Assessment of Local Site Condition on Seismic Ground Motion in Arak, Using Experimental Measurements and Numerical Modeling

摘要

In order to estimate the seismic site response of alluvial deposits in Arak, spectral analysis of microtremor data in 20 locations (in northwest-southeast and northeast-southwest sections) has been performed. Using horizontal-to-vertical spectral ratio (H/V) on the recorded data, natural periods and corresponding amplification factors of soil layers, and using Rayleigh wave inversion techniques, the thickness of the soil layers and depth of seismic bedrock were estimated. In addition, 1D numerical analyses using DEEPSOIL software and 2D modeling using PLAXIS program, linearly at low strain levels, were performed and the results were compared to experimental technique. The comparison of microtremor results with 1D and 2D numerical modeling results shows a 25% difference in NW-SE direction. This difference can be attributed to the magnitude of seismic waves in a one-dimensional and two-dimensional analysis of this study. While in the northeast-southwest directions, the results are fairly consistent indicating one-dimensional site behavior in this direction.