Scenario-based numerical modelling and the palaeo-historic record of tsunamis in Wallis and Futuna, Southwest Pacific

Lamarche, Geoffroy; Popinet, Stéphane; Pelletier, Bernard; Mountjoy, Joshu; Goff, James; Delaux, S.; Bind, Jochen

doi:10.5194/nhessd-3-2283-2015

Cited by 2 publications

(4 citation statements)

References 62 publications

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“…We only present a selected number of the 15 scenarios run in this study, which are most relevant for advancing our understanding of the tsunami hazard in W&F (Table 4). All scenarios are presented in Lamarche et al (2013).…”

Section: Resultsmentioning

confidence: 99%

“…Scenario 7 is based on the 29 September 2009 rupture using parameters from Beavan et al (2010) and Lay et al (2010). These parameters were validated against posttsunami observations made in Samoa and are further validated in this paper against our observation in Futuna-Alofi .…”

Section: Tonga Trenchmentioning

confidence: 88%

“…Whereas some incidental observations and research on tsunamis has taken place in Futuna and Alofi (Capecchi, 1995;Louat et al, 1989b;Monzier et al, 1993), there has been no such studies on Wallis. Further work was undertaken for the territorial administration of W&F and presented in an unpublished report (Lamarche et al, 2013). This paper documents the tsunami hazards in Wallis and in Futuna from the generation and interpretation of 15 numerical models for scenarios affecting both archipelagos.…”

Section: Introductionmentioning

confidence: 91%

“…The most recent tsunami to have struck Futuna occurred on 30 September 2009 (local time). It was generated by the 29 September 2009 South Pacific M W = 8.1 earthquake that occurred on the northernmost tip of the Tonga Trench (Beavan et al, 2010;Lay et al, 2010) (Fig. 1).…”

Section: Historical Tsunamismentioning

confidence: 99%

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Scenario-based numerical modelling and the palaeo-historic record of tsunamis in Wallis and Futuna, Southwest Pacific

Lamarche

Popinet²,

Pelletier³

et al. 2015

Nat. Hazards Earth Syst. Sci.

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International audienceWe investigated the tsunami hazard in the remote French territory of Wallis and Futuna, Southwest Pacific, using the Gerris flow solver to produce numerical models of tsunami generation, propagation and inundation. Wallis consists of the inhabited volcanic island of Uvéa that is surrounded by a lagoon delimited by a barrier reef. Futuna and the island of Alofi form the Horn Archipelago located ca. 240 km east of Wallis. They are surrounded by a narrow fringing reef. Futuna and Alofi emerge from the North Fiji Transform Fault that marks the seismically active Pacific-Australia plate boundary. We generated 15 tsunami scenarios. For each, we calculated maximum wave elevation (MWE), inundation distance and expected time of arrival (ETA). The tsunami sources were local, regional and distant earthquake faults located along the Pacific Rim. In Wallis, the outer reef may experience 6.8 m-high MWE. Uvéa is protected by the barrier reef and the lagoon, but inundation depths of 2–3 m occur in several coastal areas. In Futuna, flow depths exceeding 2 m are modelled in several populated areas, and have been confirmed by a post-September 2009 South Pacific tsunami survey. The channel between the islands of Futuna and Alofi amplified the 2009 tsunami, which resulted in inundation distance of almost 100 m and MWE of 4.4 m. This first ever tsunami hazard modelling study of Wallis and Futuna compares well with palaeotsunamis recognised on both islands and observation of the impact of the 2009 South Pacific tsunami. The study provides evidence for the mitigating effect of barrier and fringing reefs from tsunamis

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Section: Resultsmentioning

confidence: 99%

Section: Tonga Trenchmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 91%

Section: Historical Tsunamismentioning

confidence: 99%

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Scenario-based numerical modelling and the palaeo-historic record of tsunamis in Wallis and Futuna, Southwest Pacific

Lamarche

Popinet²,

Pelletier³

et al. 2015

Nat. Hazards Earth Syst. Sci.

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Tsunami hazard potential for the equatorial southwestern Pacific atolls of Tokelau from scenario-based simulations

Orpin¹,

Rickard²,

Gerring³

et al. 2015

Preprint

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Abstract. Devastating tsunami over the last decade have significantly heightened awareness of the potential consequences and vulnerability to tsunami for low-lying Pacific islands and coastal regions. Our tsunami risk assessment for the atolls of the Tokelau Islands was based on a tsunami source–propagation–inundation model using Gerris Flow Solver, adapted from the companion study by Lamarche et al. (2015) for the islands of Wallis and Futuna. We assess whether there is potential for tsunami flooding on any of the village islets from a series of fourteen earthquake-source experiments that apply a combination of well-established fault parameters to represent plausible "high-risk scenarios" for each of the tsunamigenic sources. Earthquake source location and moment magnitude were related to tsunami wave heights and tsunami flood depths simulated for each of the three atolls of Tokelau. This approach was adopted to yield indicative and instructive results for a community advisory, rather than being fully deterministic. Results from our modelling show that wave fields are channelled by the bathymetry of the Pacific basin in such a way that the swathes of the highest waves sweep immediately northeast of the Tokelau Islands. From our series of limited simulations a great earthquake from the Kuril Trench poses the most significant inundation threat to Tokelau, with maximum modelled-wave heights in excess of 1 m, which may last a few hours and include several wave trains. Other sources can impact specific sectors of the atolls, particularly from regional sources to the south, and northern and eastern distant sources that generate trans-Pacific tsunami. In many cases impacts are dependent on the wave orientation and direct exposure to the oncoming tsunami. This study shows that dry areas remain around the villages in nearly all our "worst-case" tsunami simulations of the Tokelau Islands. Consistent with the oral history of little or no perceived tsunami threat, simulations from the recent Tohoku and Chile earthquake sources suggest only limited flooding. Where potential tsunami flooding was inferred from the modelling, recommended minimum evacuation heights above local sea level were compiled, with particular attention paid to variations in tsunami flood depth, subdivided into directional quadrants around each atoll. But complex wave behaviours around the atolls, islets, tidal channels and lagoons were also observed in our simulations. Wave amplitudes within the lagoons may exceed 50 cm, increasing any inundation and risks on the inner shoreline of the atolls, which may influence evacuation strategies. Our study shows that indicative, but instructive, simulation studies can be achieved even with only basic field information, due in part to the relative simplicity of the atoll topography and bathymetry.

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Scenario-based numerical modelling and the palaeo-historic record of tsunamis in Wallis and Futuna, Southwest Pacific

Cited by 2 publications

References 62 publications

Scenario-based numerical modelling and the palaeo-historic record of tsunamis in Wallis and Futuna, Southwest Pacific

Scenario-based numerical modelling and the palaeo-historic record of tsunamis in Wallis and Futuna, Southwest Pacific

Tsunami hazard potential for the equatorial southwestern Pacific atolls of Tokelau from scenario-based simulations

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