Penentuan Model 1D Velocity Berdasarkan Relokasi Hiposenter di Laut Maluku, Indonesia

Nurridhiani, Fathan Ayu (2025) Penentuan Model 1D Velocity Berdasarkan Relokasi Hiposenter di Laut Maluku, Indonesia. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Wilayah timur Indonesia memiliki tatanan tektonik yang kompleks akibat interaksi tiga lempeng utama, yaitu Lempeng Eurasia, Indo-Australia, dan Pasifik, serta kehadiran Zona Tumbukan Laut Maluku (Molucca Sea Collision Zone/MSCZ). MSCZ memiliki karakteristik unik berupa subduksi ganda yang melibatkan busur gunungapi Halmahera di timur dan Sangihe di barat, serta menunjam hingga ke bawah Lempeng Filipina. Kompleksitas tektonik ini menghasilkan tingkat seismisitas yang tinggi di Laut Maluku hingga Halmahera, namun pemahaman mengenai mekanisme subduksi di wilayah ini masih terbatas. Hal ini disebabkan oleh keterbatasan stasiun seismik yang mengakibatkan kurangnya data gempa berskala kecil (M < 5) dan penggunaan model kecepatan global yang kurang representatif. Penelitian ini bertujuan untuk memperbarui katalog gempa di area MSCZ serta menghasilkan model 1D velocity lokal yang dapat membantu pemahaman struktur bawah permukaan secara lebih dalam. Dengan memanfaatkan data pada periode Juli 2016 hingga Agustus 2017 berjumlah 714 events, dengan total stasiun sebanyak 35. Penentuan lokasi awal berhasil dilakukan menggunakan inversi non-linear, yang menghasilkan 366 events. Estimasi ketidakpastian lokasi arah x, y, dan z adalah sebesar 8,45 km, 9,83 km, dan 0,05 km.. Ditentukan sebuah model 1D velocity minimum dari gelombang P dari 192 events, dengan kedalaman 0-50 km dengan nilai rentang kecepatan 4,58 km/s hingga 8,42 km/s. Kemudian, model kecepatan tersebut digunakan untuk relokasi menggunakan algoritma double-difference yang menghasilkan sebanyak 366 events dengan ketidakpastian di arah x, y, dan z secara berturut-turut 6,47 km, 8,27 km, dan 5,85 km.
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Eastern Indonesia is characterized by a complex tectonic framework resulting from the interaction of three major tectonic plates: the Eurasian, Indo-Australian, and Pacific plates, along with the presence of the Molucca Sea Collision Zone (MSCZ). The MSCZ exhibits a unique tectonic configuration, featuring double subduction involving the Halmahera volcanic arc to the east and the Sangihe arc to the west, both of which subduct beneath the Philippine Sea Plate. This tectonic complexity gives rise to high seismicity across the Molucca Sea to Halmahera; however, the subduction mechanisms in this region remain poorly understood. This knowledge gap is primarily due to the limited number of seismic stations, leading to a scarcity of small-magnitude earthquake data (M < 5), as well as the use of global velocity models that do not adequately represent the local subsurface structure.This study aims to update the earthquake catalog within the MSCZ region and to develop a localized 1D velocity model to enhance the understanding of subsurface structures. A dataset consisting of 714 seismic events recorded between July 2016 and August 2017 from a network of 35 seismic stations was analyzed. Initial event locations were determined using a non-linear inversion approach, resulting in the identification of 366 well-constrained events. The estimated uncertainties in event location were 8.45 km, 9.83 km, and 0.05 km in the x, y, and z directions, respectively.A minimum 1D P-wave velocity model was derived using 192 selected events with focal depths ranging from 0 to 50 km, yielding a velocity range of 4.58 km/s to 8.42 km/s. This velocity model was subsequently employed for earthquake relocation using the double-difference algorithm, resulting in 366 relocated events. The estimated uncertainties after relocation were 6.47 km, 8.27 km, and 5.85 km in the x, y, and z directions, respectively.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	1D Velocity Model, Double Difference, Earthquake, Molucca Sea Collision Zone, Seismisitas
Subjects:	Q Science > QE Geology > QE538.8 Earthquakes. Seismology
Divisions:	Faculty of Civil, Environmental, and Geo Engineering > Geophysics Engineering > 33201-(S1) Undergraduate Theses
Depositing User:	Fathan Ayu Nurridhiani
Date Deposited:	31 Jul 2025 02:15
Last Modified:	31 Jul 2025 02:15
URI:	http://repository.its.ac.id/id/eprint/124404

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