Attenuation characteristics of peak horizontal acceleration in Northeast and Southwest China

Regional seismic characteristics in northeastern and southwestern China are quite different. Earthquakes are more frequent in SW China than in NE China and intensity attenuates faster in SW China than in NE China. Through regression analyses of data from these two regions we have found the attenuation of peak horizontal accelerations also to be noticeably different. For northeastern China the regression is log₁₀(a) = ?0.474 + 0.613M ? 0.873 log₁₀ (R) ?0.00206R and for southwestern China, the regression is log₁₀ (a) = 0.437 + 0.454M ? 0.739 log₁₀ (R) ?0.00279R where a is acceleration in cm/sec², M is the Chinese surface wave magnitude (Institute of Geophysics, State Seismological Bureau), and R is the distance in kilometres. The formula for northeastern China has distance coefficients similar to those for Central United States as derived by Nuttli and Herrmann¹⁴.