The catastrophic death toll in Asia caused by a massive tsunami might have been reduced had India and Sri Lanka been part of an international warning system designed to warn coastal communities about potentially deadly waves, scientists say.

Victims in India and Sri Lanka were among the more than 13,300 killed after being hit by walls of water triggered by a tremendous earthquake early Sunday off Sumatra.

The warning system is designed to alert nations that potentially destructive waves may hit their coastlines within three to 14 hours. Scientists said seismic networks recorded Sunday’s massive earthquake, but without wave sensors in the region, there was no way to determine the direction a tsunami would travel.

A single wave station south of the earthquake’s epicenter registered tsunami activity less than 2 feet high heading south toward Australia, researchers said.

The waves also struck resort beaches on the west coast of the Thailand’s south peninsula, killing hundreds. Although Thailand belongs to the international tsunami warning network, its west coast does not have the system’s wave sensors mounted on ocean buoys.

The northern tip of the earthquake fault is located near the Andaman Islands, and tsunamis appear to have rushed eastward toward the Thai resort of Phuket on Sunday morning when the community was just stirring.

“They had no tidal gauges, and they had no warning,” said Waverly Person, a geophysicist at the National Earthquake Information Center in Golden, Colo., which monitors seismic activity worldwide. “There are no buoys in the Indian Ocean, and that’s where this tsunami occurred.”

Tsunamis as large and destructive as Sunday’s typically happen only a few times in a century.

A tsunami is not a single wave, but a series of traveling ocean waves generated by geological disturbances near or below the ocean floor. With nothing to stop them, these waves can race across the ocean like the crack of a bullwhip, gaining momentum over thousands of miles.

Parents grieve near the body of their child washed ashore at Silver Beach in Cuddalore, in the southern Indian state of Tamil Nadu. Massive tidal waves triggered by an Indonesian earthquake slammed into southern India on Sunday, killing at least 2,300 people.

Most are triggered by large earthquakes but they can be caused by landslides, volcanoes and even meteor impacts.

The waves are generated when geologic forces displace sea water in the ocean basin. The bigger the earthquake, the more the Earth’s crust shifts and the more seawater begins to move.

Tsunamis are distinguished from normal coastal surf by their great length and speed. A single wave in a tsunami series might be 100 miles long and race across the ocean at 600 mph. When it approaches a coastline, the wave slows dramatically, but it also rises to great heights because the enormous volume of water piles up in shallow coastal bays.