Microtremor-based analysis of the dynamic response characteristics of earth-fissured sites in the Datong basin, China

This study conducted microtremor testing along six survey lines that cross three typical earth fissures in the Datong basin to determine the dynamic response characteristics of earth fissure sites with regard to the Fourier amplitude spectrum, response spectrum, and Arias intensity. The results show the following. (1) The predominant frequency of an earth fissure site is mainly affected by the thickness and the shear wave velocity of the soil layer and is minimally effected by the presence of an earth fissure. (2) Earth fissures have a pronounced amplification effect on dynamic response. Fourier amplitude, response acceleration, and Arias intensity are high near an earth fissure and decrease with an increase in distance from the earth fissure, tending toward stability at a distance of 20 m. (3) The area that is seriously affected by this amplification is within 6–8 m of an earth fissure, and the general affected area is farther out than this, to a distance of 25 m. (4) New construction should be avoided in an area affected by the amplification, and existing buildings in general and seriously affected areas need to be reinforced to increase their seismic fortification intensity.