NHESSD Natural Hazards and Earth System Sciences Discussions NHESSD Nat. Hazards Earth Syst. Sci. Discuss. 2195-9269 Göttingen, Germany 10.5194/nhessd-1-1823-2013 Tsunami hazard in La Réunion island from numerical modeling of historical events Quentel E. 1 Loevenbruck A. 1 Hébert H. 1 Allgeyer S. https://orcid.org/0000-0003-4864-0181 1 2 CEA, DAM, DIF, 91297 Arpajon, France now at: The Australian National University, Research School of Earth Sciences, Canberra 0200, Australia 08 05 2013 1 3 1823 1855 Copyright: © 2013 E. Quentel et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://nhess.copernicus.org/preprints/1/1823/2013/nhessd-1-1823-2013.html The full text article is available as a PDF file from https://nhess.copernicus.org/preprints/1/1823/2013/nhessd-1-1823-2013.pdf

Whereas major tsunamis have recently affected the southwest Indian Ocean, tsunami hazard in this basin has never been thoroughly examined. Our study contributes to fill in this lack and focuses on La Réunion island for which tsunami hazard related to great earthquakes is evaluated by modeling the scenarios of major historical events. Then, our numerical modeling allow us to compare the tsunami impact at regional scale according to the seismic sources; we thus identify earthquakes locations which most affect the island and describe the impact distribution along its coastline. Thirdly, detailed models are performed for selected sites based on high resolution bathymetric and topographic data; they provide estimations of the water currents, wave heights and potential inundations. When available, field measurements and tide records allow testing our models. Arrival time, amplitude of the first wave and impact on the tide gauge time series are well reproduced. Models are consistent with the observations. The west coast of La Réunion is the most affected (to 2.7 m in the harbour of Le Port Est for 2004 event) by transoceanic tsunamis. Numerical modeling has been performed at Saint-Paul for the 2004 Sumatra-Andaman event and 1833 Sumatra event; the low topography of this town could make it vulnerable to tsunami waves. Harbours, particularly prone to undergo significant damages, are also examined. Outside the harbours as well as at Saint-Paul, inundations are predicted along the coastline due to important local wave heights (> 2.5 m).

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