Seismic study of Singapore could guide urban construction and renewable energy development

(Press-News.org) A new seismic study of Singapore could guide urban growth and renewable energy development in the coastal city nation, where 5.6 million residents live within an area of 734 square kilometers.

The study, published in Seismological Research Letters, identifies areas with increased risk of ground shaking and a possible reservoir for geothermal energy production, as well as a glimpse at Singapore’s tectonic history.

Jiayuan Yao of China University for Geosciences and colleagues analyzed teleseismic data captured by a few permanent seismic stations and a nodal seismic array deployed in 2019 around the city. Their results provide the first detailed look at the top-kilometer depth of sediment.

“These data are invaluable for assessing potential seismic hazards,” said Yao. “Our findings suggest that areas with soft sediments, especially the reclaimed land in eastern Singapore, are likely to experience higher seismic ground motion amplification.”

About 20% of urban Singapore consists of reclaimed land, where sand has been added and areas pumped dry to expand the amount of useable land. Seismic waves passing through these soft sediments grow stronger in amplitude, leading to stronger shaking that is more likely to damage infrastructure.

Singapore lies a few hundred kilometers east of the high seismic hazard Sunda megathrust zone, which produced the 2004 Indian Ocean earthquake and tsunami that killed nearly 230,000 people. Yao and colleagues note that a better understanding of ground shaking in Singapore can help prepare the nation for future large regional earthquakes.

“These findings of ground motion amplification underscore the importance of considering local geological conditions in seismic risk evaluation and smart city construction,” said Yao, who noted that that the research team may submit a formal report on their findings to the Singapore government.

In their study, Yao and colleagues also uncovered an area of relatively low seismic velocity beneath Sembawang Hot Spring in the northern part of Singapore, stretching from the surface to about 5 kilometers deep. The anomaly indicates a heat source in the deep crust below the spring. High mantle heat flow could be the source, the researchers noted, although they can’t rule out the possibility of heat produced by radioactive elements in the underlying granite.

Cracks in the granite might be exploited to use the heat source for geothermal energy production, Yao and colleagues suggest, but a denser nodal array should be deployed around the spring to get a better look at the subsurface.

The researchers combined their results with earlier geological surveys to reconstruct a possible tectonic history for Singapore. The crustal bedrock across central and eastern Singapore is likely the result of magmatic intrusion generated by the subduction of the Paleo-Tethys oceanic slab below the East Malaya Terrane roughly 250 to 230 million years ago. Sediments in western Singapore were deposited around 230 to 220 million years later as part of the Sukhothai volcanic island arc system.

Yao said the research team would like to collect and analyze ambient noise data next to investigate shallow subsurface structures in Singapore and “measure small changes of seismic velocity to track changes in water storage at depth.”

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