Comparison of Strong Ground Motion Recordings of the Lushan, China, Earthquake of 20 April 2013 with the Next Generation Attenuation (NGA)-West2 Ground-Motion Models

A total of 39 free-field accelerograms in the 2013 M-w 6.7 Lushan earthquake, with the closest site-to-rupture distances (R-rup) being less than 200 km, are compared with the median ground motions predicted by the recent Next Generation Attenuation (NGA)-West2 ground-motion prediction equations (GMPEs). Overall, for most Lushan station recordings over the whole range of Rrup, the spectral acceleration (SA) of the peak ground acceleration (PGA) and of T = 0: 06 s are within one standard deviation of the predictions from the five NGA-West2 GMPEs. Most intraevent residuals also fall between plus and minus one standard deviation from the predictions. Moreover, the standard deviation of intraevent residuals are smaller for SA of T = 0: 06 s than for PGA, which suggests that the application of NGA-West2 in predicting high-frequency ground motion due to the Lushan earthquake is acceptable. The spatial contours of intraevent residuals for PGA predicted by the five NGA-West2 models are almost the same, all showing four regions of negative intraevent residuals. Three of these regions are mainly distributed with the source-to-site azimuth approximating to 90 degrees or -90 degrees and the other one approximating to -180 degrees, which are consistent with the extrusion and rupture directions of the Lushan earthquake fault. In general, the five NGA-West2 GMPEs generate relatively large intraevent residuals at the long period (T = 1: 0 s) for R-rup exceeding 100 km, although the intraevent residuals are not as large. The short-period hanging-wall effects are more consistent with the NGA-West2 hanging-wall scaling than those of long period, and the short-period ground motions on the footwall are more consistent with the NGA-West2 models than those on the hanging wall.