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提出了一种利用加速度记录图中的体波初动与高频振幅峰值的到时差(T_(op))测量地震震级M的简单方法。用这种方式测量,我们发现,对于5≤M_W≤7的地震M_W与2logT_(op)成正比,如果T_(op)与震源尺度成正比并且应力降量级不变,这与理论结果相一致。使用高频(>2Hz)数据,M_W与M_(T_(op))(根据T_(op)估计的M)之间的均方根(rms)残差约为0.5个震级单位。在2~16Hz通带中高频数据的均方根残差,均匀地小于从较低频数据获得的值。T_(op)的值与震中距弱相关,在震中距<200km范围内可以忽略这种相关性。该算法对2011年日本东北地震的回顾性应用,在该地震发震时刻之后120s内做出M9.0的最终震级估算。我们由此得出结论,高频(>2Hz)加速度记录的T_(op)值,在发生特大地震时对地震预警很有价值。
A simple method to measure the earthquake magnitude M by using the arrival time difference (T_ (op)) of the initial wave motion and the peak of high frequency amplitude in the acceleration record is proposed. Measured in this way, we find that the M_W for earthquakes with 5≤M_W≤7 is proportional to 2logT_ (op), which is in agreement with the theoretical result if T op is proportional to the source scale and the stress drop order is constant . Using high frequency (> 2 Hz) data, the root mean square (rms) residual error between M_W and M_ (T_ (op)) (M estimated from T_ (op)) is about 0.5 magnitude units. The root mean square residuals of the high frequency data in the 2-16 Hz passband are uniformly less than the values obtained from the lower frequency data. The value of T_ (op) is related to the weak epicentral distance, and this correlation can be neglected in the epicentral distance <200km. The algorithm is a retrospective application of the 2011 northeast earthquake in Japan to make a final magnitude estimate of M9.0 within 120 seconds after the earthquake onset. We conclude from this that the T op values recorded for high frequency (> 2 Hz) acceleration are valuable for early warning of earthquakes in the event of a very large earthquake.