PADANG, Indonesia — Three powerful earthquakes jolted Indonesia in less than 24 hours, triggering tsunami alerts today and sending panicked residents fleeing to high ground. At least nine people were killed in the tremors.

The first two quakes in western Indonesia — magnitudes 8.4 and 7.8 — were followed by a 6.2-magnitude temblor in the east, according to the U.S. Geological Survey.

The largest spawned nearly 10-foot-high waves on Sumatra island Wednesday, and the other two today triggered tsunami alerts, Indonesia's meteorological agency said.

Indonesia, the world's largest archipelago, is prone to seismic upheaval due to its location on the so-called Pacific "Ring of Fire," an arc of volcanos and fault lines encircling the Pacific Basin.

In December 2004, a massive earthquake struck off Sumatra island and triggered a tsunami that killed more than 230,000 people in a dozen countries, including 160,000 people in Indonesia's westernmost province of Aceh.

A 43-year-old fisherman named Rukhlan said residents in Muara Maras were horrified Wednesday when they saw the ocean retreat and then fire back to shore.

"I heard people screaming and yelling tsunami ... tsunami!" he said, adding that the water flooded the village and damaged dozens of homes. "Then I ran to find my children, but they had already run to the hills."

Two other powerful tremors followed today in western and eastern Indonesia. The third quake, which had a preliminary magnitude of 6.2, struck off Sulawesi island — a different fault line.