Abstract Database

Tsunami Simulation and Hazard Assessment along the Coasts of Fiji

Rawaikala Unaisi Rabetabeta
Supervisor: Bunichiro SHIBAZAKI, Yushiro FUJII
Country: Fiji

This study was aimed to assess the tsunami hazard around the coastline of Fiji, in terms of the tsunami heights and tsunami arrival times. Eleven hypothetical source models were considered along the Tonga Trench of which six had Mw 8.0 and five had Mw 8.5. The five source earthquakes considered for the Vanuatu Trench had Mw of 8.0. The fault parameters were determined considering the worst case scenario using Papazacho’s scaling law while the tsunami propagation was computed numerically using the TUNAMI- N2 code.

The expected travel time of tsunami from the Tonga trench is about 63 minutes for an earthquake source of Mw 8.0 and 56 minutes for a source of Mw 8.5. Tsunami high risk areas from any tsunami source along the Tonga Trench were identified to be the Lau Islands, Pacific Harbor and the Vanua Levu coastlines particularly Udu and Natewa Bay. The earliest tsunami arrival time from the New Hebrides Trench is 91 minutes. Tsunami high risk areas were identified to be the coasts of Malolo Lailai in the Mamanuca Group, Yalobi in the Yasawa Islands, Vunisea Kadavu, Pacific Harbor and the coral coast of Viti Levu particularly Korotogo and Natadola.

Generally it can be inferred that a major reason of the relatively high tsunami height is that some of these coastlines are within range of maximum directivity of the tsunami, thus, there is little scattering of tsunami energy. In addition, reflection and refraction phenomenon taking place amplifies the tsunami heights at some of these locations.

Citation: Bulletin of IISEE, 45, 103-108.