quake had occurred in a flat area, it might have incurred much less damage.
In addition, he said, with present technology scientists were capable of ascertaining the magnitude and epicenter shortly after an earthquake, but it took longer to assess the scope of the damage as this could only be observed at the scene.
As local governments had their own emergency plans and were able to report the damage, it shortened the process a great deal, he added.
In response to questions on the odd behavior of animals before a quake, He said, "As far as we know, animals do indeed behave strangely before strong earthquakes, such as rats crossing roads and chickens roosting in trees. However, when animals behave strangely, it doesn't necessarily suggest quakes. An official organization cannot rely on that to forecast earthquakes. It's quite complicated."
The May 12 quake has killed 65,080 people and left 360,058 injured nationwide, according to the Information Office of the State Council.
汶川地震后，余震不断，对于余震的走势，中国地震局有关负责人表示，余震的持续时间还会比较长，灾区居民和救援人员最主要的还是要躲避坍塌砸伤。
主震区外不要防范过度
5月19日，地震部门就汶川大地震发布了强余震意见，中国地震局原副局长、研究员汤泉表示，严重破坏性地震发生后的震后地震趋势判定，是由有关省、自治区、直辖市人民政府负责管理地震工作的机构向本级人民政府报告并适时公告，而不是由中国地震局发布。
目前地震部门将加强地震监测预报，各级政府也应视情况启动应急预案，对可能产生次生灾害的地点，余震发生时要注意躲避，避免产生损失。主震区以外的地区，应该保持冷静，不要防范过度，住在危房的群众可采取躲避措施。
中国地震局副局长修济刚称，汶川地震区位于南北地震带中间的龙门山断裂带上，地震后已经发生20多次5级以上的余震。在灾区还应对强余震作出必要的防范，目前最主要的是躲避坍塌砸伤。
余震还会持续多长时间？
中国地震局专家罗灼礼表示，大的地震后，余震会持续一定时间，但不同地区情况并不一样。如1970年1月5日通海发生7.7级地震，2月7日发生5.7级余震；1933年8月25日茂汶7.5级地震，较大余震是11月15日的5.8级。因此，这次汶川的8.0级地震，余震还是会持续较长的时间，并会有起伏。
中国地震局有关负责人表示，总体看来，余震的活动基本是正常的，说明剩余能量在逐渐释放。在以后的释放过程当中，较强的余震还有可能发生。此前中国地震局台网中心负责人接受本报采访时也表示，预计汶川地震的余震持续将在1个月以上。
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