青藏高原北部地区构造变形特征及与强震关系
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摘要
通过对1993～1999、1999～2001年青藏高原北部地区GPS水平运动资料的非震负位错模型反演和形变应变场时空演化分析,结合地质构造和有资料积累以来的强震活动,研究块体及边界带的构造变形特征,以及与强震孕育的关系.结果表明:(1)5级以上,特别是6级左右及6级以上地震多发生在区域应变场剪切应变率或面膨胀率高值区、边缘或其附近,尤其是与区域主干断裂构造运动一致的剪切应变率高值区;形变差异显著的块体边界附近;沿块体边界断裂带的高应变积累的闭锁区段及其附近.(2)1999～2001年较1993～1999年大范围的水平运动速率明显减弱,但应变率的减弱幅度不大,可能揭示昆仑山口西8.1大震孕育对北东向的构造应力传递起了某种"阻隔和调制作用"及太平洋板块的西进作用加强.(3)目前应变场分布高值区、块体间差异运动显著的边界带及高应变积累闭锁段有阿尼玛卿断裂中东段与鄂拉山断裂交汇区、祁连山构造带中东段及与海原断裂西段交汇区、日月山—拉脊山断裂与西秦岭北缘断裂交汇区、庄浪河断裂与西秦岭北缘断裂交汇区、六盘山断裂附近.
Through inversion of aseismic negative dislocation model and analysis of time\|space evolution of deformation and strain fields for horizontal velocity data during 1993～1999 and 1999～2001 measured by GPS,combining with geological tectonics and strong earthquakes activities,the tectonic deformation characteristics of blocks and their boundaries and their relationship to development of strong earthquakes are studied.The results show that:(1)Most of the earthquakes of Ms≥5.0,especially about and over 6 magnitude, took place in or near the high vaule region and its margins of shear strain rate or superficial expansion rate of regional strain field,especially high value region of shear strain rate in accordance with main fault;block boundary and its nearby with obvious deformation difference;locked segment and its nearby of strong strain accumulation along fault zone of block boundary.(2)During 1999～2001,combined with 1993～1999,large\|range horizontal velocity decreased remarkably,but the extent of decreasing of strain rate were small, maybe revealing that the development of Kunlun mountain pass Ms8.1 acted something of 'obstructing and adjusting' on transferring of northeastward tectonic stress, and the westward action of Pacific Plate strengthened.(3)Up to now,high value of strain field, boundary zone with obvious motion difference between blocks and locked fault with strong strain accumulation lies in the meeting region of the middle\|east segment of Animaqing fault and Ela Shan fault, that of the middle\|east segment of Qilian Shan tectonic zone and west segment of Haiyuan fault, that of Riyue Shan\|Laji Shan fault and north margin fault of western Qinling mountains, that of Zhuanglanghe fault and north margin fault of western Qinling mountains, nearby of Liupan Shan fault.
Through inversion of aseismic negative dislocation model and analysis of time\|space evolution of deformation and strain fields for horizontal velocity data during 1993～1999 and 1999～2001 measured by GPS,combining with geological tectonics and strong earthquakes activities,the tectonic deformation characteristics of blocks and their boundaries and their relationship to development of strong earthquakes are studied.The results show that:(1)Most of the earthquakes of Ms≥5.0,especially about and over 6 magnitude, took place in or near the high vaule region and its margins of shear strain rate or superficial expansion rate of regional strain field,especially high value region of shear strain rate in accordance with main fault;block boundary and its nearby with obvious deformation difference;locked segment and its nearby of strong strain accumulation along fault zone of block boundary.(2)During 1999～2001,combined with 1993～1999,large\|range horizontal velocity decreased remarkably,but the extent of decreasing of strain rate were small, maybe revealing that the development of Kunlun mountain pass Ms8.1 acted something of 'obstructing and adjusting' on transferring of northeastward tectonic stress, and the westward action of Pacific Plate strengthened.(3)Up to now,high value of strain field, boundary zone with obvious motion difference between blocks and locked fault with strong strain accumulation lies in the meeting region of the middle\|east segment of Animaqing fault and Ela Shan fault, that of the middle\|east segment of Qilian Shan tectonic zone and west segment of Haiyuan fault, that of Riyue Shan\|Laji Shan fault and north margin fault of western Qinling mountains, that of Zhuanglanghe fault and north margin fault of western Qinling mountains, nearby of Liupan Shan fault.
引文
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[13] 张希,江在森,张四新.借助最小二乘配置整体解算地壳视应变场[J].地壳形变与地震,1998,18(2),57～62.ZhangXi,JiangZaisen,ZhangSixin.Wholecalculationofthecristalapparentstrainfieldwiththeaidoftheleastsquarecollocation[J].CrustaldeformationandEarthquake,1998,18(2):57～62(inChinese).
[14] 张希,江在森.用最小二乘配置获得地形变应变场动态图像的几个问题研究.地壳形变与地震,1999,19(3):32～39.ZhangXi,JiangZaisen.Studyonsomequestionsofdynamicpicturesofcrustaldeformationandstrainfieldsobtainedbytheleastsquarecollocation[J].CrustaldeformationandEarthquake,1999,19(3):32～39(inChinese).
[15] 江在森,张希,陈文胜,等.地形变资料求解应变值尺度相对性问题研究[J].地震学报,2000,22(4):352～359JiangZaisen,ZhangXi,ChenWensheng,etal.Studyonscaledependenceofstrainvalueobtainedfromcrustaldeformationdata[J].ActaSeismologicaSinica,2000,22(4):352～359.
[16] 江在森,张希,王双绪,等.昆仑山口西Ms8.1地震前区域构造变形背景[J].中国科学(d辑)(2003年待刊)JiangZaisen,ZhangXi,WangShuangxu,etal.RegionaltectonicdeformationbackgroundbeforeMs8.1earthquakeonthewestofKunlunmountainpass[J].ScienceinChina(SeriesD)(willbepublishedin2003)
[17] 徐菊生,赖锡安,卓力格图,等.中国大陆西部地区现今的块体运动[J].地壳形变与地震,2000,20(2):15～23XuJusheng,LaiXi'an,Zhuo Li
[2] YuShui beih,JacksonDD,YuGuey kuen,etal.DislocationmodelforcrustaldeformationintheLongitudinalValleyarea,easternTaiwan[J].Tectonophysics,1990,183:97～109.
[3] 伍吉仓,陈永奇.一种板块边界断层运动的力学模型[J].地壳形变与地震,2000,20(2):8～14.WuJicang,Chenyongqi.Amechanicalmodelforfaultmovementofplateboundary[J].CrustalDeformationandEarthquake,2000,20(2):8～14(inChinese).
[4] 何玉梅,姚振兴.中国台湾南部及其周边岛屿现今地壳形变的位错模型[J].地球物理学报,2002,45(5):638～645.HeYumei,YaoZhenxing.DislocationmodelforcurrentcrustaldeformationinandaroundsouthernTaiwan[J].ChinaChineseJGeophys.,2002,45(5):638～645.
[5] OkadaY.Surfacedeformationduetoshearandtensilefaultsinahalf space[J].BulletinoftheSeismologicalSocietyofAmerica,1985,75(4):1135～1154.
[6] 黄立人,王敏.构造块体的相对运动和应变[J].地壳形变与地震,1999,19(2):17～26.HuangLiren,WangMin.Relativemovementandstrainoftectonicblocks[J].CrustalDeformationandEarthquake,1999,19(2):17～26(inChinese).
[7] 张希,江在森,张晓亮,等.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,2002,22(3):40～45.ZhangXi,JiangZaisen,ZhangXiaoliang,etal.AseismicnegativedislocationinversionofrecenthorizontalcrustmovementinNorthChina[J].JofGeodesyandGeodynamics,2002,22(3):40～45(inChinese).
[8] 张希,江在森,王琪,等.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[J].地震学报(2003年待刊).ZhangXi,JiangZaisen,Wangqi,etal.Aseismicnegativedislocationmodelanddeformationanalysisofhorizontalcrustalmovementduring1999～2001inthenortheastmarginofQinghai Tibetblock[J].ActaSeismologicaSinica(willbepublishedin2003)
[9] 江在森,张希,崔笃信,等.青藏块体东北缘近期水平运动与变形[J].地球物理学报,2001,44(5):636～644.JiangZaisen,ZhangXi,CuiDuxin,etal.RecenthorizontalmovementanddeformationinthenortheastmarginofQinghai Tibetblock[J].ChineseJGeophys,2001,44(5):636～644.
[10] 江在森,马宗晋,张希,等.青藏块体东北缘水平应变场与构造变形分析[J].地震地质,2001,23(3):337～345JiangZaisen,MaZongjin,ZhangXi,etal.AnalysisofrecenthorizontalcrustalstrainfieldandtectonicdeformationinthenortheastmarginofQinghai Tibetblock[J].SeismologyandGeology,2001,23(3):337-346(inChinese).
[11] 张希,江在森,王双绪,等.青藏块体及周缘潜在震源与强震关系研究[J].大地测量与地球动力学,2003,23(1):35～41.ZhangXi,JiangZaisen,WangShuangxu,etal.StudyonrelationshipofpotentialhypocentertostrongearthquakesinQinghai Tibetblockanditsmargins[J].JofGeodesyandGeodynamics,2003,23(1):35～41(inChinese).
[12] 申重阳,吴云,杨少敏,等.华北地块内部主要断层运动模型的GPS数据反演分析[J].地壳形变与地震,2001,21(4):33～42.ShenChongyang,WuYun,YangShaomin,etal.GPSdatainversionandanalysisofmainfaultmovementmodelinsideNorthChinaplate[J].CrustaldeformationandEarthquake,2001,21(4):33～42(inChinese).
[13] 张希,江在森,张四新.借助最小二乘配置整体解算地壳视应变场[J].地壳形变与地震,1998,18(2),57～62.ZhangXi,JiangZaisen,ZhangSixin.Wholecalculationofthecristalapparentstrainfieldwiththeaidoftheleastsquarecollocation[J].CrustaldeformationandEarthquake,1998,18(2):57～62(inChinese).
[14] 张希,江在森.用最小二乘配置获得地形变应变场动态图像的几个问题研究.地壳形变与地震,1999,19(3):32～39.ZhangXi,JiangZaisen.Studyonsomequestionsofdynamicpicturesofcrustaldeformationandstrainfieldsobtainedbytheleastsquarecollocation[J].CrustaldeformationandEarthquake,1999,19(3):32～39(inChinese).
[15] 江在森,张希,陈文胜,等.地形变资料求解应变值尺度相对性问题研究[J].地震学报,2000,22(4):352～359JiangZaisen,ZhangXi,ChenWensheng,etal.Studyonscaledependenceofstrainvalueobtainedfromcrustaldeformationdata[J].ActaSeismologicaSinica,2000,22(4):352～359.
[16] 江在森,张希,王双绪,等.昆仑山口西Ms8.1地震前区域构造变形背景[J].中国科学(d辑)(2003年待刊)JiangZaisen,ZhangXi,WangShuangxu,etal.RegionaltectonicdeformationbackgroundbeforeMs8.1earthquakeonthewestofKunlunmountainpass[J].ScienceinChina(SeriesD)(willbepublishedin2003)
[17] 徐菊生,赖锡安,卓力格图,等.中国大陆西部地区现今的块体运动[J].地壳形变与地震,2000,20(2):15～23XuJusheng,LaiXi'an,Zhuo Li
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