Tsunami Redraws Indian Ocean Maps

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The National Geospatial-Intelligence Agency (NGA) is also using its satellite technology to determine which areas around the Indian Ocean are heavily damaged and most in need of assistance. NGA's maritime navigation watch is collecting on-site reports from the Indian Ocean region. Both sources describe an area that no longer matches existing maps and charts.

"In this case we see massive erosion of the islands," said Chris Andreasen, chief hydrographer at NGA's Office of Global Navigation in Bethesda, Maryland. "That sediment had to go somewhere, so I'd expect shoaling in channels and areas where vessels typically try to navigate. We have no idea what that impact is right now."

NGA is producing satellite maps and other products that indicate damaged areas and serve as crucial aids to mariners in the treacherous waters.

"Two major lighthouses are out at the north end of the Strait of Malacca," Andreasen said. "You might think [mariners] could rely on GPS instead, but it turns out that one of [the lighthouses] was also the location of [a now broken GPS transmitter] as well. You don't expect that a lighthouse would be in a location that's going to be taken out."

Along the coastlines and near ports, wrecks and debris fill the waters. Buoys and other fixed navigational aids have been wiped out.

Local authorities in charge of maintaining such operations were not spared the impact of the wave. "I think that Sri Lanka had only one [survey] vessel, and it was destroyed, and their hydrographic office was also hit by the wave," Andreasen said. "I believe that one member of their staff was killed, so they are still shoveling mud out of that office."

Ports and Approaches Are a Treacherous Maze

Help is on the way as part of the international response to the tsunami. The primary goal is to open ports to vessels capable of carrying the enormous amounts of relief supplies headed into the region.

The U.S. Navy coastal survey vessel John McDonnell is expected to arrive in the Strait of Malacca on January 14. The ship carries two small hydrographic survey launches, equipped with high-frequency sonar to operate in depths of 10 to 260 feet (3 to 80 meters).

"We don't know the shape that the channels, approaches, and harbors are in, based on debris," said Capt. Jeffrey S. Best, commanding officer of the Naval Oceanographic Office (NAVOCEANO) at Stennis Space Center, Mississippi. "There could be buildings, cars, or all kinds of things blocking those approaches. Our guys need to make sure that it's safe so that we can get the big relief ships in there."

"We just want to produce a field chart that identifies major hazards to navigation," Best continued. "Our goal is not to survey to standard. We may be asked later for an in-depth survey."

Experts say it could take several months or more to open affected Indian Ocean ports. In the shorter term, some NAVOCEANO staff are using NGA satellite images to identify sandy beaches where supplies might be brought ashore by landing craft.

On arrival, the John McDonnell will also attempt to verify reports of dangerous shoals in the Strait of Malacca—among the world's busiest shipping areas.

Unverified reports suggest that areas of the straights that were once thousands of feet deep are now as shallow as 100 feet (30 meters)—too shallow for large commercial vessels.

While identifying target relief areas and charting safe courses for supply ships are top priorities, recreating the maps altered by nature's power will be a very long-term project.

"It's going to take years if not decades to survey the whole region, because [the impact] is just huge," NGA's Andreasen said. "We've never seen anything like this before."

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