KOTA KINABALU: While Sabah experiences occasional tremors, the phenomenon is not making the state sink, say geologists.
According to Emeritus Prof Dr Felix Tongkul, while tectonic plate movements can cause land to move up, down or sideways, he is not aware of how the 2004 Sumatra quake, officially known as the 2004 Indian Ocean earthquake and tsunami, had affected Sabah.
He was responding to a recent article in scientific journal Communications Earth & Environment based on a study led by the Nanyang Technological University (NTU) that said the 9.2-magnitude earthquake off the coast of Sumatra had led to Singapore’s land mass to subside gradually in following years.
The study found large tremors in Sumatra have caused land to dip not just in the republic, but also Malaysia and Thailand, and continued to shift even in places more than 600km away from where the earthquakes occurred.
Tongkul said Sabah, which is out of the 600km range, has a different geological setting compared to the peninsula.
“So, I would think that this minute sinking of land due to extension of the earth’s crust associated with subduction of the oceanic crust under Sumatra does not affect Sabah.
“However, Sabah is experiencing continuous minute land movements (at a rate of a few millimetres annually) due to continued plate movements,” he said while explaining that this means there are land movements in various directions, either up or down, in certain areas of the state.
The NTU-led study further stated that while the shift was just up to several millimetres per year, it was vital to take such measurements into account when studying sea level rise and developing plans for adapting to climate change.
Universiti Malaysia Sabah (UMS) geologist Prof Rodeano Roslee said while Sabah is not sinking as a whole, there are land movements due to quakes, aftershocks and post-seismic adjustment.
Post-seismic activity refers to geological adjustments, deformations and tremors that occur after a major earthquake.
The UMS dean of the Faculty of Science and Technology said unlike the peninsula, Sabah is close to active tectonic zones associated with the Philippine Sea Plate, the Sulu Trench, the Cotabato Trench and regional active faults.
“Consequently, Sabah experiences active crustal deformation, local earthquakes and landslides,” Prof Rodeano said when contacted.
He said while Singapore experiences relatively small post-seismic subsidence caused mainly by distant Sumatra megathrust earthquakes, Malaysia, especially Sabah, faces a more complex situation where both regional tectonics and local geological processes contribute to vertical land motion.
“This makes continuous monitoring with Global Navigation Satellite System essential for accurate assessments of coastal flooding, infrastructure stability and long-term disaster resilience,” he said.
