Electronic Theses and Dissertation

Keaktifan gempa bumi dan tsunami di Sumatra diketahui bersumber dari Zona Subduksi Pantai Barat Sumatra. 90% kejadian gempa bumi dan tsunami terjadi akibat aktivitas zona subduksi. Sejak tahun 2004, upaya pengurangan risiko bencana gempa bumi dan tsunami dilakukan dengan banyak kajian, salah satunya dengan mengidentifikasi zona potensi gempa bumi dan tsunami masa depan. Penelitian ini bertujuan untuk mengidentifikasi potensi gempa bumi dan tsunami berdasarkan perubahan stress seismik dan energi potensial gempa bumi berdasarkan data kejadian gempa bumi tahun 2004 s.d. tahun 2019. Beberapa tahapan dilakukan pada penelitian ini diantaranya menghasilkan data hiposenter yang akurat dan presisi menggunakan metode Double Difference (DD), identifikasi parameter seismiki (b-value dan a-value), dan analisis perubahan tegangan seismik. Hasil penelitian mengungkapkan bahwa bagian utara zona subduksi memiliki waktu akumulasi stress yang lebih lama dibandingkan bagian tengah dan selatan. Informasi waktu akumulasi tegangan seismik berkesesuaian dengan ditemukannya zona potensi gempa bumi pembangkit tsunami di Zona Pantai Barat Aceh, Zona Pantai Barat Nias, dan Zona Pantai Barat Bengkulu. Merujuk pada hasil analisis probabilitias energi potensial, Gempa bumi tahun 2004 dengan kekuatan Mw 9.3 diperkirakan terkumpul dalam kurun waktu 100 tahun dengan probabilitas terlampaui sebesar 63% dalam 100 tahun. Pemodelan tsunami dengan tutupan lahan terbaru menghasilkan potensi bahaya tsunami di Kota Calang, Aceh Jaya dengan ketinggian tsunami lebih dari 12 meter dengan probabilitas terlampaui sebesar 93% dalam 100 tahun.

One of the sources of the tsunami in Sumatra was an earthquake in the West Coast Subduction Zone of Sumatra. Since 2004, disaster risk reduction effort of tsunami have been carried out in many ways, including by identifying potential tsunami zones in the future. This study aims to identify potential tsunamis generated by earthquakes based on seismic stress changes and earthquake potential energy using accurate and precise earthquake data. Several methods were carried out in this study including relocating earthquake data using the Double Difference (DD), identifying seismic parameters by frequency and magnitude distribution (b-values and a-values), analyzing seismic stress changes and earthquake potential energy. The development of a tsunami model with coastal and settlement typologies for a tsunami mitigation action plan was also carried out in this study. The results revealed that the northern part of the subduction zone is more elastic than the central and southern. This is evidenced by the potential accumulation of earthquake energy in the northern, which is greater (Mw>8) than the central and southern sections. Meanwhile, the results of the analysis of seismic stress changes show potential tsunami zones on the West Coast of Aceh, West Coast of Nias, and West Coast of Bengkulu. Referring to the results of the potential energy probability analysis, the 2004 earthquake with a magnitude of Mw 9.3 is estimated to have accumulated within 100 years with a 63% probability of exceedance in 100 years. Tsunami modeling with the latest land cover and magnitude variations (Mw 8.7 - Mw 9.3) produces a potential tsunami hazard in Calang City, Aceh Jaya with a tsunami height of more than 12 meters with a 93% probability of exceedance in 100 years.