Strong-Motion Observations of the Lushan Earthquake on 20 April 2013

Abstract

Online Material: Additional figures of acceleration time series; table of station parameters, associated ground motion intensities. On 20 April 2013, at 08:02 a.m. Beijing time, a strong earthquake hit Lushan, a county in the southwest of Sichuan Province in China. During this earthquake, a total of 114 strong‐motion stations from the new generation of the National Strong‐Motion Observation Network System (NSMONS) of China were triggered. The NSMONS consists of 1154 permanent free‐field stations and began to operate in March 2008. The 2008 Wenchuan destructive earthquake triggered a large number of strong‐motion recordings that contribute significantly to the world strong‐motion database (Li, Zhou, Huang, et al. , 2008). The 2013 Lushan earthquake also provided a large number of near‐source recordings in China (Xie et al. , 2014). NSMONS aims to enhance the ability of earthquake monitoring and the collection of strong‐motion recordings in the most seismically active regions and some major cities in the Chinese mainland. As a result, its free‐field stations are irregularly distributed with an average spacing of 50 km to hundreds of kilometers (Li, Zhou, Yu, et al. , 2008). Thus, it definitely cannot monitor all of the seismic areas in China. For example, on 14 April 2010, the Yushu earthquake, which exhibited a magnitude of M s 7.1, occurred in the northeast part of the Tibetan plateau at Yushu, Qinghai Province. Only five strong‐motion stations of NSMONS were triggered, the nearest of which was approximately 350 km from the epicenter, and the maximum peak ground acceleration (PGA) was only approximately 2 cm/s2. Taking into account the randomness of the spatial distribution of earthquakes, most strong‐motion recordings obtained in recent years have small amplitudes and are thus not of interest to engineers (China Strong Motion Networks Center, 2012). As a result, these recordings only contribute to the steady growth of the strong‐motion …