【摘要】 利用辽宁遥测数字地震台网营口台的地震波形资料,采用高原等剪切波分裂SAM分析方法,对1999年11月29日辽宁省岫岩MS5.9(ML5.3)地震前后的地震序列进行了剪切波分裂分析.通过对营口台的资料分析表明,快剪切波优势偏振方向为ENE--WSW向,与该地区主压应力方向一致,也与华北区域构造应力场方向一致;平均慢剪切波时间延迟在岫岩地震前显示增加,可能反映了震前的应力积累过程.营口台的快剪切波优势偏振方向还与小地震活动空间分布走向一致,与活动断层走向相关.快剪切波偏振的月平均变化直方图也显示,地震前两个月快剪切波偏振方向似乎也有变化,但这个现象还需要更多资料的证实.更多还原

【Abstract】 Using seismic waveform data recorded at station Yingkou (YK) of Liaoning Telemetry Digital Seismic Network, this paper studied the characteristics of shear-wave splitting before and after the Xiuyan MS5.9 (ML5.3) earthquake on November 29, 1999, with the SAM method (Gao et al). The result shows that predominant polarization of fast shear-waves at YK is in direction of ENE--WSW, consistent with the direction of regional principal compressive stress and also consistent with the direction of regional tectonic stress field in North China. The time-delays increased before the Xiuyan earthquake, indicating stress accumulation before the mainshock. Predominant polarization of fast shear-waves at YK is also related to the spatial distribution of small earthquakes and correlated to the fault strike. The histogram of monthly average polarizations of fast shear-waves shows that the polarization of fast shear-waves seems to have changed from two months before the mainshock, but this needs to be verified with more data.更多还原