KUALA LUMPUR: An old fault line, inactive for hundreds of years, is believed to have caused a series of weak earthquakes recently recorded in Johor.
On Aug 24, a 4.1-magnitude earthquake was detected in Segamat at 6.13am, followed by a second tremor measuring 2.8 magnitude in Yong Peng, about 28km northwest of Kluang, on Aug 27.
A third quake, measuring magnitude 3.2, was recorded at 8.59am on Wednesday, centred about 18km south of Segamat.
A fourth quake of magnitude 2.5 was detected at 7.56pm on Thursday, followed by a fifth tremor at 4.24am yesterday, measuring 3.4 magnitude at a depth of 10km.
Malaysia had previously reported weak earthquakes in Kuala Pilah, Negri Sembilan, in 1987 and 2009.
The strongest earthquake recorded in the country was a magnitude 5.9 tremor in Ranau and Kundasang, Sabah, which also affected Mount Kinabalu and claimed 18 lives.
The recent rise in tremors has sparked concerns over whether Malaysia is no longer “immune” to earthquakes and if the country is adequately prepared should stronger quakes strike in the future.
Although Malaysia is not located within the Pacific Ring of Fire, it lies close to active tectonic regions, including the Sumatra and Sunda Megathrust fault lines to the west, and the Sulu-Celebes Sea fault lines to the east.
Movements of tectonic plates – such as the collision between the Indo-Australian and Eurasian plates – can trigger tremors in Peninsular Malaysia.
Universiti Kebangsaan Malaysia geology programme head Associate Professor Dr Mohd Rozi Umor said the Johor earthquakes were linked to an old fault line that was active about 200 million years ago.
The fault line was formed during the creation of the Titiwangsa mountain range.
“Effects from regional tectonic systems have the potential to reactivate old fault lines in Peninsular Malaysia, which could cause small- to medium-scale earthquakes.
“Apart from the Mersing Line, the Ulu Bendul Line is also believed to be active, as evidenced by a series of weak tremors in Kuala Pilah in 1987 and 2009,” he said.
He said earthquake risks in Malaysia could be divided into high-risk and low-risk zones.
Sabah is considered the country’s primary high-risk area, particularly Ranau and Kundasang (around Mount Kinabalu).
“Tawau, Lahad Datu and Kota Marudu are also high-risk areas as they are close to the Sulu Sea and Celebes Sea fault lines.
“Peninsular Malaysia and Sarawak are classified as medium-risk zones, especially along the west coast, including Perak, Selangor, Negri Sembilan, Melaka and western Johor.
“These areas could be affected by major earthquakes originating from Sumatera, such as those linked to the Sumatera Fault and Sunda Megathrust Subduction Zone,” he said.
© New Straits Times Press (M) Bhd
