Attenuation of peak ground accelerations from the great Wenchuan earthquake

                                                         Wang Dong¹ and Xie Lili^1,2

1. Institute of Engineering Mechanics, China Earthquake Administration, Harbin 150080, China

2. School of Civil Engineering and Architecture, Harbin Institute of Technology, Harbin 150090, China

Abstract: Over 800 accelerograms recorded by 272 ground-level stations during the Wenchuan earthquake are used to
analyze the influence of rupture distance, local site conditions and azimuth on peak ground accelerations (PGAs). To achieve
a better understanding of the characteristics of ground motions, the spatial distributions of the EW, NS and UD components
of PGAs are obtained. Comparisons between the EW and NS components, the fault-normal and fault-parallel components,
and the vertical and horizontal components of PGAs are performed, and the regression formula of the vertical-to-horizontal
ratio of PGAs is developed. The attenuation relationship of peak horizontal accelerations (PHAs) is compared with several
contemporary attenuation relationships. In addition, an analysis of residuals is conducted to identify the potential effects of
rupture distance, azimuth and site conditions on the observed values of PHAs. The analysis focuses on medium-hard soil site
conditions, as they provided most of the data used in this study.

Keywords: Wenchuan earthquake; peak ground acceleration (PGA); attenuation; rupture distance; azimuth



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