The recent study on the impact of large earthquakes in Sumatra on Singapore's land subsidence has sparked a crucial conversation about the long-term effects of geological events on our coastal cities. This research, led by Nanyang Technological University (NTU), reveals a fascinating yet concerning phenomenon: the gradual sinking of Singapore due to tremors in Sumatra, even over 600km away.
What makes this finding particularly intriguing is the revelation that the weak mantle beneath the Earth's crust in the Sumatran backarc region is responsible for this slow but steady land subsidence. This area, located behind Sumatra's volcanoes, includes Singapore, Malaysia, and Thailand, and the movement of the upper mantle is causing the Earth's crust to sink in these cities.
The study's lead author, Grace Ng, emphasizes the importance of considering this vertical land motion when assessing sea level rise and developing adaptation plans for climate change. The research, published in the journal Communications Earth & Environment, highlights that coastal flood risks in low-lying areas might be underestimated if this land subsidence is not taken into account.
One of the key insights from this study is the realization that the effects of earthquakes can have a prolonged impact on the Earth's surface. Ng explains that massive earthquakes set off a slow adjustment deep within the Earth, which can continue for years. This is a critical point, as it challenges the notion that Singapore, being far from Sumatra, is immune to the region's seismic activity.
The research also underscores the need for more comprehensive sea-level projections that consider both climate factors and geological movements. Emma Hill, the senior author, notes that current projections often focus solely on ice melting and ocean warming, neglecting the significant role of post-earthquake land sinking. By incorporating these deep geological movements, we can improve coastal planning for low-lying cities, ensuring better preparedness and resilience.
The study's findings have practical implications for Singapore's infrastructure and urban planning. While the cumulative sinking of Singapore is on the centimeter scale, it is crucial to act now. Ng suggests that policymakers should incorporate these models into adaptation plans early on to avoid incurring higher costs through retrofitting later. This is especially relevant in countries like New Zealand and the United States, which are beginning to account for these tectonic land height changes in their local sea-level assessments.
However, the study also highlights the challenges in incorporating these findings into existing projections. The Meteorological Service Singapore (MSS) under the National Environment Agency acknowledges that the potential influence of earthquake-induced vertical land motion on local sea levels is an emerging area of research. As a result, these findings were not included in Singapore's latest sea-level rise projections published in January 2024.
Despite these challenges, the study's impact on public perception is already evident. Ng hopes that the research will change how people in Singapore view the long-term impacts of earthquakes in the region. She emphasizes that the weak mantle beneath the city-state is slowly readjusting after earthquakes in Sumatra, which means Singapore is not as safe from these events as previously thought. This realization should prompt a reevaluation of the city-state's preparedness and resilience strategies.
In conclusion, this study serves as a reminder that the effects of geological events can extend far beyond the immediate disaster zone. It highlights the importance of considering both climate and geological factors in our assessments and planning for the future. As Singapore continues to face the challenges of sea level rise and climate change, this research provides valuable insights that can help shape more resilient and sustainable urban development strategies.
