Estimation of Ground Shear Strain using Horizontal to Vertical Spectral Ratio (HVSR) in Bandung Region, West Java, Indonesia Faisal Mamonto (a*), Zulfakriza (b,c), Andri Dian Nugraha (b,c)
a) Master Program of Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, Indonesia
*mamonto.faisal[at]gmail.com
b) Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, Indonesia
c) Center for Earthquake Science and Technology, Institut Teknologi Bandung, Bandung, Indonesia
Abstract
Bandung region, West Java, Indonesia is a basin area that consist of soft sedimentary profiles and lies on active tectonic zone. This condition probably has the potential for strengthening ground shaking due to vibrations caused by earthquake events in Bandung region. We applied the Horizontal to Vertical Spectral Ratio (HVSR) microtremor method to determine the dynamic response of ground shear strain. We used 51 temporary seismic station in research collaboration between ITB and Australian National University in 2014. This study used 2 hours length of waveform at night recording (20.00 to 23.00 local time) to obtain the HVSR curve. It allows us to estimate the dominant frequency and maximum amplification factor. Then, we estimate dominant period values, earthquake vulnerability index and peak ground acceleration (PGA) based on dominant frequency and the maximum amplification factor and calculate the ground shear strain (GSS). We found the range of number of GSS are \(1\times10^{-5}\) to \(13,3\times10^{-3}\). We interpret that the high number of GSS \(13,3\times10^{-3}\) correspond to weak zone of soil characteristic and possible to be cracks or subsidence. The areas that show high value of GSS are Solokan Jeruk, Ciparay and Majalaya.
