3期 俞言祥等:中国东部和西部地区水平向基岩加速度反应谱衰减关系 217 Attenuation Relations for Horizontal Peak Ground Acceleration and Response Spectrum in Eastern and Western China Yu Yanxiang and Wang Suyun (Institute of Geophysics, China Earthquake Administration, Beijing 100081, China) Abstract By taking the western part of North America as the reference region, the attenuation relations for horizo