中国地震台网与美国地震台网测定震级的对比(Ⅱ)——面波震级

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

采用正交回归方法，利用中国地震局地球物理研究所（IGCEA）和美国地质调查局国家地震信息中心（USGS／NEIC）1983-2004年的观测资料，对这两个机构测定的面波震级进行了系统的比较，得到了中国地震台网与美国地震台网面波震级之间的关系式．结果表明，由于使用的震级计算公式和观测仪器不同，IGCEA测定的面波震级总体上要比NEIC测定的结果偏高0．2级；对于3．5～4．5级的地震，IGCEA测定的震级比NEIC测定的震级偏高0．3级；对于5．0～6．5级的地震，IGCEA偏高0．2级；对于7．0级以上的地震，IGCEA偏高小于0．1级．

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.