Relokasi Hiposenter Gempa Bumi Menggunakan Metode Double Difference Di Wilayah Cianjur

Putri, Dhiva Hikari (2025) Relokasi Hiposenter Gempa Bumi Menggunakan Metode Double Difference Di Wilayah Cianjur. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Indonesia merupakan wilayah dengan aktivitas seismik tinggi akibat pertemuan tiga lempeng utama, yaitu Eurasia, Indo-Australia, dan Pasifik. Salah satu daerah yang rawan gempa adalah Cianjur, Jawa Barat, yang dipengaruhi oleh sesar aktif dan zona subduksi di selatan Jawa. Penelitian ini bertujuan untuk merelokasi hiposenter gempa bumi di wilayah Cianjur, Jawa Barat, menggunakan metode Double-Difference dengan data katalog BMKG tahun 2019–2023. Dan menentukan perbedaan nilai residual waktu tempuh gempa sebelum dan sesudah relokasi. Proses dilakukan melalui dua tahapan: ph2dt untuk membentuk jaringan antar kejadian gempa dengan jarak minimum, dan hypoDD untuk menghitung diferensiasi waktu tempuh gelombang antar kejadian. Sebanyak 143 gempa berhasil direlokasi dengan nilai CND berkisar antara 45–67, menunjukkan hasil yang akurat dan stabil. Nilai residual waktu tempuh sebelum relokasi tersebar luas (±2000 ms) dan tidak terpusat, sedangkan setelah relokasi, distribusinya menjadi lebih ramping dan simetris di sekitar nol dengan konsentrasi utama dalam rentang ±500 ms. Hal ini menunjukkan peningkatan kecocokan antara waktu tiba observasi dan model, serta keberhasilan relokasi dalam meningkatkan akurasi posisi hiposenter. Histogram residual membuktikan bahwa metode Double-Difference secara signifikan mengurangi selisih waktu tiba antar fase, serta meningkatkan kesesuaian spasial data gempa. Seluruh event pada data awal berhasil direlokasi kembali secara utuh (100%), yang memperkuat validitas proses. Dengan demikian, relokasi ini efektif dalam memperbaiki presisi spasial distribusi hiposenter dan dapat digunakan sebagai dasar untuk analisis struktur geologi serta upaya mitigasi bencana gempa bumi di wilayah Cianjur.
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Indonesia is a region with high seismic activity due to the convergence of three major tectonic plates: the Eurasian, Indo-Australian, and Pacific plates. One of the earthquake-prone areas is Cianjur, West Java, which is influenced by active faults and a subduction zone south of Java. This study aims to relocate earthquake hypocenters in the region using the Double-Difference method based on BMKG earthquake catalog data from 2019 to 2023, and to evaluate changes in travel-time residuals before and after relocation. The process involves two stages: ph2dt, which builds a network of closely spaced earthquake pairs, and hypoDD, which calculates differential travel times between those pairs. A total of 143 earthquake events were successfully relocated, yielding CND values ranging from 45 to 67, indicating high accuracy. Prior to relocation, travel-time residuals were widely distributed (±2000 ms) and poorly centered; after relocation, the distribution became more focused and symmetric around zero, with most values within ±500 ms. This improvement indicates better agreement between the velocity model and observational data, demonstrating the method's effectiveness in enhancing spatial accuracy of hypocenter locations. The residual histogram confirms the success of the relocation, with 100% of the initial events successfully relocated. These results provide a reliable basis for geological structure analysis and earthquake disaster mitigation planning in the Cianjur region.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Hiposenter, Gempa Bumi, Metode Double Difference, Residual Waktu Tempuh, Hypocenter Relocation, Earthquake, Double Difference Method, Travel Time Residuals.
Subjects:	Q Science Q Science > Q Science (General) Q Science > QC Physics Q Science > QE Geology Q Science > QE Geology > QE538.5 Seismic tomography; Seismic waves. Elastic waves Q Science > QE Geology > QE538.8 Earthquakes. Seismology
Divisions:	Faculty of Science and Data Analytics (SCIENTICS) > Physics > 45201-(S1) Undergraduate Thesis
Depositing User:	Dhiva Hikari Putri
Date Deposited:	26 Jul 2025 12:59
Last Modified:	26 Jul 2025 12:59
URI:	http://repository.its.ac.id/id/eprint/121539

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