Analisis dan Karakterisasi Atenuasi Gelombang Coda Daerah Jailolo

Wibowo, Zahra Quisha (2025) Analisis dan Karakterisasi Atenuasi Gelombang Coda Daerah Jailolo. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Jailolo, ibukota Halmahera Barat, terletak di kawasan dengan aktivitas seismik tinggi akibat kompleksitas tektonik regional. Wilayah ini dipengaruhi oleh sistem subduksi ganda, yaitu lempeng Pasifik yang bergerak menuju busur Halmahera di timur dan lempeng Eurasia menuju busur Sangihe di barat, serta aktivitas magmatik Gunung Jailolo. Kondisi geologis kompleks ini menghasilkan risiko seismik yang signifikan di daerah Jailolo. Untuk memahami karakteristik bawah permukaan dan mendukung mitigasi bencana, penting dilakukannya studi heterogenitas menggunakan analisis atenuasi gelombang gempa. Penelitian ini menerapkan metode atenuasi gelombang coda dengan memanfaatkan data gempa lokal yang direkam oleh 12 stasiun seismik di wilayah Jailolo. Parameter yang dianalisis meliputi quality factor coda pada frekuensi 1 Hz (Q₀) dan ketergantungan frekuensi (η) dalam interval waktu 20-120 detik. Analisis dilakukan pada rentang frekuensi 1, 1.5, 2, 3, 4, 6, 8, 10, 12, dan 14 Hz. Hasil penelitian menunjukkan nilai Q₀ yang relatif rendah sekitar 89, mengkonfirmasi tingkat seismisitas tinggi dan aktivitas tektonik yang intens di wilayah ini. Nilai η yang diperoleh tergolong tinggi dengan rata-rata η > 1, mengindikasikan heterogenitas bawah permukaan yang signifikan. Evaluasi nilai Q_c pada frekuensi 1.5 Hz, 3 Hz, 6 Hz, dan 12 Hz memperlihatkan variasi spasial atenuasi antar stasiun pengamatan. Stasiun SP05 dan SP13 menunjukkan atenuasi rendah, sementara stasiun SP15 dan SP27 menunjukkan atenuasi tinggi. Variasi ini mencerminkan struktur bawah permukaan yang tidak homogen di wilayah Jailolo. Temuan ini memberikan informasi penting tentang karakteristik seismik dan struktur bawah permukaan wilayah Jailolo yang dapat digunakan dalam penilaian risiko gempa dan perencanaan mitigasi bencana di kawasan tersebut.
============================================================================================================================================ Jailolo, the capital of West Halmahera, located in a region characterized by high seismic activity due to regional tectonic complexity. This area is influenced by a double subduction system, where the Pacific Plate moves toward the Halmahera arc in the east and the Eurasian Plate toward the Sangihe arc in the west, along with magmatic activity from Mount Jailolo. These complex geological conditions result in significant seismic risk in the Jailolo region. To understand subsurface characteristics and support disaster mitigation efforts, heterogeneity studies using wave attenuation analysis are essential. This research applied coda wave attenuation methods utilizing local earthquake data recorded by 12 seismic stations in the Jailolo region. The analyzed parameters included coda quality factor at 1 Hz frequency (Q₀) and frequency dependence (η) within a 20-120 second time window. Analysis was conducted across frequency ranges of 1, 1.5, 2, 3, 4, 6, 8, 10, 12, and 14 Hz. Results showed relatively low Q₀ values of approximately 89, confirming high seismicity levels and intense tectonic activity in this region. The obtained η values were categorized as high with an average η > 1, indicating significant subsurface heterogeneity. Evaluation of Qc values at frequencies of 1.5 Hz, 3 Hz, 6 Hz, and 12 Hz revealed spatial variations in attenuation between observation stations. Stations SP05 and SP13 showed low attenuation, while stations SP15 and SP27 exhibited high attenuation. These variations reflect the heterogeneous and non-uniform subsurface structure in the Jailolo region. These findings provide important information about seismic characteristics and subsurface structure of the Jailolo area that can be utilized for earthquake risk assessment and disaster mitigation planning in the region.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Coda Wave Attenuation, Heterogeneity, Jailolo, Quality Factor of Coda (Q_c).
Subjects:	Q Science > QE Geology > QE538.8 Earthquakes. Seismology
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	Zahra Quisha Wibowo
Date Deposited:	29 Jul 2025 08:46
Last Modified:	29 Jul 2025 08:46
URI:	http://repository.its.ac.id/id/eprint/122629

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