Seismic Ground Motion Amplification in a 3D Sedimentary Basin: Source Mechanism and Intensity Measures

Abstract

Ground motion amplification has been observed in most earthquakes triggered near the sediment-filled basins such as 2015 Nepal and 1999 Chi–Chi events. Many numerical studies pointed out the effect of various parameters such as material properties and geometric features of the basin on ground motion amplification but the effect of the complete range of source mechanism parameters needs to be addressed. This paper presents the effect of source mechanism parameters, such as strike, dip, rake angle of fault and moment magnitude ([Formula: see text] on amplification of ground motion intensity measures (IMs) due to sediment-filled basins. It is found out that the maximum spectral amplification, when subjected to the source of lateral strike mechanism, is 45, whereas for thrust fault mechanism, it is 30. Within the lateral strike mechanism, if the dip angle is increased from 0∘to 90∘, the spectral amplification increases from 10 to 30 times. The results also suggested that it is important to consider detailed focal parameters to study basin amplification. The amplification of IMs in the basin is more sensitive to variation of dip angle than the other source parameters and the magnitude of earthquake has an insignificant role in basin amplification.