Two intense earthquakes off the cost of Indonesiaset up back-to-back Tsunami Warnings; panickedresidents flooded the streets trying to escape tohigher ground. The tsunami watch for the regionwas lifted within a few hours after no deadlywaves or damage were reported.
Women and children cried in Aceh, where memoriesare still raw of a 2004 tsunami that killed170,000 people in the province alone. Othersscreamed "God is great" as they poured from theirhomes or searched frantically for separated familymembers.
Patients were wheeled out of hospitals, some stilllying in their beds with drips attached to theirarms. And at least one hotel guest was slightlyinjured when he jumped out of his window.
The U.S. Geological Survey said the first 8.6-magnitude quake was a shallow 22 kilometers (14miles), hitting in the sea 270 miles (435kilometers) from Aceh's provincial capital.
An alert that followed from the Pacific TsunamiWarning Center in Hawaii advised countries allalong the rim of the Indian Ocean, from Australiaand India to as far off as Africa, that aseismically charged wave could head their way.
Two deadly tsunamis in the last decade -- the mostrecent off Japan just one year ago -- have left theworld much better prepared.
Sirens sounded along coastlines and warningsspread like wildfire by mobile phone textmessaging. Though often chaotic, evacuations beganimmediately with streets clogged with traffic,especially in Aceh.
The only wave to hit, though, was less than 30inches (80 centimeters) high, rolling toIndonesia's emptied coastline.
Just as the region was sighing relief, an 8.2-magnitude aftershock followed.
"We just issued another tsunami warning," PrihHarjadi, from Indonesia's geophysics agency, toldTVOne in a live interview.
He told his countrymen to stay clear of westerncoasts.
Residents in Aceh could hardly believe it.
"What did we do to deserve this?" cried AisyahHusaini, 47, who lost both her parents and a sonin the 2004 tsunami. "What sins have wecommitted?"
"I'm so scared, I don't want to lose my familyagain," she said, clinging to her two children ina mosque in Banda Aceh, where hundreds of peoplesheltered.
Again, though, the threat quickly passed.
Experts said Wednesday's quakes did not have thepotential to create massive tsunamis because thefriction and shaking occurred horizontally, notvertically. The earth's tectonic plates slidagainst each other, creating more of a vibrationin the water.
In contrast, mega-thrust quakes cause the seabedto rise or drop vertically, displacing massiveamounts of water and sending towering waves racingacross the ocean at jetliner speeds.
Roger Musson, seismologist at the Britishgeological survey who has studied Sumatra's faultlines, said initially he'd been "fearing theworst."
"But as soon as I discovered what type ofearthquake it was ... I felt a lot better."
The tremors were felt in neighboring Malaysia,where high-rise buildings shook, and Thailand,India and Bangladesh.
Those countries, Sri Lanka and the Maldivesevacuated buildings and beaches and readied reliefefforts in case of disaster.
The World Meteorological Organization saidcommunication systems set up after the 2004tsunami appeared to have worked well.
"Our records indicate that all the nationalmeteorological services in the countries at riskby this tsunami have received the warnings inunder five minutes," said Maryam Golnaraghi, thehead of WMO's disaster risk reduction program.
The alert was sent out by U.S. National WeatherService, which operates a tsunami warning stationin Hawaii, she said.
Indonesia straddles a series of fault lines thatmakes the vast island nation prone to volcanic andseismic activity.
The giant 9.1-magnitude quake and tsunami on Dec.26, 2004, killed 230,000 people in about a dozennations.