岫岩M_S5.4地震前后S波分裂研究
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摘要
利用辽宁数字地震台网的营口台的三分向数字化地震资料,研究了1999年岫岩MS5.4地震前后S波分裂特征。结果表明:(1)延迟时间大部分在0.9~7.2ms/km范围内,平均4.23ms/km;(2)震前快S波的优势偏振方向为N51°~88°E,平均N58.66°E;震后S波的偏振方向主要集中在N1°W~N2°E和N55°~84°E范围内,平均偏振角为近NS向和N68.13°E。NE的偏振方向与震源应力场的主压应力方向N70°E接近,由此推测1999年岫岩MS5.4地震的S波分裂是震源应力场引起的介质各向异性的结果。
The characteristics of S-wave fission around Xiuyan Ms5.4 eartquake in 1999 are studied by using 3D digital earthquake data of Yingkou station in Liaoning digital earthquake network.The results show:①Delay time of most earthquakes is from 0.9ms/km to 7.2ms/km and the average is 4.23ms/km;②Before the earthquake,the polarization direction of fast S-wave is from N51° to 88° E and the average is N58.66° E;After the earthquake,the polarization direction of fast S-wave is concentrated on N1W°～N2° E and N55°～84° E,the average is NS and N68.13° E.And the NE polarization direction is closed to N70° E which is the principal pressure stress direction in this focal stress field.So,it is deduced that the S-wave fission of Xiuyan Ms5.4 earthquake in 1999 is the result of medium anisotropy caused by the focal stress field.
The characteristics of S-wave fission around Xiuyan Ms5.4 eartquake in 1999 are studied by using 3D digital earthquake data of Yingkou station in Liaoning digital earthquake network.The results show:①Delay time of most earthquakes is from 0.9ms/km to 7.2ms/km and the average is 4.23ms/km;②Before the earthquake,the polarization direction of fast S-wave is from N51° to 88° E and the average is N58.66° E;After the earthquake,the polarization direction of fast S-wave is concentrated on N1W°～N2° E and N55°～84° E,the average is NS and N68.13° E.And the NE polarization direction is closed to N70° E which is the principal pressure stress direction in this focal stress field.So,it is deduced that the S-wave fission of Xiuyan Ms5.4 earthquake in 1999 is the result of medium anisotropy caused by the focal stress field.
引文
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