民乐-山丹地震的区域构造变形背景与中短期前兆
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摘要
利用青藏块体北缘地区 2 0 0 1～ 2 0 0 3年GPS水平运动资料和 1988～ 2 0 0 3年跨断层短水准流动观测资料 ,借助改进的负位错模型及断层形变应变强度比 -时变曲线 ,研究了与 2 0 0 3年 10月 2 5日民乐 -山丹MS6 1,MS5 8地震孕育有关的区域构造变形背景与中短期前兆异常。分析表明 ,在昆仑山MS8 1大震引起的大区域形变调整 -短期松弛 -开始恢复的背景下 ,民乐-山丹地震震源位于可能反映应变能积累加速的块体边界压性锁定段之间的剪应力强度增强段北侧 ;距震中最近的石灰窑口跨断层短水准流动场地在震前 3个月呈现显著应变强度比异常 ,而震前 10余天至数月内整个监测区异常个数、震前 3个月相对近源区异常集中与局部增强均是对这两次地震的某种预示
Using the data of horizontal movement during 2001～2003 observed by GPS and mobile short-leveling observation crossing faults from 1988 to 2003 in the northern margin of the Qinghai-Xizang block, aided by improved negative dislocation model and time-curve for strain intensity ratio of fault deformation, the regional tectonic background and medium- and short-term auspice abnormity related to the Minle-Shandan M_S=6.1 and M_S=5.8 earthquakes occurred on October 25,2003 are given. The analysis shows that, under the background of large-range deformation adjustment——short time relaxation——recovery caused by the Kunlun Mountain M_S=8.1 earthquake, the earthquakes located on northern side of enhanced segment of shear stress intensity which lay between two compressive locked segments reflecting acceleration of strain energy; Moreover, the Shihuiyaokou site (near epicenter) of mobile short-leveling observation crossing fault, revealed remarkable abnormity of strain intensity ratio in 3 months before those earthquakes, and the number of abnormity of entire monitoring area from 10 odd days to several months and locally enhanced and centralized abnormity region close to the epicenter in 3 months before those earthquakes foreshowed them.
Using the data of horizontal movement during 2001～2003 observed by GPS and mobile short-leveling observation crossing faults from 1988 to 2003 in the northern margin of the Qinghai-Xizang block, aided by improved negative dislocation model and time-curve for strain intensity ratio of fault deformation, the regional tectonic background and medium- and short-term auspice abnormity related to the Minle-Shandan M_S=6.1 and M_S=5.8 earthquakes occurred on October 25,2003 are given. The analysis shows that, under the background of large-range deformation adjustment——short time relaxation——recovery caused by the Kunlun Mountain M_S=8.1 earthquake, the earthquakes located on northern side of enhanced segment of shear stress intensity which lay between two compressive locked segments reflecting acceleration of strain energy; Moreover, the Shihuiyaokou site (near epicenter) of mobile short-leveling observation crossing fault, revealed remarkable abnormity of strain intensity ratio in 3 months before those earthquakes, and the number of abnormity of entire monitoring area from 10 odd days to several months and locally enhanced and centralized abnormity region close to the epicenter in 3 months before those earthquakes foreshowed them.
引文
崔笃信等,2003,青藏块体东北缘地壳水平运动动态变化与地震趋势预测,中国地震局第二监测中心2004年度地震趋势研究报告
杨立明等,2003,中国地震局“十五”项目子课题“青藏高原北部地区地震活动短期前兆特征及其预测方法研究”报告
张希等,2003,南北地震带-青藏块体北缘三维变形场及地震预测,中国地震局第二地形变监测中心2004年度地震趋势研究报告
何玉梅、姚振兴,2002,中国台湾南部及其周边岛屿现今地壳形变的位错模型,地球物理学报,45(5),638～645。
江在森、张希、陈兵等,2000,华北地区近期地壳水平运动与应力应变场特征,地球物理学报,43(5),657～665。
伍吉仓、许才军,2002,利用GPS资料反演华北块体运动的负位错模型参数,武汉大学学报(信息科学版),27(4),352～357。
张培震、邓启东、张国民等,2002,中国大陆活动地块与强震,中国科学,32(D辑增刊),5～11。
张希、江在森、王琪等,2003a,1999～2001年青藏块体东北缘地壳水平运动的非震反位错模型及变形分析,地震学报,25(4),374～381。
张希、江在森、王双绪等,2001,断层形变的应变强度比动态图像与震例综合研究,地壳形变与地震,21(2),37～42。
张希、江在森、王双绪等,2003b,川滇地区近期地壳水平运动特征与强震关系研究,大地测量与地球动力学,23(3),35～41。
张希、江在森、张晓亮等,2002,华北地区近期地壳水平运动的非震负位错反演,大地测量与地球动力学,22(3),40～45。
张希、张四新、王双绪,2004,昆仑81级地震前后地壳垂直运动的负位错模型,地震研究,27(2),153～158。
Matsu’uraM ,JacksonDDandChengA ,1986,DislocationmodelforaseismiccrustaldeformationatHollister,California,J .ofGeophysicalResearch,91(B12),12,661～12,674.
杨立明等,2003,中国地震局“十五”项目子课题“青藏高原北部地区地震活动短期前兆特征及其预测方法研究”报告
张希等,2003,南北地震带-青藏块体北缘三维变形场及地震预测,中国地震局第二地形变监测中心2004年度地震趋势研究报告
何玉梅、姚振兴,2002,中国台湾南部及其周边岛屿现今地壳形变的位错模型,地球物理学报,45(5),638～645。
江在森、张希、陈兵等,2000,华北地区近期地壳水平运动与应力应变场特征,地球物理学报,43(5),657～665。
伍吉仓、许才军,2002,利用GPS资料反演华北块体运动的负位错模型参数,武汉大学学报(信息科学版),27(4),352～357。
张培震、邓启东、张国民等,2002,中国大陆活动地块与强震,中国科学,32(D辑增刊),5～11。
张希、江在森、王琪等,2003a,1999～2001年青藏块体东北缘地壳水平运动的非震反位错模型及变形分析,地震学报,25(4),374～381。
张希、江在森、王双绪等,2001,断层形变的应变强度比动态图像与震例综合研究,地壳形变与地震,21(2),37～42。
张希、江在森、王双绪等,2003b,川滇地区近期地壳水平运动特征与强震关系研究,大地测量与地球动力学,23(3),35～41。
张希、江在森、张晓亮等,2002,华北地区近期地壳水平运动的非震负位错反演,大地测量与地球动力学,22(3),40～45。
张希、张四新、王双绪,2004,昆仑81级地震前后地壳垂直运动的负位错模型,地震研究,27(2),153～158。
Matsu’uraM ,JacksonDDandChengA ,1986,DislocationmodelforaseismiccrustaldeformationatHollister,California,J .ofGeophysicalResearch,91(B12),12,661～12,674.
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