In the wake of the 2004 Sumatra earthquake, scientists have discovered that the land in Singapore gradually sank over the following years. This revelation, published in the journal Communications Earth & Environment, is a stark reminder of the far-reaching consequences of large-scale earthquakes. While the shift was only a few millimetres annually, it underscores the importance of accounting for vertical land motion when studying sea-level rise and planning for climate change adaptation. The research, led by Nanyang Technological University (NTU), revealed that the ground continued to shift in places more than 600km away from the earthquake's epicentre. This finding highlights the potential for underestimated coastal flood risks in low-lying areas if vertical land motion is not considered. The study's lead author, Grace Ng, emphasized that massive earthquakes set off a slow adjustment deep within the Earth that can continue for years. This movement is linked to a weak mantle beneath the Earth's crust in the Sumatran backarc, the region behind Sumatra's volcanoes where Singapore, Malaysia, and Thailand are located. The team analysed ground movement data from Global Navigation Satellite System stations across Singapore, Malaysia, and Thailand, and compared these recordings with computer models of the Earth's layers. They discovered that the observed movement could only be explained if the upper mantle beneath the backarc was weak enough to flow slowly over time. This finding has significant implications for coastal planning in low-lying cities, as most current sea-level projections focus primarily on climate factors such as ice melting and ocean warming. Emma Hill, the AXA-Nanyang Professor in Earth and Environmental Science and senior author of the paper, noted that incorporating these deep geological movements into models will help improve coastal planning. However, the potential influence of earthquake-induced vertical land motion on local sea levels remains an emerging area of research, and these findings were not considered in Singapore's latest sea-level rise projections published in January 2024. The study also raises questions about the long-term impacts of earthquakes in the region. In the past, many people thought that Singapore was too far from Sumatra to be affected by earthquakes there. But as Grace Ng points out, even though Singapore is so far away, it has a weak mantle that is slowly readjusting beneath it after earthquakes in Sumatra. This means that Singapore can still experience impacts, even if they are not immediately apparent. This finding underscores the interconnectedness of our planet and the need for a more holistic approach to understanding and addressing the impacts of earthquakes and climate change. In my opinion, this study is a wake-up call for policymakers and urban planners to incorporate tectonic land height changes into local sea-level assessments and adaptation plans. While the cumulative sinking of Singapore is on the centimetre scale, it is still time for action. As Ng suggests, it is always best to incorporate these models into adaptation plans earlier rather than incurring costs by retrofitting infrastructure later. The study also highlights the importance of scientific research and collaboration in addressing global challenges. By working together, scientists, policymakers, and urban planners can develop more robust and resilient solutions to the impacts of earthquakes and climate change. In conclusion, this study is a powerful reminder of the far-reaching consequences of large-scale earthquakes and the need for a more comprehensive approach to understanding and addressing the impacts of these events. As we continue to grapple with the challenges of climate change and urban development, it is essential to remain vigilant and proactive in our efforts to protect our communities and our planet.
