How the quake affects Malaysia
By LOH FOON FONGIs Malaysian coastline affected by the Dec 26 quake?
Prof John Kunaraj, a geologist at Universiti Malaya, doesn’t think so.
“Only places near the epicentre where the surface ruptured will see a change in topography,” he says. “Aceh and West Sumatra are likely to be affected. The Andaman islands and Nicobar archipelago of India may have moved a little towards the west while West Sumatra on the Indian Ocean may have moved a little eastward, both by a few cm.”
But not Malaysia, not even Penang, because “it is too far from the epicentre for it to have such major impact,” he says.
Prof Kunaraj says the Indian Ocean could have become deeper by 1m but that would not affect shipping. “For the quake to have any geological impact, the depth of change has to be bigger than that. The 1964 earthquake in Alaska, for instance, resulted in a 5m depth change and a lot of structural changes had to be made for Alaskan harbours.”
Tsunami waves can cause waters in certain coasts to be deeper and others shallower, he says. Harbours in shallow waters would have to be moved.
In a report in The Star yesterday, geologist Prof Ibrahim Komoo of Universiti Kebangsaan Malaysia said Sumatra would not have moved closer to Peninsular Malaysia because the peninsula and the Indonesian island are located on the same tectonic plate. If Sumatra moves, Peninsular Malaysia would also move, he said.
Dr Maged Mahmoud, a physical oceanographer from Kolej Universiti Sains dan Teknologi Malaysia (Kustem) in Terengganu, says the energy of the tsunami could cause changes at the bottom topography along the coastline of Penang.
“The tsunami wave spread from the north-west of Peninsular Malaysia, so the sediment transported was southward and along the western coastline of Malaysia. If there is high accumulation of sand along the coast especially on Penang island, this can affect the northward current movement in the Straits of Malacca,” he says.
This can affect navigation and reduce the speed of sea current, particularly in the onshore areas of Penang as a result of increasing topography friction, he says.
While seawater has moved further inland in Aceh, Maged does not think that this has happened in Malaysia. He says Malaysian mapping does not need revising.
Tide too does not change because it is influenced by the gravitational interaction between the Earth and the moon.
“Malaysia was lucky. If there were high tide and strong wind when the tsunami hit, it would have been a super wave or storm that could swallow up all the infrastructure along the coast of Penang,” he says.
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