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Macau tsunami hazard doubles as sea levels rise, ASE / EOS researchers show

21 Aug 2018


Sea level rise is one of the more prominent results of global warming, and an increased flooding hazard to low-lying coastal communities one of its key consequences, with many Asian coastal cities in the danger zone. But what will higher sea level mean for extreme flooding events, such as flooding induced by tsunamis? This is what Earth Observatory of Singapore (EOS) Research Fellow Linlin Li, ASE/EOS Associate Professor Adam Switzer and their collaborators at Virginia Polytechnic Institute and State University in the US and the National Taiwan University, asked. In a new study recently published in Science Advances, they show that even a modest sea level rise scenario would increase both the frequency and intensity of tsunami induced flooding in the Chinese coastal city Macau, which is considered ‘tsunami safe’ today.

The researchers used computer model simulations to find out how Macau would be affected by a tsunami triggered by a strong (8 - 9 magnitude) earthquake in the Manila Trench in the South China Sea. The results showed that at current sea level, as expected, Macau is not in danger of tsunami-induced flooding. The great surprise was that a sea level rise by just 0.5 m, as is expected by 2060, could drastically increase the frequency of tsunami-induced flooding by a factor of 1.2 – 2.4. A sea level rise of 1 m, as is expected by 2100, would correspond to an increased risk by a factor of and 1.5 – 4.7.

This study is an important reminder of that sea level rise comes with a whole set of compounding factors, such as storm surges, tsunamis and tidal variations, that policy makers, town planners, emergency services and insurance companies need to take into account to create safer coastlines. The authors hope that this study will bring attention to what a threat rising sea level poses to many Asian coastal cities. The study is part of a larger program investigating the consequences of sea level rise in other potentially future tsunami-prone coastal cities worldwide. Below are some photos from a post-typhoon survey the researchers conducted in Macau after typhoon Hato struck the city in August 2017, causing billion US$ damage as well as human fatalities.  

Link to twitter post by Associate Professor Adam Switzer here
Read the article in Science Advances here
Find out about Dr Linlin Li’s research on coastal hazards in the South China Sea region here
Find out more about Adam Switzer and the Coastal Lab here  and here

Photos from post-typhoon survey in Macau last year. Courtesy of Dr Kuifeng Zhao.