Characteristics of Ground Acceleration and Features of Landslides Triggered by the Lushan Earthquake (China)

Abstract

The 2013 Lushan earthquake (Ms = 7.0; epicentre located at 30.3°N, 103.0°E), with a focal depth of 13.0 km was triggered by the reactivation of the Longmenshan fault in Lushan County, Sichuan Province, China on 20 April 2013. Although Lushan Ms 7.0 earthquake occurred on the same Longmenshan thrust belt as Wenchuan Ms 8.0 earthquake, they have very different characteristics of ground acceleration and features of landslides. Based on acceleration waveform data provided by national strong motion network center, a preliminary study was made on the main shock acceleration characteristics, especially vertical and horizontal acceleration ratio Va/Ha with epicentral distance, which indicated that Va/Ha ratio ranged only from 0.4 to 0.7, significantly less than the near-field earthquakes with the same magnitude. Meanwhile, it also showed that the vertical seismic force was less than the horizontal seismic force. FLAC 6.0 FDM software was used to analyse the progressive damage difference of numerical models of Donghekou rock landslide affected by the Lushan and Wenchuan earthquakes, respectively. Finally, acceleration data of ground motion observation in Lengzhuguan slope suffering from seismic waves of Lushan earthquake indicated that there was symmetrical relationship between predominant frequency and acceleration amplification curves.