Abstract:
After the Lushan
MW6.7(
MS7.0) earthquake on 20 April, 2013 in Sichuan Province, this paper revised the earthquake parameters rapidly issued by China Earthquake Networks Center (CENC), based on the data from 97 stations of China National Seismic Network. The results are: the origin time of the earthquake is 08:02:47.5 Beijing time (00:02:47.5 UTC), the epicenter is located at (30.30°N, 102.99°E) and the focal depth is 17 km; the surface wave magnitude of the earthquake is
MS7.0, the short period body wave magnitude is
mb6.0 and the moderate-long period body wave magnitude is
mB7.0. The focal mechanisms are calculated by waveform inversion and the two nodal planes of the best double couple solution are: for the nodal plane Ⅰ strike 17°/dip 48°/slip 80°, and strike 212°/dip 43°/slip 101° for the nodal plane Ⅱ; the moment magnitude is
MW6.7. In addition, in view of the fact that the magnitude issued by CENC is
MS7.0, while that by USGS/NEIC is
MW6.6, so it is suggested that China should issue
MW as the preferred magnitude so as to make the magnitude report in accordance with international convention.