Site characterization study with microtremor data: A case study at the West Borneo NPP potential site

A site characterization using a microtremor measurement study was conducted at the West Borneo nuclear power plant (NPP) potential site as a preliminary feasibility study. This study measured the natural resonant frequency of soil and estimated the subsurface V-S as prior information for the design planning of an NPP building foundation. The single station microtremor data were processed using the horizontal-to-vertical spectral ratio (HVSR) method to obtain the f(0) and A(0) values, and the array data were processed using the spatial autocorrelation (SPAC) method. The study area was classified based on the f(0) and A(0) values. Due to the unavailability of borehole data and limited array data, the HVSR curve was used to estimate the V-S profile. The HVSR curve V-S estimation was calculated using Rayleigh wave ellipticity inversion. The inversion results were constrained by V-S profiles from SPAC and regional geology data to ensure that the inverted model was rational. It was demonstrated that the constrained inversion process could generate a rational subsurface model for Pantai Gosong's coastline. Based on the result, the feasible bedrock for the NPP building foundation was found at a depth of 40 m in the coastline area.