玉树和汶川地震前后区域水平形变的空间分布
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摘要
以1999—2007年和2009—2010年两个时间段的GNSS观测资料为基础,借助于多核函数解析、滤波和应变场的无偏算法以及区域无旋转基准,在运动场连续变化的条件下获得了玉树MS7.1和汶川MS8.0地震前后青藏高原东南地域运动与形变场,并得到如下基本认知:①玉树和汶川地震前震源区构造活动在空间和较长时间上明显弱化,最大正应变和最大剪切应变均处在区域构造活动的最低水平。②与地震破裂相应的旋剪形变最大部位既不位于震源区也不远离震源区,似乎存在某种协调有序活动,玉树地震发震构造断裂带基本上处在区域右旋活动与左旋活动的过渡区上,而左旋活动最大条带却为平行于该断裂带且相距约150km的东北构造活动区内;汶川地震发震构造断裂虽处在右旋活动的龙门山断裂带上,但右旋活动最大条带为平行于该断裂带且相距约200km的西北活动区内。③玉树地震震时较大水平形变的范围较小,汶川地震震后水平形变仍较突出。④理塘—德巫断裂带的北段及周边地区应给予关注,面应变为象限分布图像,最大正应变和最大剪切应变均显示闭锁的迹象。
Based on GNSS observation(from 1999 to 2007,and from 2009 to 2010) and continuous variation of deformation field,this study employed filtering and analysis of multi-kernel function and an unbiased algorithm of strain field to obtain movement and deformation field of the southeastern of Qinghai-Tibet Plateau before and after the MS7.1 Yushu and MS8.0 Wenchuan earthquakes.The observations showed: ① Tectonic activities of seismic source were significantly weakened at spatial and relative long time level before the Yushu and Wenchuan earthquake.The maximum positive strain and shear strain fell to the lowest level of regional tectonic activities.② Spin shear deformation corresponding to the earthquake rupture was neither in nor far from the seismic source region,and there seemed an orderly coordinated action.The tectonic fault zone of Yushu earthquake was in the intermediate of regional right-lateral and left-lateral movements,while the largest stripe of left-lateral movement was 150 km away from the northeast of tectonic activity region,paralleling with the fault zone.Although structural fracture of Wenchuan earthquake was in the Longmen Mountain fault zone of right-lateral movement,the largest band of right-lateral movement was paralleled with this fault zone and in the northwestern activity zone with 200 km distance.③ The range of large co-seismic horizontal deformation of the Yushu earthquake was actually small,while the post-seismic horizontal deformation of the Wenchuan earthquake remains significant.④ The North and the surrounding of Litang-Dewu fault zone should be given more attentions because plane-strain was presented in the image of quadrant distribution,and both the maximum positive strain and maximum shear strain were showing sign of being locked.
Based on GNSS observation(from 1999 to 2007,and from 2009 to 2010) and continuous variation of deformation field,this study employed filtering and analysis of multi-kernel function and an unbiased algorithm of strain field to obtain movement and deformation field of the southeastern of Qinghai-Tibet Plateau before and after the MS7.1 Yushu and MS8.0 Wenchuan earthquakes.The observations showed: ① Tectonic activities of seismic source were significantly weakened at spatial and relative long time level before the Yushu and Wenchuan earthquake.The maximum positive strain and shear strain fell to the lowest level of regional tectonic activities.② Spin shear deformation corresponding to the earthquake rupture was neither in nor far from the seismic source region,and there seemed an orderly coordinated action.The tectonic fault zone of Yushu earthquake was in the intermediate of regional right-lateral and left-lateral movements,while the largest stripe of left-lateral movement was 150 km away from the northeast of tectonic activity region,paralleling with the fault zone.Although structural fracture of Wenchuan earthquake was in the Longmen Mountain fault zone of right-lateral movement,the largest band of right-lateral movement was paralleled with this fault zone and in the northwestern activity zone with 200 km distance.③ The range of large co-seismic horizontal deformation of the Yushu earthquake was actually small,while the post-seismic horizontal deformation of the Wenchuan earthquake remains significant.④ The North and the surrounding of Litang-Dewu fault zone should be given more attentions because plane-strain was presented in the image of quadrant distribution,and both the maximum positive strain and maximum shear strain were showing sign of being locked.
引文
[1]张军龙,陈长云,胡朝忠,等.玉树MS7.1地震地表破裂带及其同震位移分布[J].地震,2010,30(3):1-12.
[2]张永生,马寅生,胡道功,等.玉树地震地表破裂调查与灾后重建避让选址研究[J].地质学报,2010,84(5):593-605.
[3]刘超,许力生,陈运泰.2010年4月14日青海玉树地震快速矩张量解[J].地震学报,2010,32(3):366-368.
[4]张勇,许力生,陈运泰.2010年4月14日青海玉树地震破裂过程快速反演[J].地震学报,2010,32(3):361-365.
[5]付碧宏,时丕龙,王萍,等.2008年汶川地震断层北川段的几何学与运动学特征及地震地质灾害效应[J].地球物理学报,2009,52(2):485-495.
[6]王敏.基于GPS同震位移场约束反演2008年5.12汶川大地震破裂空间分布[J].地球物理学报,2009,52(10):2 519-2 526.
[7]国家重大科学工程“中国地壳运动观测网络”项目组.GPS测定的2008年汶川MS8.0地震的同震位移场[J].中国科学,2008,38(10):1195-1206.
[8]江在森,方颖,武艳强,等.汶川8.0级地震前区域地壳运动与变形动态过程[J].地球物理学报,2009,52(2):505-518.
[9]李延兴,张静华,周伟,等.汶川8.0级地震孕育的机制与动力学问题[J].地球物理学报,2009,52(2):519-530.
[10]郭良迁,李延兴,胡新康,等.中国大陆地壳运动与汶川8.0级地震孕育的关系[J].地球物理学报,2009,52(2):531-537.
[11]杜芳,闻学泽,张培震,等.2008年汶川8.0级地震前横跨龙门山断裂带的震间形变[J].地球物理学报,2009,52(11):2729-2738.
[12]杨国华,武艳强,杨博,等.应变计算与分析的若干问题及有关偏差的修正[J].大地测量与地球动力学,2010,30(4):59-63.
[13]杨博,张风霜,占伟.水平运动场的滤波试验与应变计算[J].大地测量与地球动力学,2010,30(5):106-112.
[14]杨博,董运鸿,张风霜,等.形变强度指数及其地壳变形分析中的应用[J].地震,2010,30(2):112-120.
[15]杨国华,江在森,武艳强,等.中国大陆整体无净旋转基准及其应用[J].大地测量与地球动力学,2005,25(4):6-10.
[16]杨国华,桂昆长,巩曰沐,等.板内强震蕴震过程中地形变图象及模式的研究[J].地震学报,1995,17(2):156-163.
[17]刘序俨,黄声明,林岩钊.地形变旋转量的探讨[J].大地测量与地球动力学,2010,30(5):57-63.
[18]杨国华,张晓东,张风霜,等.昆仑山口西8.1级地震震后中国西部地壳水平位移场的变化特征[J].地震研究,2008,31(1):77-81.
[2]张永生,马寅生,胡道功,等.玉树地震地表破裂调查与灾后重建避让选址研究[J].地质学报,2010,84(5):593-605.
[3]刘超,许力生,陈运泰.2010年4月14日青海玉树地震快速矩张量解[J].地震学报,2010,32(3):366-368.
[4]张勇,许力生,陈运泰.2010年4月14日青海玉树地震破裂过程快速反演[J].地震学报,2010,32(3):361-365.
[5]付碧宏,时丕龙,王萍,等.2008年汶川地震断层北川段的几何学与运动学特征及地震地质灾害效应[J].地球物理学报,2009,52(2):485-495.
[6]王敏.基于GPS同震位移场约束反演2008年5.12汶川大地震破裂空间分布[J].地球物理学报,2009,52(10):2 519-2 526.
[7]国家重大科学工程“中国地壳运动观测网络”项目组.GPS测定的2008年汶川MS8.0地震的同震位移场[J].中国科学,2008,38(10):1195-1206.
[8]江在森,方颖,武艳强,等.汶川8.0级地震前区域地壳运动与变形动态过程[J].地球物理学报,2009,52(2):505-518.
[9]李延兴,张静华,周伟,等.汶川8.0级地震孕育的机制与动力学问题[J].地球物理学报,2009,52(2):519-530.
[10]郭良迁,李延兴,胡新康,等.中国大陆地壳运动与汶川8.0级地震孕育的关系[J].地球物理学报,2009,52(2):531-537.
[11]杜芳,闻学泽,张培震,等.2008年汶川8.0级地震前横跨龙门山断裂带的震间形变[J].地球物理学报,2009,52(11):2729-2738.
[12]杨国华,武艳强,杨博,等.应变计算与分析的若干问题及有关偏差的修正[J].大地测量与地球动力学,2010,30(4):59-63.
[13]杨博,张风霜,占伟.水平运动场的滤波试验与应变计算[J].大地测量与地球动力学,2010,30(5):106-112.
[14]杨博,董运鸿,张风霜,等.形变强度指数及其地壳变形分析中的应用[J].地震,2010,30(2):112-120.
[15]杨国华,江在森,武艳强,等.中国大陆整体无净旋转基准及其应用[J].大地测量与地球动力学,2005,25(4):6-10.
[16]杨国华,桂昆长,巩曰沐,等.板内强震蕴震过程中地形变图象及模式的研究[J].地震学报,1995,17(2):156-163.
[17]刘序俨,黄声明,林岩钊.地形变旋转量的探讨[J].大地测量与地球动力学,2010,30(5):57-63.
[18]杨国华,张晓东,张风霜,等.昆仑山口西8.1级地震震后中国西部地壳水平位移场的变化特征[J].地震研究,2008,31(1):77-81.
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