Comparative study on the energy-moment ratio between the 2013 Minzhang earthquake and the 2014 Jinggu earthquake

The moment magnitude of the Minzhang earthquake in 2013 and the Jinggu earthquake in 2014 are both M-w 6. 1, but the former caused significantly larger area of the same isoseismals than the latter. The isoseismals of ground shaking is closely related to the high-frequency components of the seismic waves radiated during the source rupture. The source spectra of these two earthquakes and the energy-moment ratio which reflect the source characteristics, are measured and analyzed systematically. The results show that the seismic moment released by the Minzhang earthquake and Jinggu earthquake have little difference, 1. 6 X 10(18) Nm and 1. 8 X 10(18 )Nm, respectively. The seismic moment of the Minzhang earthquake is slightly smaller than the seismic moment of the Jinggu earthquake, but the radiated energy of the Minzhang earthquake and Jinggu earthquake are 1. 3 X 10(14)J and 0. 6 X 10(14)J, respectively. Therefore the energy-moment ratio of the Minzhang earthquake (8. 1 X 10(5)) is about 2. 5 times that of the Jinggu earthquake (3. 3 X 10(5)). Accordingly, the apparent stress and the stress drop of the Minzhang earthquake were significantly greater than that of the Jinggu earthquake. In addition, the modeling results of two earthquakes show that the high-frequency attenuation of source spectra are both consistent with ca' model. The radiated energy results calculated by the theoretical formula alone account for about 54% and 50% of the actual results respectively, and the difference of the theoretical radiated energy results between two earthquakes is still about 2. 3 times. The significant difference of source rupture characteristics lead to different energy radiated per unit seismic moment. Minzhang earthquake has larger energy-moment ratio than the Jinggu earthquake, which is one of the important reasons resulting that the Minzhang earthquake is of larger isoseismal area than that of the Jinggu earthquake with the same isoseismal.