鄂尔多斯块体北缘呼包鄂地区岩石圈各向异性初步研究

A preliminary study on the anisotropy of the lithosphere in Hohhot-Baotou-Ordos area

选取呼包鄂区域11个宽频带地震台站记录的156个远震事件,使用剪切波分裂软件,对所选远震波形数据进行处理,求取并分析震中距85°—110°范围内同时被各地震台站记录的远震震相SKS的各向异性参数,即快波偏振方向及慢波到时差,结果表明:呼包鄂区域地下深层介质存在各向异性,快波偏振优势方向为ESE,慢波延迟时间为0.87—1.74 s,平均延迟1.26 s,推断该区地下深层介质存在各向异性层,层厚100—200 km,平均层厚约145 km。

156 teleseismic events recorded at 11 broadband seismic stations in Hohhot-Baotou-Ordos area are selected.The seismic records of selected teleseismic events are processed by shear wave splitting software.The anisotropic parameters of SKS waves recorded by multiple stations with an epicentral distance between 85°—110°,i.e.,the arrival time differences between fast wave and slow wave,are obtained.The analysis shows that the fast axis in Hohhot-Baotou-Ordos area is oriented ESE.The delay time of slow wave is 0.87-1.74 s and the average time delay is 1.26 s.The thickness of the anisotropic layer in this area is estimated to be 100-200 km,with an average of about 145 km.