ANALYSIS OF MICROTREMOR DATA FOR ESTIMATION OF SHEAR WAVE VELOCITY AND THE SITE AMPLIFICATION POTENCY BY SURFACE SEDIMENT LAYER IN SOLOK CITY, WEST SUMATRA

• Main Author: Novelyarisyanti, Nova
• Format: Theses
• Language: Indonesia
• Subjects: Ilmu kebumian
• Online Access: https://digilib.itb.ac.id/gdl/view/74687
• Institution: Institut Teknologi Bandung

The city of Solok is located along the active Sumatran fault line which is better known as the Sianok Segment and the Sumani Segment. The two segment is very interesting because of the history of damage caused by the earthquake and its location in a densely populated area. In addition, the Solok City area is covered by alluvium deposit and weathered soil. Therefore, Solok City is vulnerable to damage caused by shocks from seismic waves originating from the earthquakes. The shaking can experience amplification caused by the surface sediment layer. Therefore, it is necessary to have a better understanding soil dynamic characteristics in this region. One of the parameters that play an important role in estimating wave amplification is the shear wave velocity. In this study the shear wave velocity was obtained from modeling array microtremor data while the amplification value was obtained from a combination of array and single station data. Array microtremor measurements were carried out at 9 locations while single station microtremor measurements were carried out at 98 locations. Based on the results of the microtremor array modeling at 9 locations, the Vs value in the surface sediment layer ranges from 113.33 m/s to 210.02 m/s which describes alluvium deposits. The dominant frequency of the sediment layer in the study area ranges from 0.35 Hz to 14.75 Hz. The amplification value calculation results range from 1.04 to 1.94 and the seismic vulnerability index values in the study area range from 0.07 to 5.81. Areas with a high vulnerability index are in the south part which generally occupy areas of floodplain deposits and alluvium deposits, these areas also have amplifications that tend to be greater than other areas.