CORRECTED: Sudden sea level surges threaten 1 billion

(Corrects paragraph 3 to above from below sea level)

By Michael Kahn

SAN FRANCISCO (Reuters) - More than 1 billion people live in low-lying areas where a sudden surge in sea level could prove as disastrous as the 2004 Asian tsunami, according to new research presented on Thursday.

New mapping techniques show how much land would be lost and how many people affected by rapid sea level rises that are often triggered by storms and earthquakes, a U.S. Geological Survey-led team determined.

E. Lynn Usery, who led the team, said nearly one-quarter of the world's population lives below 100 feet above sea level -- the size of the biggest surge during the 2004 tsunami that pulverized villages along the Indian Ocean and killed 230,000 people.

"What we are suggesting is what kind of areas are at risk (in) a catastrophic event," Usery told a meeting of the Association of American Geographers.

"The fact that there are that many people living at that sea level means there are probably a lot of people potentially in harm's way."

The team also found that a 100-foot (30-meter) rise in sea level would cover 3.7 million square miles of land worldwide.

A rise of just 16 feet would affect 669 million people and 2 million square miles of land would be lost.