丽江7.0级地震前形变场动态演化与孕震信息提取研究
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摘要
本文用分段速率整体动态平差法，处理了滇西水准监测网８０年代以来的水准复测资料，并进行了形变速率多面函数拟合和垂直形变场信息分离。研究了１９９６年２月３日发生于滇西水准监测网北部的丽江７０级地震前，形变场动态演化和信息分离得到的垂直形变剪切变形、扩张变形、体积变化及准加速度等信息指标分布变化特征。结果表明：８０年代中前期，在滇西的丽江、永胜及其附近地区出现的大规模形变速率高梯度带和信息指标高值分布所反映的剧烈垂直差异运动，是丽江７０级地震前１０余年孕震应变能开始快速积累的显示；而１９８５～１９９２年形变场趋势转折与垂直差异运动显著减弱，可能意味着孕震能量积累到一定程度后，孕震区处于相对闭锁阶段。在此基础上，结合丽江７０级地震前区域地震活动分析和不同地区强震孕震形变对比，进一步研究了强震前形变场非均匀态特征和孕震信息的识别提取，得出了一些用大地形变进行强震中期预测的有益结果。
Using the integral dynamic adjustment of the piece wise liner velocity,the paper processes the levelling repetition measurement data of the Dianxi(Western Yunnan) area since 1980s,and makes the fitting of the velocity surface for vertical deformation with multisurface function and splits information of vertical deformation field.The dynamic evolution of deformation field and vertical deformation information norm shear deformation,extension deformation,volumetric deformation and quasi acceleration,the distribution changing characteristic by the information splited before Lijiang earthquake with M S 7 0(February 3,1996) in the north of the Dianxi(Western Yunnan) levelling network have been researched.The results indicate that in Dianxi(Western Yunnan) area the acute vertical differential movement of the large scale deformation velocity high gradient belt and high information norm distribution on the Lijang,Yongsheng and its adjcent areas in the medium term of 1980s is the discovery of the startting seismogeny strain energy accumulation before Lijiang earthquake with M S 7 0 for ten years;during 1985～1992,the deformation field tendency dog leg had been notable weakened vertical differential movement may be seismogenic zone that is in the relative blocking stage for seismogenic energy accumulation to definite extent.On this basis,combine the seismicity analysis of this area before Lijiang earthquake with M S 7 0 with macroseismic seismogeny deformation for different areas,the pre seismic deformation field nonhomogeneous state and the seismogeny information retrieval have been further studied,the useful conclusion of macroseismic extended forecast by geodetic deformation have been obtained.
Using the integral dynamic adjustment of the piece wise liner velocity,the paper processes the levelling repetition measurement data of the Dianxi(Western Yunnan) area since 1980s,and makes the fitting of the velocity surface for vertical deformation with multisurface function and splits information of vertical deformation field.The dynamic evolution of deformation field and vertical deformation information norm shear deformation,extension deformation,volumetric deformation and quasi acceleration,the distribution changing characteristic by the information splited before Lijiang earthquake with M S 7 0(February 3,1996) in the north of the Dianxi(Western Yunnan) levelling network have been researched.The results indicate that in Dianxi(Western Yunnan) area the acute vertical differential movement of the large scale deformation velocity high gradient belt and high information norm distribution on the Lijang,Yongsheng and its adjcent areas in the medium term of 1980s is the discovery of the startting seismogeny strain energy accumulation before Lijiang earthquake with M S 7 0 for ten years;during 1985～1992,the deformation field tendency dog leg had been notable weakened vertical differential movement may be seismogenic zone that is in the relative blocking stage for seismogenic energy accumulation to definite extent.On this basis,combine the seismicity analysis of this area before Lijiang earthquake with M S 7 0 with macroseismic seismogeny deformation for different areas,the pre seismic deformation field nonhomogeneous state and the seismogeny information retrieval have been further studied,the useful conclusion of macroseismic extended forecast by geodetic deformation have been obtained.
引文
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