AFTERSHOCKS may continue to affect the ancient Mersing Fault Zone until all tectonic energy is released, the Malaysian Meteorological Department (MetMalaysia) has said.
Its director-general, Mohd Hisham Mohd Anip, attributed the recent series of tremors in southern Johor to the long-dormant fault line, which is believed to have been reactivated due to regional tectonic stress.
“While Segamat is quite a distance from Mersing, the fault connectivity is believed to continue underground and functions as a weak zone in the Earth’s crust,” Dr Hisham told *The Star*.
“The quakes were caused by regional crustal plate pressure that disrupted the balance of the Earth’s crust in Peninsular Malaysia to the point of reactivating the ancient Mersing Fault Zone,” he added. “Aftershocks will usually ease once the site reaches equilibrium.”
The state of Johor has experienced at least five tremors in Segamat beginning with a magnitude 4.1 earthquake at 6.13am on 24 August. This was followed by tremors on 27 August (3.2), 28 August (2.5), 29 August (3.4) and 30 August (2.7). A further minor tremor was recorded near Sri Medan, Parit Sulong, on 3 September, measuring 2.9 in magnitude.
Dr Hisham noted that prior to the recent events, Johor had not experienced any seismic activity since 1874. He explained that most tremors in Peninsular Malaysia are typically the result of strong earthquakes originating from neighbouring Sumatra, Indonesia.
He further stated that earthquakes in the peninsula rarely exceed a magnitude of 5.0, and the likelihood of a major earthquake occurring is extremely low.
Dr Hisham reaffirmed the department’s commitment to continuous monitoring and timely dissemination of seismic updates.
“The tremors in Johor were weak and are not expected to bring any major impact. However, the public must always stay cautious and refer to official information from the department,” he said. - Sept 7, 2025
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