PADANG, Indonesia - A second powerful earthquake in as many days shook western Indonesia today, collapsing buildings in a coastal city and triggering tsunami alerts around the region.
The latest quake was also felt in Malaysia and in Singapore, where tall buildings swayed. It triggered at least one strong aftershock.
A day earlier, a strong earthquake shook Southeast Asia, collapsing buildings, killing at least five people and injuring dozens in Indonesia. That tremor triggered a small non-destructive tsunami off the coastal city of Padang on Sumatra, the Indonesian island ravaged by the 2004 tsunami disaster. A tsunami warning was issued for wide areas of the region and nations as far away as Africa.
Today's magnitude-7.8 quake rattled the same area of Sumatra. Rafael Abreu, a geologist with the US Geological Survey in Colorado, said the quake did not appear to be an aftershock to the 8.4-magnitude temblor the day before. But the centers of both were close to one another.
"We are not calling it an aftershock at this point. It's fairly large itself. It seems to be a different earthquake," Abreu said.
"The quake seems to be pretty shallow," he said. "These are the quakes that can produce tsunamis."
Indonesia issued a tsunami warning, lifted it and then reissued it. Australia's Bureau of Meteorology issued a warning that unusual waves could hit Christmas Island, but locals said there was no sign of a tsunami about an hour after the predicted time.
"The danger has passed," said Linda Cash, a manager at the Christmas Island Visitors Center. The USGS said the new quake was centered about 125 miles from Bengkulu, a city on Sumatra. It occurred at a shallow depth of about six miles and struck at 6:49 a.m.
The Pacific Tsunami Warning Center in Hawaii warned that today's quake had the potential to generate a destructive regional tsunami along coasts within 600 miles of the epicenter. It advised authorities to take immediate action to evacuate coastal areas.
Today's quake caused extensive damage in Padang, a local official said.
"Many buildings collapsed after this morning's quake," Fauzi Bahar, the mayor, told El Shinta radio. "We're still trying to find out about victims."
Thousands of frightened people piled in trucks or sought shelter on high ground.
After Wednesday's quake, people fled their homes and ran inland, fearing a repeat of the 2004 earthquake and tsunami that struck a dozen nations around the Indian Ocean. That disaster killed an estimated 230,000 people in a dozen nations.
"Everyone is running out of their houses in every direction," Wati Said reported by cell phone from Bengkulu, a town 80 miles from the quake's epicenter. "We think our neighborhood is high enough. God willing, if the water comes, it will not touch us here."
One witness, Budi Darmawan, said a three-story building near his office fell.
This first quake was felt in at least four countries, with tall buildings swaying in cities up to 1,200 miles away.
It was followed by a series of strong aftershocks, further rattling residents.
Telephone lines and electricity were disrupted across a large swath of Indonesia, making it difficult to get information about damage and casualties.
Suhardjono, a senior official with the local meteorological agency who like most Indonesians uses only one name, said a small tsunami, perhaps 3-feet high, struck Padang about 20 minutes after the quake. The Pacific Tsunami Warning Center also reported a small wave.
But most of the damage appeared to come from the ground shaking.
In Indonesia's capital, Jakarta, hundreds of miles from the epicenter, office workers streamed down stairwells as buildings swayed. High-rises also were affected in Malaysia, Singapore, and Thailand.
Indonesia, the world's largest archipelago, is prone to seismic upheaval due to its location on the "Ring of Fire," an arc of volcanos and fault lines across the Pacific Basin.