Evaluation of ground dynamic characteristics using ambient noise measurements in a landslide area

Abstract

One of the most important steps for the evaluation of landslide is the investigation of ground dynamic characteristics. The determination of ground dynamic characteristics significantly helps to evaluate site effects and identify critical areas on the slope. One of the most important ground dynamic characteristics is the shear wave velocity. It is possible to detect the seismic impedance, slip surface, and depth to the bedrock using shear wave velocity profiles. There are various methods for calculating the shear wave velocity, among which single-station ambient noise measurement is one of the least costly and fastest. Hence, single-station ambient noise measurements are taken at 30 points in order to determine ground dynamic characteristics and estimate the shear wave velocity in Nargeschal landslide area. At first, ambient noises are analyzed using the H/V method and the fundamental frequency is calculated. Then, Rayleigh wave ellipticity is determined by RayDec method in order to estimate the 1D shear wave velocity profiles. A 3D shear wave velocity model is developed by interpolation between 1D shear wave velocity profiles in the study area. The slip surface, depth to the bedrock, and, generally, subsurface conditions and ground dynamic characteristics are estimated in the landslide area using the 3D shear wave velocity model. Investigations show good agreement between the results of ambient noise measurements and geotechnical, geological, and geophysical data in the study area.