R.H. Hidayatullah, Supriyadi, Khumaedi, Sugiyanto
A research using microseismic instrument with Horizontal to Vertical Spectral Ratio (HVSR) method has been carried out in Kota Lama Semarang It is aimed at figuring out values of dominant frequency, ground vulnerability, ground shear strain (GSS), and the underground structure of research area. Thirteen observation points were included in this research, with each point being 100 m apart. The main variable of this research is microseismic signal. Microseismic signals obtained were analyzed using the HVSR method in order to get data of dominant frequency and ground amplification, which were then presented, in an H/V curve. This resulting curve was then used to calculate ground vulnerability, ground shear strain (GSS), and wave velocity (Vs), and was then utilized to analyze the subsurface structure of the research area. Results show that the dominant frequencies range from 0.76-0.96 Hz, maximum ground acceleration ranges from 5.55-6.35 gal, with ground shear strain in the range of 0.002-0.0076, and earthquake vulnerability around 0.5-9.5. That range of dominant frequencies indicates that the ground in the research area belongs to the medium category, in which it consists of alluvial rocks comprising of sand, pebble, clay, silt, and mud. These rocks have relatively low density and low dominant frequencies, while their ground amplifications are relatively medium with relatively deep layer thickness. This means that this area is prone to seismic tremor that comes with damage risks. © 2021 IEEE.
Universitas Negeri Semarang, Physics Department, Semarang, Indonesia
