Penerapan Metode Mikrotremor Untuk Studi Site Effect Dan Directional Amplification Di Zona Sesar Somorkoneng, Bangkalan

Prapaska, Mikael Mario Putra (2023) Penerapan Metode Mikrotremor Untuk Studi Site Effect Dan Directional Amplification Di Zona Sesar Somorkoneng, Bangkalan. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Melalui penelitian ini, telah diselidiki getaran mikrotremor yang dihasilkan oleh sekitar, yang direkam pada sejumlah titik akuisisi yang didesain terletak di sepanjang sesar dan memotong sesar Somorkoneng, Bangkalan. Pengukuran dilakukan dengan metode mikrotremor single station yang direkam menggunakan seismometer portabel tipe SARA SL-07 pada 42 titik ukur. Data mikrotremor diproses menggunakan metode Horizontal to Vertical Spectral Ratio (HVSR) dan metode H/V Rotate. Metode HVSR menghitung rasio spektrum horizontal terhadap spektrum vertikal dari data mikrotremor. Metode H/V Rotate menerapkan prinsip serupa HVSR namun dengan memutar komponen horizontal dari 0º hingga 180º sehingga dapat diketahui perbedaan rasio H/V untuk setiap azimuthnya. Penelitian ini bertujuan untuk melakukan karakterisasi site effect ditinjau dari nilai frekuensi dominan dan amplitudo dari hasil analisis Horizontal to Vertical Spectral Ratio (HVSR). Selain itu penelitian ini juga mempelajari Directional Amplification pada zona Sesar Somorkoneng dengan metode H/V Rotate untuk identifikasi jalur sesar. Hasil yang diperoleh menunjukkan nilai frekuensi dominan bervariasi antara 2 – 19 Hz, namun berdasarkan interpretasi, wilayah penelitian didominasi oleh frekuensi yang tinggi (>6.67Hz). Distribusi nilai faktor amplitudo, tergolong dalam rentang amplitudo rendah hingga tinggi dengan nilai yang berkisar diantara 2 – 8 namun di dominasi oleh rentang amplitudo sedang, berkisar antara 2 hingga 5. Hasil tersebut berkorelasi dengan kondisi geologi wilayah penelitian. Berdasarkan analisis H/V Rotate, diketahui bahwa directional amplification menunjukkan arah dominan Utara – Selatan sepanjang duapertiga awal sesar pada wilayah penelitian dimulai dari sisi Barat, sedangkan pada sepertiga sesar di sisi Timur menunjukkan menunjukkan pola directional amplification yang acak. Sehingga, dapat di interpretasikan bahwa arah dominan Utara – Selatan dapat memberikan validasi terhadap keberadaan sesar, sedangkan pada sepertiga akhir jalur sesar yang digambarkan, tidak dapat terlihat jelas berdasarkan analisis directional amplification.
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Through this study, microtremor vibrations produced by nature have been investigated. Data recorded at a number of acquisition points designed to be located along and intersect the Somorkoneng fault, Bangkalan. Measurements were carried out using a portable seismometer type SARA SL-07 at 42 measuring points. Microtremor data is processed using the Horizontal to Vertical Spectral Ratio (HVSR) method and the H/V Rotate method which applies the same principle as HVSR but by rotating the horizontal component from 0º to 180º to determine the difference in H/V ratio for each azimuth. The aim of this study was to characterize site effects in terms of dominant frequency and amplitude values from the analysis of Horizontal to Vertical Spectral Ratio (HVSR). In addition, this study also investigated Directional Amplification in the Somorkoneng Fault zone using the H/V Rotate method to identify the fault path. The results showed that the dominant frequency values varied between 2-19 Hz, but dominated by high frequencies (>6.67Hz). The distribution of amplitude factor values was classified into a range of low to high amplitudes with values ranging from 2-8 but dominated by the range of moderate amplitudes, ranging from 2 to 5. These results correlated with the geological conditions of the study area. Based on the H/V Rotate analysis, it was found that directional amplification showed a dominant North-South direction along two-thirds of the fault in the study area starting from the West side, while in the one-third of the fault on the East side, shows a random directional amplification pattern. Thus, it can be interpreted that the dominant North-South direction can provide validation for the existence of faults, while on the contrary, the fault line cannot be clearly seen through the directional amplification analysis.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Mikrotremor, HVSR, Sesar, Directional Amplification; Microtremor, HVSR, Fault, Directional Amplification
Subjects:	Q Science > QE Geology > QE538.8 Earthquakes. Seismology T Technology > T Technology (General) > T174.5 Technology--Risk assessment. T Technology > T Technology (General) > T57.5 Data Processing
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	Mikael Mario Putra Prapaska
Date Deposited:	30 Aug 2023 00:51
Last Modified:	30 Aug 2023 00:51
URI:	http://repository.its.ac.id/id/eprint/103304

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