Tsunami inundation modelling of parts of Espiritu Santo and Efate, Vanuatu

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Wang, X.; Power, W.L.; Lukovic, B.; Heron, D.W. 2016 Tsunami inundation modelling of parts of Espiritu Santo and Efate, Vanuatu. Lower Hutt, N.Z.: GNS Science. GNS Science report 2015/63 40 p.

Abstract: Potential tsunami impact on the southern coasts of Espiritu Santo and Efate, Vanuatu, including maximum flow depth and inundation extent, has been evaluated via numerical simulations using plausible ‘worst case’ seismic scenarios in a variety of source regions. The source regions include the New Hebrides Trench and its back-arc region, the Tonga Trench region, and those major subduction interfaces along the Pacific Rim with orientations that will direct tsunami energy toward the southwest Pacific islands. The modelling results show that, of the scenarios modelled, an Mw9.4 earthquake on the New Hebrides Trench would pose the most devastating impact on the coasts of Vanuatu. Most low-lying areas of the southern coasts of Espiritu Santo and Efate would be heavily flooded, up to 5.0 km inland inside Teouma Bay of Efate, should such an event occur. Among all the Mw9.4 distant source scenarios along the Pacific Rim, those from the Chile-Peru Trench were found to pose less tsunami threat to Vanuatu than the other distant sources, due to the shielding effects of submarine ridges in association with Tonga Kermadec trench and the south Pacific islands such as Tonga and Fiji islands on the path way of tsunami. The modelling results and findings help to understand the potential tsunami threat in Vanuatu from different source regions, and contribute to tsunami evacuation mapping and hazard mitigation in Vanuatu. (auth)