Abstract: The New National Standard (NNS) of earthquake magnitude have been used in the determination of earthquake magnitude. To estimate the magnitude impact of the NNS on the moderate-strong shallow earthquakes in quick report, the differences between the magnitudes of broad band surface wave (M_S(BB)) and the magnitudes of old rapid determination are systematically analyzed based on the rapid report catalogue of M≥5.0 earthquakes in China mainland from 2001 to 2017. In addition, we make a comparative analysis on the M_S(BB) , M_S(NEIC), M_W(CENC) and M_W(GCMT). The results show that the NNS magnitudes are basically consistent with that of the NEIC for M≥6. The frequencies of earthquakes with M≥5 and M≥6 decrease to about 60% and 80% of the original data, but difference is little when M≥6.5. The moment magnitudes estimated by China mainland are consistent with the international results. Because the earthquake magnitude is released using the moment magnitude in world and there is systematical difference between the moment magnitude and surface wave magnitude. Thus, we should take the moment magnitude as the rapid determination result in China to consistent with the international results. It may further decrease the frequency of M6 and M7 earthquakes.

Key words: Earthquake rapid report, Surface wave magnitude, Moment magnitude, Earthquake frequency