MalaysiaGIS.com

Source: New Straits Times

It should be shifting eastward, but since the Dec 26 earthquake, it has been moving westward.

Survey and Mapping Department data show that tidal waves from Sumatra have dragged the Sunda Plate (on which the peninsula sits) westward.

This is unusual, as the plate had been shifting eastward by 3cm every year.

The southern tip of Johor has moved 2cm westward. In the north, Langkawi has shifted 18cm westward toward the epicentre of the earthquake.

Survey and Mapping Department (Jupem) director-general Datuk Hamid Ali said the shift in land mass was not significant enough to require redrawing the map of the country.

However, Hamid said, another two major earthquakes could shift peninsular Malaysia substantially away from its current position.

The figures were obtained from the Malaysia Active GPS System (MASS) network of permanent GPS stations in 18 locations around the country.

"At present, the change is not significant enough to require a new map to be drafted," he said. "We do not know exactly when the movement of the peninsula will stop, but estimate it could be another 18 months before the earth’s crust settles."

Jupem is capturing aerial photographs to monitor changes until the movements subside.

"We cannot conclude anything from the photographs taken until we are certain that the tectonic plates have settled," he said.

The only change that may take place is a revision of co-ordinates to take account of the shift.

Hamid said the base point that marked the national maritime boundary, which had shifted due to the Dec 26 tsunami and March 28 earthquake in Sumatra, had been re-established.

At 12.30pm on Dec 26, the needles on the charting machine hit a frantic pace, recording a sudden dip of 1.02m in the sea level before rising 1.81m at 12.42pm. A typical complete tide cycle would take 12 hours.

That day, the lives of 68 Malaysians were lost off the coasts of Kedah, Penang and Perak. They were among the estimated 270,000 who perished in Indonesia, Thailand, India, Sri Lanka, Bangladesh and the Maldives.