近场P波频谱分布及震级确定方法

通过研究国内12个4~7级地震的近场P波前3秒加速度波形记录的频谱分布, 我们发现, 对于较大的地震, 近场通常接收到的低频信息比较稳定, 尤其是1 Hz以下的信号。 通过对3秒初至P波震相加速度记录的低频窄带滤波及对传统震级公式的改造, 我们得到了4个低频段的震级计算公式M₁, M₂, M₃, M₄及预警震级计算结果M_n。 将其应用到日本13个4~7级的地震中, 并对比目前主流Pd震级计算方法, 我们的结果离散度与可靠性更好。 因此, 可认为我们得到的震级公式是较可靠的一种估算近场震级的方法, 并且可以应用到地震预警中。

Near-field P-wave Frequency Spectrum Distribution and Magnitude Estimation for Early Warning

We selected 12 regional earthquakes with 4<M<7 in China to analyze the frequency spectrum of near-field P-wave acceleration for the first 3 seconds, and found out that the low-frequency information in the near field, especially lower than 1Hz, is more stable. Through processing the first 3-second near-field P-wave acceleration using low frequency narrow bandwidth filters, and redesigning the traditional magnitude formula, we obtained four magnitude calculation formulas M₁、M₂、M₃、M₄ in low frequency band and the magnitude estimation in earthquake early warning M_n. We apply the method and results to 13 earthquakes from K-Net catalog with 4<M<7 in Japan, and the result shows that the method has a better degree of dispersion and is more reliable, comparing with P_d magnitude estimation method which is widely used now. The magnitude calculation formulas in this paper are more reliable in estimating near-field magnitude and can be applied to earthquake early warning system.