对汶川8.0级地震前四川地区地形变类观测异常的研究  

Study on the datum anomalies of crust deformation in Sichuan region before the 2008 M8.0 Wenchuan Earthquake

作　　者：程万正[1] 苏琴[2] 孙毅[1] 

机构地区：[1]四川省地震局预报研究所,四川成都610041 [2]四川省地震局测绘工程院,四川雅安625000

出　　处：《四川地震》2011年第1期1-10,共10页Earthquake Research in Sichuan

摘　　要：研究给出四川地区跨断层短水准、短基线和固定形变台在汶川8.0级地震前出现的异常现象。四川地区跨断层流动垂直、水平形变观测场地观测,在汶川8.0级地震前出现中长期趋势异常的场地数为6个,1个为长期趋势异常,其余5个为中期趋势异常,异常观测场地比为6∕31=0.19。其中,龙门山断裂带所在的川北地区有4处跨断层流动短水准观测场地,排除影响因素后未分析得到异常项。蒲江—新津断裂带存在1项中期趋势异常。鲜水河断裂带流动短水准、短基线在汶川8.0级地震前出现中长期趋势异常的场地比是4∕18=0.22;6个半地下动态蠕变观测场地未出现异常项。安宁河—则木河断裂带流动短水准、短基线在汶川8.0级地震前出现中长期趋势异常的场地比是1∕8=0.13。对四川地区6项流动形变"疑似异常"给予说明。汶川8.0级地震前四川地区地倾斜类出现观测异常台站比是2/12=0.17;出现中长期趋势异常的观测异常测项比是5/40=0.13。另外对有争议的观测异常现象给出必要的说明。同时给出四川地区2002年1月至2008年4月四川地区周、月震情会商给出的地形变异常观测项数均值供分析比较。The crust deformation anomaly data we analyzed in the paper include the following observatories of fixed mark-stones with the methods of the fault crossing short range leveling and short baseline before the 2008 Wenchuan M8.0 Earthquake. There are 6 observatory sites with medium-term abnormal data changes and an observatory site with a long-term abnormal data changes among 31 observatory sites. In another words, the abnormal rate is 6/31. For 4 observatory sites distributed along the Longrnenshan seismic faults with abnormal data changes, the abnormal changes are carefully recognized but these abnormal changes are caused by the activity of man-made. There is an abnormal data change along the Pujiang-Xingjin seismic faults. There are 4 observatory sites with medium-term and a long-term abnormal data changes along the Xianshuihe seismic faults among 18 observatory sites and the abnormal rate is 4/18. There were no abnormal data changes of length measurement with creep-meters installed half underground. There is only 1 observatory site with medium-term and a long-term abnormal data changes along the Anninghe-Zemuhe seismic faults among 8 observatory sites and the abnormal rate is 1/8. At the same time, there are 2 observatory sites with crust tilt meters among 12 observatory sites and the abnormal rate is 2/12. The abnormal rate with the medium- and long-term is 5/40. The abnormal phenomena reported in Sichuan region before the 2008 Wenchuan b18.0 Earthquake from January 2002 to April 2008 are mentioned.

关 键 词：地形变 观测异常 疑似异常 汶川地震 

分 类 号：P315.725[天文地球—地震学]