Ni'mah, Kafa 'Aisyana (2023) Estimasi Overpressure Melalui Analisis Data Kecepatan pada Zona Subduksi di Bagian Barat Palung Nankai, Jepang. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Zona subduksi merupakan salah satu daerah yang memiliki potensi gempa yang besar. Palung Nankai di Jepang adalah daerah dengan zona subduksi di mana catatan gempa terarsip dengan baik, meskipun dengan kompleksitasnya. Juga, gempa bumi lambat telah terdeteksi di zona ini selama 20 tahun terakhir. Ada banyak peluang untuk mengetahui dinamika dan deformasi dalam setting aktif tersebut. Untuk memperluas pemahaman tentang gempa slip lambat yang mungkin terjadi dan memicu gempa yang lebih besar, penelitian ini ingin menyimpulkan hubungan antara overpressure, salah satu keadaan dan sifat zona seismogenic, dan tremor, salah satu jenis gempa lambat. Untuk menjalankan penelitian ini, digunakan 4 model kecepatan garis kegempaan yang diambil di Hyuga-nada. Dan data getaran terekam yang ditempatkan di sekitar garis berasal dari Yamashita. Penelitian ini mencoba mengkorelasikan fenomena overpressure dan tremor. Model Vp dikonversi menjadi porositas menggunakan persamaan Wyllie untuk memprediksi kondisi tekanan pori di area tersebut, kemudian akan digunakan untuk fitting. Dengan mengasumsikan ada lokasi yang tepat mengikuti kurva pemadatan normal sebagai fungsi tegangan efektif, maka dapat digunakan untuk memperkirakan tekanan berlebih. Overpressure ekonomis dengan membandingkan porositas yang diamati dan kurva referensi dengan kedalaman yang sama di bawah dasar laut. Potensi overpressure yang terjadi mungkin berhubungan dengan area Vp yang rendah. Estimasi overpressure berada pada kisaran 1,2 hingga 12 MPa pada kisaran kedalaman 700 hingga 4000mbsf. Diantaranya diperkirakan berada di sekitar gunung laut. Penelitian ini juga menyimpulkan bahwa zona overpressure ini tumpang tindih dengan lokasi tremor, meskipun perkiraan nilai overpressure juga masih belum pasti karena ketidakpastian nilai kerapatan yang digunakan di sini.
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Subduction zone is one of area which has great potential of earthquake. Nankai trough in Japan is such an area with subduction zone where earthquake records are well archived, although with its complexity. Also, slow earthquakes have been detected in this zone over the past 20 years. There are many opportunities to know the dynamic and deformation in such an active setting. To expand the understanding about slow slip earthquake which might occur and trigger a bigger earthquake, this study wants to infer the relationship between overpressure, one of state and properties of the seismogenic zone, and tremors, one of slow earthquake’s type. To run this research, 4 velocity model of seismicity lines taken in Hyuga-nada are used. And the recorded data tremors which placed around the lines are from Yamashita. This research tries to correlate the overpressure phenomena and the tremors. Vp models are converted to the porosity using Wyllie equation to predict the pore pressure condition in the area, then it will used for fitting. By assuming there are appropriate location follows a normal compaction curve as a function of effective stress, then it can be used for estimating the overpressure. Overpressure was estimated by comparing observed porosity and the reference curve with the same depth below seafloor. The potential overpressure occurred might has relationship with the low Vp area. Estimated overpressure is in the range of 1.2 to 12 MPa at a depth range of 700 to 4000mbsf. Among them are predicted to be around seamounts. This research also infer that these overpressure zones overlap the tremor location, although the overpressure value estimated also still uncertain because the uncertainty density value used here.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | Nankai, Overpressure, Porositas, Zona Subduksi Porosity, Overpressure, Subduction Zone, Nankai |
| Subjects: | G Geography. Anthropology. Recreation > GC Oceanography > GC89 Sea Level Q Science > Q Science (General) > Q180.55.M38 Mathematical models Q Science > QE Geology > QE538.8 Earthquakes. Seismology Q Science > QE Geology > QE539.2.S4 Seismic models T Technology > T Technology (General) > T57.5 Data Processing T Technology > TA Engineering (General). Civil engineering (General) > TA357 Computational fluid dynamics. Fluid Mechanics T Technology > TH Building construction > TH1095 Earthquakes and building |
| Divisions: | Faculty of Civil Engineering and Planning > Geophysics Engineering > 33201-(S1) Undergraduate Thesis |
| Depositing User: | Kafa 'Aisyana Ni'mah |
| Date Deposited: | 21 Aug 2023 05:25 |
| Last Modified: | 21 Aug 2023 05:25 |
| URI: | http://repository.its.ac.id/id/eprint/103635 |
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