By Gui Qing Koh
SINGAPORE (Reuters) - The U.S. Navy is surveying the Malacca Strait and coastal waters off Indonesia for signs that last month's devastating Indian Ocean tsunami altered the sea bed under the world's busiest shipping lane.
The USNS John McDonnell, a 208-ft specialist vessel, left Singapore on Jan.18 and was expected to complete its work by the middle of February in waters off Indonesia's Aceh province near the epicenter of the earthquake that triggered the tsunami, U.S. Navy officials said.
The mission comes after the respected Marshall Islands Asia-Pacific maritime authorities issued an advisory that said the earthquake and tsunami may have been powerful enough to alter sea depths near Southeast Asia's Malacca Strait.
Singapore media have published reports saying the tsunami may have reduced water depths in the Aceh sea bed by as much as 3,000 ft. But some experts say such a massive change may not be plausible but that the sea bed likely changed.
"When tsunamis travel into shallow waters, they may pile up between 10 to 20 meters (30 to 65 ft) of sediment but that won't account for a thousand-meter change," said David Higgitt, associate professor of geography at the National University of Singapore.
As part of its mission, the U.S. naval vessel will examine the ocean floor under the Malacca Strait, said U.S. Navy Lt. Patrick Starke, who is based in Thailand.
The narrow strait between Malaysia and Indonesia, with Singapore at its southern entrance, carries more than a quarter of world trade and almost all oil imports to Japan and China, and is one of Asia's most strategically important channels.
Since July, the Indonesian, Singapore and Malaysian navies have conducted coordinated patrols of the 500-mile waterway through which about 50,000 commercial vessels sail each year.
"The survey started between Jan. 19 and 20 and is expected to end in the middle of Feb.," said Commander Vince Giampaolo of the U.S. Naval Oceanographic Office.
SENSITIVE WATERS
The presence of foreign military in the Malacca Strait has traditionally been a touchy issue. The waters around the epicenter of the earthquake and tsunami, which fall within the Indonesian Exclusive Economic Zone, are another sensitive region.
Suggestions last year by the United States that its forces play a more active role in strait security sparked opposition from Malaysia and Indonesia, whose officials said they could take care of the matter. Singapore appeared more open to the idea.
Since the issue emerged, the littoral states have moved to increase activities, with the coordinated patrols a key step.
But local authorities say ships that ply the Malacca Strait have not reported any problems since the Dec. 26 tsunami that left as many as 290,000 dead or missing.
"We have not received complaints from ship owners or heard any navigation problems," said Captain K.K. Foong, assistant director of the Singapore Shipping Association.
Some shipping companies doubt they will be hampered by a shift in the sea bed. "The impact should be minimal because our biggest vessels have 14-meter (45 ft) draughts," said Captain Chan Soo Chee, regional director of Orient Overseas Container Line, referring to the part of the ship under water.