COMPARISON BETWEEN EARTHQUAKE MAGNITUDES DETERMINED BY CHINA SEISMOGRAPH NETWORK AND US SEISMOGRAPH NETWORK (II): SURFACE WAVE MAGNITUDE

Abstract

By using orthogonal regression method, a systematic comparison is made between surface wave magnitudes determined by Institute of Geophysics of China Earthquake Administration (IGCEA) and National Earthquake Information Center of US Geological Survey (USGS/NEIC) on the basis of observation data collected by the two institutions between 1983 and 2004. A formula is obtained which reveals the relationship between surface wave magnitudes determined by China seismograph network and US seismograph network. The result shows that, as different calculation formulae and observational instruments are used, surface wave magnitude determined by IGCEA is generally greater by 0.2 than that determined by NEIC: for M = 3.5~4.5 earthquakes, it is greater by 0.3; for M = 5.0-6.5 earthquakes, it is greater by 0.2; and for M ≥ 7.0 earthquakes, it is greater by no more than 0.1.