More earthquakes expected around Segamat following recent tremors, expert says

MORE seismic activity is anticipated around Segamat, following a series of tremors since 24 August, the latest being a 2.7 magnitude earthquake recorded at 7.29 AM today.

Universiti Teknologi Malaysia (UTM) expert in Earthquake Engineering Professor Dr Azlan Adnan said on Saturday that while aftershocks may continue, there is also the possibility of a larger earthquake exceeding magnitude 5 on the Richter scale.

"In earthquake science and engineering, there are three categories of tremors: 'foreshock', 'mainshock', and 'aftershock'," explained Azlan.

"If the M4.1 earthquake is the 'mainshock' – a common occurrence – aftershocks will likely follow, with lower magnitudes, less than M4.1. These can persist for days, weeks, or even months, as seen in Bukit Tinggi after the M4.7 earthquake from 2007 to 2009."

He added, "If the M4.1 earthquake is a 'foreshock', indicating a larger quake, we could experience a stronger tremor, possibly exceeding M5."

At present, it remains unclear whether the M4.1 tremor is a 'mainshock' or 'foreshock'. "The issue now is that we cannot determine whether the M4.1 event is the 'mainshock' or a precursor to a larger earthquake until a stronger tremor occurs in the coming years," he said.

Azlan also emphasised that the possibility of further seismic activity remains high, urging all parties to stay vigilant.

"Monitoring and inspection of building structures should be prioritised, particularly as many buildings in the country were not designed to withstand earthquakes," he added.

When asked about the potential role of human activities in triggering the earthquakes, Azlan clarified that small tremors could be induced by human activities, such as quarry explosions, groundwater pumping, or changes in reservoir levels.

However, he noted that the current pattern of seismic activity in Segamat, which began with the M4.1 tremor followed by five aftershocks up to M2.7 at a shallow depth of around 10 km, aligns more closely with natural fault movements.

"Quarry explosions are typically shallow, their waves are rapid, and they rarely cause a series of aftershocks lasting for days," he said. "In short, while human activity may amplify the tremors, the main cause in Segamat appears to be the reactivation of an existing fault."

He recommended that quarry data, including the timing and location of explosions, be cross-referenced with seismic activity to rule out the possibility of the tremors being caused by quarry blasts. - August 30, 2025