TitleNS24A-03 - Site Response study from Strong Ground Motion data over Chubu region, Japan
Session Start2022-12-13 13:45:00 CST
Session End2022-12-13 14:45:00 CST
AuthorSupriya
AbstractSite response study is a technique that is helpful for evaluating soil sediments of the surficial crust on strong ground motion. The Kanto earthquake that happened in 1923 showed us that surficial geology plays a major role in controlling damages caused by destructive earthquakes. But it took decades long to accept the fact over the wide earthquake engineering community. In this study, site characterization has been done by using Nakamura�s Horizontal to Vertical Spectral Ratio Technique (HVSR). A small 1��1� region is chosen over the Kanazawa which belongs to Chubu region, Japan. Ten years of strong ground motion data is obtained from KiK NET maintained by NIED (National Research Institute for Earth Science and Disaster Resilience). Waveforms of duration 120 seconds are chosen following the onset of P arrivals. A ten seconds window is marked following the onset of S-waves. Fast fourier Transformation (FFT) of the ten second window converted the time series waveforms in the frequency domain. The Horizontal to Vertical Spectral Ratio (HVSR) is obtained by averaging each Horizontal and Vertical component recorded by the stations present over the region. Out of 18 stations present over the region, each event has been recorded by a minimum of 6 stations. Plotting of H/V spectral ratio with a frequency range from 1 to 10 Hz gives us the Predominant frequency (fpeak) over the regions which was found between 2.1 and 9.92 Hz. The predominant frequency values show peaks at a lower frequency at sites corresponding to class C to D whereas shows fpeak values at higher frequencies for class C to B which shows that with an increase in compaction of sediments fpeak increases here the sediment ranges from stiff soil to soft rock. The VS30 values are needed to correlate the surficial lithology. Site characterization study using this method will help to control loss and damages caused by destructive earthquakes.