VULNERABILITY ANALYSIS OF EARTHQUAKE HAZARDS IN TASIKMALAYA CITY USING HORIZONTAL TO VERTICAL SPECTRAL RATIO (HVSR) METHOD
Tasikmalaya City is one of the regions in West Java Province that is often hit by earthquakes. This is due to its location that close to the Indo-Australian Plate subduction zone towards the Eurasian Plate. The surface deposits in this city are alluvium and weakly consolidated step deposits which...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/53160 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Tasikmalaya City is one of the regions in West Java Province that is often hit by
earthquakes. This is due to its location that close to the Indo-Australian Plate
subduction zone towards the Eurasian Plate. The surface deposits in this city are
alluvium and weakly consolidated step deposits which can cause wave
amplification during an earthquake, so that the vibrations that are felt will be
stronger. As an effort to mitigate the earthquake disaster in the City of Tasikmalaya,
seismic zoning needs to be carried out to map the areas that will experience heavy
damage when an earthquake occurs. This study uses the Horizontal to Vertical
Spectral Ratio (HVSR) method which is applied to the microtremor recording data
to obtain spatial variations in the predominant frequency and amplification values
that can explain the characteristics of the geological layer beneath the surface.
Based on the obtained results, the predominant frequency ranging from 0.71 to 9.42
Hz with the lowest frequency distribution in the eastern, southeastern, and
northwestern parts, which indicates a sediment layer that tends to be thicker. The
range of amplification values are from 1.15 to 12.59 with the distribution of higher
values in the eastern, southeastern, southern, and northwestern parts of the
research area. The inversion of the HVSR curves was carried out to determine the
value of shear wave velocity (????!) in order to obtain a more detailed subsurface
geological structure that can be used to determine the level of vulnerability of
earthquake hazards. The Neighborhood Algorithm is used to find an optimum
model. Based on the results of the inversion process, the ????! ranging from 150 to
3054 m/s with lower ????
! values in the eastern, southeastern, and northwestern parts
at depth of about 25 meters. The average value of shear wave velocity at a depth of
30 meters (????!"#) can also be used to determine the type of soil for geotechnical
study. From the obtained ????!"#data, the types of soil in the research area are
classified into moderate soil, hard soil, and rocks. |
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