Ranau earthquake-generating fault line was highlighted years ago

We shouldn’t have been too surprised by the recent earthquake and tremors in Sabah. There had been ample warning of the prevalence of earthquake faults in the state, and our rescue services have no reason to be unprepared.

The former director of the Minerals and Geosciences Department Sabah, Alexander Yan, had warned, apparently in 2010, that several previously identified active or potentially active faults were confirmed as earthquake-generating faults. He pointed out that “these faults are to be found in the Ranau area within the Central-North Seismic Zone of Sabah, as well as in the Dent-Semporna Peninsula Zone.”

The faults in Sabah are known as Mensabang (Ranau-Kundasang), Perancangan (east of Ranau), Lahad Datu, Keningau, Danum, Binuang, Tabin (Dent peninsula) and Beluran (Labuk Valley), wrote Yan in the abstact of a paper published on the website of the Malaysian Meteorological Department. The URL of the website suggests that the abstact was uploaded in 2010.

In Sarawak, the faults are at Tubau (Belaga to Niah) and Kelawit, according to Yan. (Belaga is not too far from the massive Bakun Dam.)

Over in the peninsula, he said it is possible that the Bukit Tinggi Fault has been reactivated, he added.

Bukit Tinggi in Pahang, just 30km from Kuala Lumpur, was reportedly hit by more than 20 earthquakes with a 2.0-3.5 magnitude from 2007 to 2009.

Peninsular Malaysia is near two active sources of earthquakes: the Sumatran fault (350km away) and the Sumatran Subduction Zone (500km away). It was previously reported that the Bukit Tinggi fault could have been reactivated by the Indonesian earthquakes.

Now, some 50000 people visit the Bukit Tinggi area daily. Are we prepared for more serious earthquakes here? Are the buildings in the area earthquake-proof? What if the road to Bukit Tinggi is closed due to landslides or fallen boulders and the cable cars are inoperable, how are those in stranded in Bukit Tinggi to be evacuated to hospitals?

This is the abstract of the paper published on the Met Department website:

EARTHQUAKE-GENERATING FAULTS IN MALAYSIA
Alexander S W Yan
Minerals and Geoscience Department Malaysia, Sabah

Abstract
Recent seismic activities (from 2007 to 2010) in Malaysia, particularly in Sabah have led to the identification of a number of earthquake-generating faults, as well as active and potentially active faults that can generate earthquake.

Several faults in Sabah that have been identified earlier as active or potential active faults have now been confirmed as earthquake-generating faults. These faults are found in the Ranau area within the Central-North Seismic Zone of Sabah, as well as in the Dent-Semporna Peninsula Zone.

In the Ranau-Kundasang area, the Mensaban Fault, which was believed to be active, has recently generated earthquakes of magnitude of 3.4Mb in July 2009. In April 2010, the N-S trending Perancangan Fault situated at 12km east of Ranau has produced an earthquake of 2.9 Mb magnitudes.

The E-W trending Lahad Datu Fault which produced a destructive earthquake in 1976 of magnitude of 5.8 Mb has recently generated an earth quake of 4.5 Mb in April 2008. This steeply-dipping normal fault is also found to be very active, where many roads along the fault zone have shown signs of movement and displacement and buildings showing severe cracking of the structure.

The 36km long Keningau Fault, which is considered active, has been identified as an earthquake-generating fault. It generated an earthquake of 3 Mb magnitudes in February 2010. This normal fault, which is part of the Crocker fault zone, was also found to extend 24km further to the south-west.

Two other faults, the Danum Fault and the Binuang Fault in the Segama Valley, which were not recognised earlier as active faults, have now been identified as earthquake-generating faults. The Danum Fault produced an earthquake of 3.3Mb in Nov 2008, whereas the Binuang Fault has generated an earthquake of 4.3 Mb in May 2008.

The active Tabin Fault in the Dent Peninsula and the Beluran Fault in the Labuk Valley have very recently generated earthquake of 4 and 4.3Mb respectively.

In Sarawak, earthquake-generating faults that have been identified are the active Tubau Fault and the Kelawit Fault. The 100km long, N-S trending strike-slip Tubau Fault, which extends from Belaga in the south to Niah in the nor
th, has generated earthquakes of 5.2Mb and 3.5Mb in May 2004 and January 2010 respectively.

In Peninsular Malaysia, a series of weak earth tremors of magnitude ranging from 2.9 to 3.5Mb that were felt in the Bukit Tinggi area from November 2007 to 25 May 2008 and in October 2009, were attributed to the possibility of the re-activation of the Bukit Tinggi Fault. It is possible that this fault could have been an earthquake-generating fault in the past.

Thanks to Don Anamalai for the video link and JJ for the heads up on Alexander Yan’s report.