ESTIMATION VS VALUE’S BASED ON MICROTREMOR DATA BENEATH MT. TANGKUBAN PARAHU AREA, WEST JAVA

• Main Author: Fachrani, Zuhaa
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/82519
• Institution: Institut Teknologi Bandung

Mt. Tangkuban Parahu is an active stratovolcano located in West Java, known has preatic eruption. Since early 19th century, Mt. Tangkuban Parahu have 22 volcanic activity i.e formation of new fumarole, increased seismicity, and multiple eruptions. The volcanic activity in 2013 and 2019 is believed to have influenced the accumulation of sediment in the area surrounding Mt. Tangkuban Parahu. This study utilized the HVSR method with three component microtremor data to analyze the natural frequency distribution of subsurface geological structures around the volcano. This research aims to enhance the understanding of the relationship between shallow geological structures and microtremors around volcanic environments by mapping the thickness of volcanic deposits using S-wave velocity profiles. The research used microtremor data from 30 seismic stations, including 5 broadband and 25 temporary seismic stations. The microtremor data had a recording duration of ±24 hours spanning late 2021 to early 2022. Using the HVSR method, important parameters such as natural frequency (f0) and amplification (A0) were determined. The inversion process provided insights into the Vs profile beneath Mt. Tangkuban Parahu. The results revealed that station TPB1 recorded the lowest f0 value at 1.15673 Hz, while station TPA4 registered the highest f0 at 10.9398 Hz. Form the inversion result, seen the value of Vs30 is varies, namely 171,716 m/s – 332,749 m/s, with dominance of rock classes D that descript to be medium soil and one station has rock class E which classified as soft soil.