对汶川8.0级地震前四川地区地形变类观测异常的研究
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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 Longmenshan 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 M8.0 Earthquake from January 2002 to April 2008 are mentioned.
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 Longmenshan 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 M8.0 Earthquake from January 2002 to April 2008 are mentioned.
引文
[1]郝晓光,胡小刚.宽带地震仪资料证实汶川大地震“震前重力扰动”[J].地球物理学进展.2008,23(4):1332-1335.
[2]郝晓光,胡小刚,许厚泽,钟敏,方剑,郝兴华,刘明,刘根友,薛怀平.汶川大地震前的重力扰动[J].大地测量与地球动力学.2008,28(3):129-131.
[3]顾国华,王武星,徐岳仁,李文军.区域网GPS观测得到的2008年汶川Ms8.0级地震前的地壳水平运动[J].地震学报.2009,31(6):597-605.
[4]傅容珊,万柯松,崇加军等.地震前兆还是其他因素?——与“汶川大地震宽带地震仪短临异常及成因初探”作者商榷[J].地球物理学报,2009,52(2):584-589.
[2]郝晓光,胡小刚,许厚泽,钟敏,方剑,郝兴华,刘明,刘根友,薛怀平.汶川大地震前的重力扰动[J].大地测量与地球动力学.2008,28(3):129-131.
[3]顾国华,王武星,徐岳仁,李文军.区域网GPS观测得到的2008年汶川Ms8.0级地震前的地壳水平运动[J].地震学报.2009,31(6):597-605.
[4]傅容珊,万柯松,崇加军等.地震前兆还是其他因素?——与“汶川大地震宽带地震仪短临异常及成因初探”作者商榷[J].地球物理学报,2009,52(2):584-589.
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