Energy magnitude determination of moderate-strong earthquakes

This paper, based on the seismic wave attenuation characteristics, explores a method for utilizing broadband seismic waveform data to measure seismic energy E_S and energy magnitude M_e. The energy magnitudes M_e of four overseas and four domestic moderate-strong earthquakes are measured by using broadband teleseismic P waveform data with epicentral distance in the range of 20°−98°. The comparison of surface wave magnitude M_S, moment magnitude M_W and energy magnitude M_e of several earthquakes shows that: surface wave magnitude M_S represents the magnitude of the energy of seismic wave radiating at a fixed frequency; the moment magnitude M_W is closely related to the static structural effects such as the length of fault, the width of fault and the average dislocation amount of the source rupture produced by the earthquake; the energy magnitude M_e reflects source dynamic characteristics and is closely related to the dynamic characteristics of the seismic source. The energy radiated by the earthquake in the form of seismic waves is mainly concentrated near the corner frequency of the source spectrum, so the energy magnitude M_e is more suitable to describe the destructiveness of the earthquake. Therefore, joint determination of surface wave magnitude M_S, moment magnitude M_W and energy magnitude M_e are of great significance for quantifying and evaluating the disasters caused by earthquakes or tsunamis.