Shear-wave splitting in the crust in Eastern Songpan-Garzê block, Sichuan-Yunnan block and Western Sichuan Basin
Shear-wave splitting in the crust in Eastern Songpan-Garzê block, Sichuan-Yunnan block and Western Sichuan Basin
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发表时间：
2013
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通讯作者：
Shi Yu
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作者：
Shi Yu
青藏高原东部有松潘-甘孜地块东部、川滇地块和四川盆地西部，是我国地震活动较强的地区之一。利用四川区域数字地震台网记录的2000年1月至2010年4月的地震资料，采用剪切波分裂分析方法(SAM)计算了该地区44个台站以下的快剪切波偏振和慢剪切波时延。由于区域主压应力和局部地质构造的影响，研究结果表明：快剪切波偏振的空间分布具有局部化特征，龙门山断裂带东北段和西南段的优势PFS分别表现为北东向和西北向，川滇地块西北部和东南部的PFS几乎呈东西和西北向分布，青川断裂带北侧和南侧的剪切波分裂参数的优势方向分别为近南北向和近东西向，北侧的时延大于南侧。这一研究表明，剪切波分裂参数的局部化分布可能是复杂的地质构造和活动断裂的几何形状造成的。
In eastern Tibetan Plateau,there are eastern Songpan-Garze block,Sichuan-Yunnan block and western Sichuan Basin,where is one of the areas with strong seismic activity in China.In this study,the polarization of fast shear waves(PFS) and time delay of slow shear-wave beneath the 44 stations in this area were computed using shear-wave Splitting Analysis Method(SAM) based on the seismic data during January 2000 to April 2010,recorded by Sichuan Regional Digital Seismic Network.Due to the impact of the regional principal compressive stress and local geological structure,the spatial distribution of polarization of the fast shear-wave shows the localized characteristic.The dominant PFS beneath the northeast and southwest segment of Longmenshan fault belt exhibits the North-East and North-West direction,respectively.PFS beneath the northwest and southeast part of the Sichuan-Yunnan block shows nearly East-West and North-Northwest direction,respectively.The dominant direction of PFS beneath the north and south side of Qingchuan fault respectively are nearly North-South and East-West.The time delay beneath north side is larger than that in the south side of Qingchuan fault.This study suggests that the localized distribution of shear-wave splitting parameter could be caused by complex geological structure and the geometry of active faults.