对于M_L、M_WP、m_B等自动速报中常用的震级测定方法,通过模拟2020年1月19新疆伽师6.4级地震和2021年5月21日云南漾濞中强震震群震级的准实时测定过程,分析这3种震级测定方法在震后不同时间产出的震级的准确度及产生震级偏差的原因。此外,通过计算2020年1月1日—2022年7月31日中国大陆发生的56个M4.5以上地震事件的M_L、M_WP、m_B震级,分析这3种方法在中强震震级测定中的稳定性,比较不同测定方法在不同震级段的优劣及适用范围,得到以下几点认识:①使用转换公式将M_L转换为M是造成震级偏差较大的重要原因,M_L不应转换,其值可直接作为中强震自动速报的发布震级; ②对于密集发生的震群,M_WP和m_B易受先前地震尾波或长周期信号的影响,震级偏大,且偏差较大,不宜用作地震自动速报的震级,使用M_L更优; ③在4.5～5.5震级段应使用M_L作为自动速报测定震级; 在5.5～6.5级区间,应使用M_WP或m_B,其中M_WP稳定性更强,测定用时更短; 对于6.5级以上的地震,应优先使用M_WP。

M_L,M_WP and m_B are commonly used methods of magnitude measurement in automatic earthquake rapid reports. In order to analyze the accuracy of these three methods at different times and demonstrate the reasons of deviations,we simulated the quasi-real-time determination process of the magnitude of the M6.4 earthquake in Jiashi,Xinjiang(January 19,2020)and the moderate-strong earthquake swarm in Yangbi,Yunnan(May 21,2021). By calculating the M_L,M_WP and m_B  magnitudes of 56 earthquake events with M4.5 and above occurred in mainland China from January 1,2020 to July 31,2022,we analyze the stability of these three methods in the determination of moderate-strong earthquake magnitude,after comparing their own benefits and applicability study in different magnitude section. Our results showed that:① Using the conversion relationship converting M_L to M is an important reason for the large deviation. M_L should not be converted,and its value can be directly used as the published magnitude of the automatic quick reports in moderate and strong earthquake events;② For densely occurring earthquake swarms,M_WP and m_B are easily affected by the previous coda wave or long-period signal,resulting in large magnitude and large deviation,so it is not suitable to be used as the magnitude of the automatic rapid reports,but M_L is better;③ In the 4.5～5.5 magnitude range,M_L should be used to measure the magnitude;in the 5.5～6.5 magnitude range,both M_WP or m_B  are good,but M_WP is more stable and time-saving for the earthquakes. For magnitudes above 6.5,M_WP has the better effect and should be applied.

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中国地震台网中心青年科技基金(QNJJ2020002)资助