松软覆盖层对隐伏断层带围陷波的影响研究
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摘要
利用二维非均匀介质地震波传播的伪谱和有限差分混合方法,通过数值计算,讨论了松软覆盖层对隐伏断层带围陷波特征的影响。在没有覆盖层的情况下,围陷波振幅和围岩上相比明显增加,持续时间变长。覆盖层造成围岩上地面运动振幅增大,围陷波的部分能量传播到覆盖层中,使得围陷波的能量变小。随着覆盖层厚度增加,围陷波的振幅越来越小,和围岩上的振幅越来越接近。在松软沉积层的地区开展隐伏断层带的围陷波观测,需要考虑覆盖层厚度的影响。
We applied 2D Fourier pseudospectral and finite difference hybrid method for heterogeneous medium to simulate the propagation of fault trapped seismic waves,and discussed the effects of overburden soft layer on trapped seismic waves.We found that for a fault without overburden layer,the amplitudes of trapped waves have larger amplitude and longer duration compared with those on the surrounding bedrock.Presence of overburden soft layer enhances the amplitude on the surrounding bedrock.Some energy of the trapped waves pro-pagates into the overburden layer and the energy of the trapped waves decreases.With the increasing of the thickness of overburden layer,amplitudes of the trapped waves decrease and become similar to those on the surrounding bedrock.The thickness of overburden soft layer is a key factor that should be considered when fault trapped seismic wave observation is carried out in areas with soft sedimentary layers.
We applied 2D Fourier pseudospectral and finite difference hybrid method for heterogeneous medium to simulate the propagation of fault trapped seismic waves,and discussed the effects of overburden soft layer on trapped seismic waves.We found that for a fault without overburden layer,the amplitudes of trapped waves have larger amplitude and longer duration compared with those on the surrounding bedrock.Presence of overburden soft layer enhances the amplitude on the surrounding bedrock.Some energy of the trapped waves pro-pagates into the overburden layer and the energy of the trapped waves decreases.With the increasing of the thickness of overburden layer,amplitudes of the trapped waves decrease and become similar to those on the surrounding bedrock.The thickness of overburden soft layer is a key factor that should be considered when fault trapped seismic wave observation is carried out in areas with soft sedimentary layers.
引文
[1]刘明军,李松林,张先康,等.海原断裂带断层通道波观测与破碎带宽度[J].物探与化探,2004,28(6):549-552.
[2]楼海,王椿镛,丁志峰,等.昆仑山断层围陷波的分析和研究[J].地球物理学报,2006,49(3):788-796.
[3]李松林,张先康,樊计昌.利用断层围陷波研究昆仑山口西8.1级地震破裂面[J].地震学报,2005,27(1):42-50.
[4]姚志祥,王椿镛,楼海.利用基于围陷波波形相关的网格搜索法确定昆仑山断裂带结构参数[J].地球物理学报,2010,53(5):1 167-1 172.
[5]潘纪顺,张先康,姚志祥,等.库赛湖—玛沁断裂带东段断层通道波的观测研究[J].大地测量与地球动力学,2009,29(4):21-25.
[6]李松林,赖晓玲,何加勇,等.汤西断裂的断层围陷波初步研究[J].地震地质,2007,29(2):354-362.
[7]赖晓玲,李松林.汶川地震区平通镇断层围陷波探测[J].大地测量与地球动力学,2008,28(6):6-10.
[8]魏星,王彦宾,陈晓非.模拟地震波场的伪谱和高阶有限差分混合方法[J],地震学报,2010,32(4):392-400.
[9]Jahnke G,Igel H,Ben-Zion Y.Three-dimensionalcalculations of fault-zone-guided waves in variousirregular structures[J].Geophys.J.Int.,2002,151:416-426.
[2]楼海,王椿镛,丁志峰,等.昆仑山断层围陷波的分析和研究[J].地球物理学报,2006,49(3):788-796.
[3]李松林,张先康,樊计昌.利用断层围陷波研究昆仑山口西8.1级地震破裂面[J].地震学报,2005,27(1):42-50.
[4]姚志祥,王椿镛,楼海.利用基于围陷波波形相关的网格搜索法确定昆仑山断裂带结构参数[J].地球物理学报,2010,53(5):1 167-1 172.
[5]潘纪顺,张先康,姚志祥,等.库赛湖—玛沁断裂带东段断层通道波的观测研究[J].大地测量与地球动力学,2009,29(4):21-25.
[6]李松林,赖晓玲,何加勇,等.汤西断裂的断层围陷波初步研究[J].地震地质,2007,29(2):354-362.
[7]赖晓玲,李松林.汶川地震区平通镇断层围陷波探测[J].大地测量与地球动力学,2008,28(6):6-10.
[8]魏星,王彦宾,陈晓非.模拟地震波场的伪谱和高阶有限差分混合方法[J],地震学报,2010,32(4):392-400.
[9]Jahnke G,Igel H,Ben-Zion Y.Three-dimensionalcalculations of fault-zone-guided waves in variousirregular structures[J].Geophys.J.Int.,2002,151:416-426.
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