Haryono, Arif (2022) Identifikasi Sesar Grindulu Dan Daerah Rawan Bencana Di Kabupaten Pacitan Berdasarkan Data Self-Potential (SP), Very Low Frequency-Electromagnetic (VLF-EM), Dan Mikrotremor. Doctoral thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Sesar Grindulu merupakan salah satu sesar aktif yang terletak di Kabupaten Pacitan. Sesar ini memanjang sekitar 33 km, membelah daerah Pacitan dengan arah timur laut – barat daya (NE–SW), dan melewati lima kecamatan yang merupakan daerah padat penduduk. Untuk mengurangi dampak kerusakan akibat gempabumi yang mungkin terjadi di Pacitan, perlu adanya mitigasi gempabumi dengan cara mengidentifikasi Sesar Grindulu yang diduga sebagai sumber gempabumi di Pacitan dan memetakan daerah-daerah yang rawan terdampak bencana. Dalam penelitian ini, identifikasi sesar dan daerah rawan bencana dilakukan dengan menggunakan tiga metode geofisika, yaitu: Self-Potential (SP), VLF-EM, dan Mikrotremor. Proses pengolahan data menggunakan pemodelan inversi dengan metode CSA (Crow Search Algorithm) untuk data SP, filter Fraser dan Karous-Hjelt untuk data VLF-EM, dan metode HVSR (Horizontal to Vertical Spectral Ratio) untuk data mikrotremor. Berdasarkan hasil pemodelan inversi menggunakan metode CSA pada data SP berhasil diidentifikasi Sesar Grindulu di Desa Tambakrejo dengan kedalaman 11,06 hingga 102,74 m dan dip sebesar 75,58o. Sesar Grindulu juga berhasil diidentifikasi di Kecamatan Arjosari pada kedalaman semu antara 10 hingga 50 m yang secara umum mempunyai orientasi arah timur laut – barat daya (NE–SW) menggunakan metode filter Fraser dan Karous-Hjelt berdasarkan data VLF-EM. Sedangkan pengolahan data mikrotremor menggunakan metode HVSR berhasil mengidentifikasi daerah-daerah yang rawan terdampak bencana gempabumi akibat aktivitas Sesar Grindulu adalah Kecamatan Pacitan, Tegalombo, dan Nawangan ditunjukkan dengan nilai indeks kerentanan seismik (Kg) yang tinggi. Ditinjau dari pola tegasannya, Sesar Grindulu termasuk sesar geser dengan rezim tegasan bertipe strike-slip. Sedangkan menurut konsep Moody dan Hill, Sesar Grindulu digolongkan ke dalam sesar geser orde pertama.
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Grindulu Fault is one of the active faults located in Pacitan Regency. This fault extends for about 33 km, divides the Pacitan area in a Northeast-Southwest direction, and passes through five sub-districts which are densely populated areas. To reduce the impact of damage caused by earthquakes that may occur in Pacitan, it is necessary to have earthquake mitigation by identifying the Grindulu Fault which is suspected to be the source of the earthquake in Pacitan and mapping areas that prone to disasters. In this study, the identification of fault and disaster-prone areas were carried out using three geophysical methods, namely: Self-Potential (SP), VLF-EM, and Microtremor. The data processing uses inverse modeling with the CSA (Crow Search Algorithm) method, Fraser and Karous-Hjelt filters, and the HVSR (Horizontal to Vertical Spectral Ratio) method. for SP data, VLF-EM data, and microtremor data, respectively. Based on the results of inverse modeling using the CSA method on SP data, it was identified the Grindulu Fault in Tambakrejo Village with a depth of 11.06 to 102.74 m and a dip of 75.58o. The Grindulu Fault was also identified in Arjosari Subdistrict at an apparent depth of 10 to 50 m with an orientation in a northeast–southwest (NE–SW) direction using the Fraser and Karous-Hjelt filter methods based on VLF-EM data. Meanwhile, microtremor data processing using the HVSR method succeeded in identifying areas prone to earthquakes due to the Grindulu Fault activity, namely Pacitan, Tegalombo, and Nawangan Subdistricts indicated by a high value of the seismic vulnerability index (Kg). Based on the stress pattern, the Grindulu Fault is a strike-slip fault with type of stress regime is strike-slip. Meanwhile, according to the Moody and Hill concept, the Grindulu Fault is classified as a first-order strike-slip fault.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Uncontrolled Keywords: | Sesar Grindulu, Pacitan, Self-Potential (SP), VLF-EM, Mikrotremor, Grindulu Fault, Pacitan, Self-Potential (SP), VLF-EM, Microtremor |
| Subjects: | Q Science Q Science > QC Physics |
| Divisions: | Faculty of Science and Data Analytics (SCIENTICS) > Physics > 45001-(S3) PhD Thesis |
| Depositing User: | Mr. Marsudiyana - |
| Date Deposited: | 09 Oct 2025 06:55 |
| Last Modified: | 09 Oct 2025 06:55 |
| URI: | http://repository.its.ac.id/id/eprint/128543 |
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