【摘要】 根据南通市及周边地震台2001-2011年的波形资料,拾取P波初动,应用综合震源机制解法研究了该地区的地壳应力场方向,在本研究中使用了1391个P波初动.而在计算中,我们根据每个地震离南通市距离的不同赋予其P波初动符号不同的权重,加权后P波初动数据的总权重为289.39,加权后的初动符号矛盾比为0.37.研究结果表明:主压应力轴方位和倾角分别为97°和53°;中间应力轴方位和倾角分别为196°和7°;主张应力轴方位和倾角分别为291°和36°.只搜索到一个最优解,说明研究数据的分辨率还是相当高的.南通市位于华北应力分区和华南应力分区之间,所得主压应力方位介于华北应力分区主压应力场方向NEE-EW和华南应力分区主压应力方向NWW之间,这体现了应力场的连续性.此外,主压应力轴倾角较大,其它两个应力轴倾角相对较小,和穿过南通市的NNW向正断性南通—上海断裂相吻合,反映了本研究结果的可靠性.更多还原

【Abstract】 The P-wave first motion polarity was picked up according to the seismic waveform data,which was recorded by the seismic station of Nantong city and its adjacent area in 2001-2011,the crustal stress direction of Nantong was calculated by using the composite focal mechanism method.1391 P wave first motion data were used,we give each data a weight according to the distance between the earthquake and Nantong city,the total weight of the P wave first motion data is 289.39 after weighted,the P wave first motion contradictory ratio is 0.37 after weighted.The study results show that,the azimuth and dip angle of principal compressive stress axis are 97° and 53°,the azimuth and dip angle of middle principal stress axis are 196° and 7°,the azimuth and dip angle of principal extensional stress axis are 291° and 36°,respectively.Just one optimal solution was searched,shows that the resolution of research data is very high.The geographical location of Nantong city is between the tectonic stress region of north China and the tectonic stress region of south China,the azimuth of principal compressive stress axis we obtained is between the azimuth(NEE-EW) of principal compressive stress axis of north China stress region and the azimuth(NWW) of principal compressive stress axis of south China stress region,that reflects the continuity of the stress field.The dip angle of principal compressive stress axis is large,and the dip angle of the other two principal stress axes is relatively small,which is consistent with the normal fault of Nantong-Shanghai fault,the Nantong-Shanghai fault is through Nantong city,that reflect the reliability of our results.更多还原