Coral reef response in the Maldives during the 2004 Indian Ocean tsunami

Abstract

The impact of tsunamis on buildings or infrastructures has been globally studied. However, the relationship tsunami waves-marine ecosystems remains unclear. During the 2004 Indian Ocean Tsunami (IOT), damage to coral reefs were surveyed in the Maldives. Coral reef system is essential for fisheries, tourism and represent a natural coastal protection against large waves events, so it is urgent to better understand how the IOT impacted such an ecosystem. First, we reproduce the tsunami hydrodynamic characteristics along the Maldivian shores using TUNAMI-N2 model. We then define a database gathering all the post-tsunami reef datapoints. Third, we develop fragility curves for the reefs that have been impacted by the tsunami, based on the Global Earthquake Model (GEM) guidelines, for the maximum amplitude and flow velocity of the IOT. For example, when the amplitude and the flow velocity are higher than 1 m and 1 m/s, the probability to impact the reefs is 50%. Finally, we present a reef vulnerability map in Malé City and one of its surrounding Marine Protected Areas (MPAs). This work is the first attempt to quantify the tsunami impact on coral reefs using fragility curves. Based on the 2004 IOT, we aim to provide a better understanding of the reef response during a tsunami attack. These findings have implications for the development of long-term reef monitoring and strategies to enhance reef resilience against future tsunamis.