New Orleans marks Katrina victims and braces for Gustav

NEW ORLEANS (Reuters) - Residents of New Orleans paused on Friday to mark the third anniversary of Hurricane Katrina's devastating blow even as another potentially powerful storm churned their way.

City residents, many of whom are still recovering from the destruction of Katrina, now face the possibility of an evacuation order as early as Friday evening to escape the expected landfall next week of Tropical Storm Gustav.

Gustav, which killed at least 72 people in the Caribbean in mudslides and floods, could strengthen into the most powerful hurricane to hit the U.S. Gulf Coast since 2005.

Officials paused their Gustav preparations to hold an abbreviated ceremony to mark the third anniversary of Katrina with a symbolic burial service for more than 80 unidentified victims of the 2005 storm.

About 150 residents gathered in a cemetery and a lone trumpeter played a dirge as pallbearers guided a single silver casket from a horse-drawn carriage.

"We look forward to a better day, even as we prepare for a threat to come," said New Orleans Mayor Ray Nagin.

Bells rang through the city at 9:38 a.m., the time on August 29, 2005, when the city's levees began to give way. Federal officials say the levees are stronger but gaps still exist that leave some of the neighbourhoods hardest hit by the 2005 flooding vulnerable.

Katrina's waters flooded 80 percent of New Orleans, killed 1,500 people along the Gulf Coast and caused at least $80 billion in damages.

U.S. President George W. Bush, who was widely criticized for a slow federal response to Katrina, on Friday declared an emergency in Louisiana.

Nagin has warned residents that the trailers issued to them by the federal government as temporary housing after Katrina could turn into "missiles" in the grip of tropical storm-force winds and are not a good place to ride out Gustav. There are about 2,800 trailers in New Orleans.

POSSIBLE LANDFALL LOCATIONS

Gustav was predicted to strengthen over deep, warm Caribbean waters and plough ashore next week near New Orleans, according to the U.S. National Hurricane Centre.

Possible U.S. landfall locations stretched from the Florida Panhandle to Texas, and governors of Louisiana, Texas and Mississippi declared emergencies to allow them to call up troops and mobilize emergency efforts.

But the focus on Friday was squarely on New Orleans and its levees. The storm's current projected track takes it into the low-lying Terrebonne Parish southwest of New Orleans, one of the least-protected areas on the Louisiana coast.

Plaquemines and St. Bernard parishes could get pounded again, and the West Bank of Jefferson and Orleans parishes - largely spared in Katrina - could be at the greatest risk.

The low-lying Lafourche Parish will be under a mandatory evacuation order as of Saturday afternoon, local officials said.

The U.S. Army Corps of Engineers, charged with the levees' upkeep, has said storm defences are stronger but that gaps still exist.

"We're getting ready to test that and find out exactly how good the Corps of Engineers is," Nagin said after the ceremony.

(Editing by Chris Baltimore and Jackie Frank)