Probabilistic tsunami hazard and exposure assessment for the pacific islands- Fiji

Abstract

Tsunami are known to be one of the most powerful and destructive natural hazards to impact low-lying coastal communities. The Republic of Fiji is situated in a complex tectonic setting at the boundary of two active plates in the South-west Pacific; the Indo-Australian and Pacific Plate, making the country highly vulnerable to earthquakes and tsunami. Local and regional source tsunami is a concern for emergency management. This is due to the limited warning time in receiving a tsunami alert and issuing warnings to the public. Fiji's greatest local and regional tsunami hazard risk is from the Tonga-Kermadec trench and South New Hebrides faults. This paper presents the first probabilistic tsunami hazard assessment of a credible 1 in 10,000 year event for Fiji's two largest populated islands, Viti Levu and Vanua Levu. Subsequent to the probabilistic tsunami hazard assessment, this paper presents the results of a tsunami exposure assessment of the population, assets and critical infrastructure vulnerable to tsunami inundation from Tonga-Kermadec and South New Hebrides tsunami sources. This study applies a mix methodology approach, using a combination of hydrodynamic models, probabilistic approaches, Geographic Information Systems and quantitative analysis to determine maximum tsunami heights and exposure to tsunami hazard. Results of the exposure assessment indicates provinces in Vit Levu and Vanua Levu are likely to be susceptible to various tsunami inundation heights, concluding that people and assets in provinces such as Macuata and Tailevuare more vulnerable to tsunami. The results of this study provides valuable information for the Government of Fiji specifically the National Disaster Management Office, Mineral Resources Department, the National Tsunami Warning Centre and at risk communities. This will increase tsunami risk knowledge and will encourage decisive warning times and allow emergency management to make informative decision-making in regards to emergency preparedness and response planning.