Spatial autocorrelation (SPAC) method with L-shaped array in South Tangerang, Indonesia

Several methods of processing microtremor data have been developed, including Spatial Autocorrelation or Spatially Averaged Coherency Spectra (SPAC) Method. Various types of array shapes in this method such as linear-shaped, L-shaped, triangle-shaped, and circular-shaped array. Among them, the triangle array is the most common. Due to some limitations on the field during the survey, sometimes the triangle array is more difficult to deploy where only L shape array can be done. The purpose of this study is aimed to evaluate the L-shaped array in estimating shear wave velocity structure. Data acquisition was conducted next to the micro-seismic monitoring station of the Experimental Power Reactor (RDE) Site, South Tangerang, Indonesia. An L-shaped array with a combination of different array sizes and the azimuth angle is performed. The phase velocity dispersion curves and shear wave velocity curves of L-shaped arrays with the same array size and different azimuth coincide quite well with those of L-shaped arrays with the same different azimuth and array size. It observed that the different combinations in terms of array size and azimuth produce similar shear wave velocity profiles. Based on the results of the analysis, an L-shaped array can be utilized in order to estimate the shear wave velocity structure.