新疆及邻区体波震级初步分析研究

Preliminary Analysis and Research of Body Wave Magnitude in Xinjiang and the Adjacent Area

摘要:

依据《地震震级的规定（GB 17740—2017）》，分析了2009—2017年新疆地震台网所记录的新疆及邻区476次中深源地震事件，测定了13601个m_b（短周期体波震级）和12035个m_B（BB）（宽频带体波震级）的数据样本，回归分析m_b和m_B（BB）得到回归方程及量规函数，结果显示m_b和m_B（BB）相关系数为0.966，表明两者显著相关。因此，建议对于中强型中深源地震可以直接从原始速度型宽频带数字地震记录上测定长周期体波震级m_B（BB），提高地震速报测定的速度和精度。通过震级偏差统计和台站场地响应计算，分析新疆地震台网中的XKR、HTA、ATS和KSZ等地震台站震级偏差较大的原因为砂岩、灰岩、砂土层等类型的台基放大了场地响应，说明台基类型对体波震级偏差的影响较大。与NEIC测定的体波震级对比时，发现新疆地震台网测定体波震级平均偏大0.42级，且偏差随着震源深度的增加有增大的趋势。

Abstract:

According to the general standard of earthquake magnitude(GB17740-2017), we analyzed 476 the intermediate and deep-focus earthquakes in Xinjiang and the adjacent area from 2009 to 2017. Then we got 13601 m_b samples, 12035 m_B(BB)samples, the regression equations, and the calibration function of m_b and m_B(BB).Through magnitude residual statistical analysis and by calculating the station site response, we concluded that the station bedrocks magnify the station site response, which causes the large magnitude offsets, such as sandstone and limestone and sand soil, So the magnitude offsets of XKR, HTA, ATS and KSZ are relatively large. By comparing with the body wave magnitude from NEIC, we found that magnitudes from our results are greater than that from NEIC's by 0.42. Moreover, the offsets tend increasingly with the increase of focal depth.