NUMERICAL SIMULATION OF THE 2018 KRAKATAU TSUNAMI GENERATED BY UNDERWATER LANDSLIDE FOR THE STUDY OF PANDEGLANG REGENCY

• Main Author: Yudicia Isnaeni, Kholillah
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/45576
• Institution: Institut Teknologi Bandung

Krakatau Tsunami 22 December 2018 until now the mechanism of generation is still being debated, so it is necessary to carry out numerical simulations of the Krakatau tsunami with several mechanisms, one of which is underwater landslides. Numerical simulations of tsunamis with underwater landslides have been investigated using the COMCOT (Cornell Multi-grid Coupled Tsunami Model) model with the NSWE (Non-linear Shallow Water Equations) and nested domains up to level 4 domains. Bathymetry data used from BATNAS and topography data from the RBI Map 1:25,000. Simulated scenarios amounted to 14 scenarios with the difference between each scenario used lies in the landslide volume, the angle of the landslide, the starting and end point of the landslide, and the duration of the landslide. Model validation uses field survey data which consists of tsunami height data and inundation data, and tide gauge data which consists of tsunami height data and tsunami wave arrival time. The tsunami hazard study was carried out using hazard parameters in the form of tsunami height and covers the Pandeglang Regency area. The results of numerical simulations of tsunamis with underwater landslides show wave symptoms in the form of peaks first which are then followed by valleys at the area in the direction of the landslide. From these 14 scenarios, it was found that scenario 10 with a volume of 0,276 km3 (L= 2450 m, W= 1500 m, T= 75 m), a landslide duration of 410 seconds, an angle of 8.2 °, and a length of 3435 m landslide path gives a tsunami height that closest to the field measurements with an error of 5%. Scenarios with smaller volumes result in lower waves and longer arrival times. A landslide angle difference of 7,7% produces tsunami waves with a arrival time of 0,7 minutes faster and tsunami height of 20-30 cm shorter for steep areas. The most significant parameter that influences the generation and propagation of tsunamis is the length of the landslide path, the longer of landslide path gives, the tsunami height higher and the arrival time faster. The arrival time of the simulation results is slower 9-10 minutes in Panjang (Lampung), 4-5 minutes in Kota Agung (Lampung), and 9-11 minutes in Ciwandan (Banten) compared to the tide gauge data. The worst affected areas with very dangerous classification (wave height that hit >3 m) are Panaitan Island, Ujungkulon, and Tanjung Lesung areas. Whereas for areas not affected by tsunami waves are Cikawung, and Citeureup till to Patia.