Abstract:We select concentrations of earthquakes of varying times, spaces and magnitudes, and calculate station magnitude bias and network-average values, based on digital waveform data recorded by regional seismic networks and relevant seismic phase data as collected by the China Earthquake Networks Center. We perform quantitative statistical analysis of the magnitude deviation of each station after eliminating effects due to source, path and direction. Considering different tectonic structures in Sichuan Basin, the western Sichuan plateau and the Panzhihua-Xichang area, the problem of local magnitude bias is discussed from the point of view of regional seismic wave attenuation characteristics, in order to render the magnitude correction value of station more reasonable. In our study, for stations in Sichuan basin and the south section of Longmenshan fault, greater magnitudes are functions of low attenuation in structure and amplification of both basin effects and seismic stations;these require negative correction. For stations in the northern and middle sections of Longmenshan fault, their lower magnitudes require positive correction. For stations in western Sichuan plateau, the possible causes of the lower magnitudes are severe dependence upon source region due to low Q value, path effect attenuation, and small magnitude estimated by weak S-wave. For stations in the Panzhihua-Xichang area, magnitude deviation varies with the location of epicenter;the greater magnitudevaluesoccurwhen earthquakes occur in Sichuan basin appear to be well correlated with edge effect of sedimentary basin on strong ground motion; these require negative correction. Furthermore, the ray path passes through the Sichuan plateau and Panzhihua-Xichang area, so that the two high attenuation areas may be the main cause of low magnitude values for plateau earthquakes, thus requiring positive correction.