Rapid evaluation of radiated seismic energy for great shallow earthquakes from 2014 to 2019

Based on seismic waves’ attenuation characteristics and the one-dimensional velocity model, we conducted a study for the rapid determination of radiated seismic energy E_S and energy magnitude M_e. The seismic recordings obtained from the Global Seismographic Network and China Seismological Digital Network were used to calculate the E_S and M_e of 115 shallow earthquakes with M_W≥6.0 from 2014 to 2019, and the results were compared with M_W and M_e produced by other institutions. The results show the stable M_e can be obtained within half an hour after obtaining the seismic data, and the M_e values of IRIS were consistent with the earthquakes analyzed in this study. The earthquake damage is closely related to the size of energy magnitude M_e, and the devastation that an earthquake can cause is more serious when the energy magnitude M_e is far greater than the moment magnitude M_W. In all types of earthquakes, the efficiency of radiated energy for earthquakes with strike-slip faults is high, with M_e being significantly greater than M_W. Next, by analyzing two M_W6.1 earthquakes occurred in Hualien, Taiwan region on February 4, 2018 and April 18, 2019, it is concluded that two earthquakes with the same source mechanism in similar locations, although they have the same moment magnitude M_W, the energy magnitude M_e vary greatly, close to 0.5. M_W can only obtain the source’s static characteristic, which is closely related to the static tectonic effects such as fault area and average dislocation of rupture caused by earthquakes. In contrast, M_e can provide the source’s dynamic information and objectively evaluate the damage intensity of an earthquake. Therefore, the approach applied in this study can ensure the accuracy of the results and greatly improve the measurement speed of energy magnitude M_e, which is very suitable for a rapid response system. Our research results can provide a reference for the future seismic network to take energy magnitude M_e as daily output magnitude and provide more information for rapid assessment of disasters caused by large earthquakes.