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Residents surveying damage from two powerful earthquakes that reignited memories of the devastating 2004 Indian Ocean tsunami said Thursday they could hardly believe their luck.

Five people died from heart attacks, and a few others were injured as mobs used cars and motorcycles to flee to high ground in Indonesia's westernmost province of Aceh -- closest to the epicenters.

But aside from cracks in the walls of houses and structural damage to one bridge, you would hardly know anything happened, said Usman Basyah, smiling as he handed change to customers at his small street stall.

"I really feel my prayers were answered this time," said Basyah, who lost one of his sons in the disaster eight years ago. "I'm so grateful. We've gone through enough trauma already."

Another man, who spent the night in a mosque sheltering hundreds of others who were worried about the regular aftershocks, agreed.

"Of course, I was scared," said Nasir Djamil. "We all were. But were much better prepared this time. I think we learned from the last nightmare. We knew what we had to do.

That was the sentiment across much of the globe.

The first quake, measuring 8.6, triggered a tsunami watch around the Indian Ocean, from Australia and India to as far off as Africa. Hours later, a powerful 8.2-magnitude aftershock hit.

Warning buoys -- put in place after the 2004 disaster that killed 230,000 people in a dozen nations, three quarters of them in Aceh -- accurately predicted that the tsunami would not be big.

Sirens sounded along coasts and warnings spread like wildfire by mobile phone text messaging.

And, for the most part, evacuations appeared to go smoothly.

Still, traffic-clogged streets in Aceh pointed to the need for better organization.

Twenty minutes after the quake hit, cars and motorcycles were at a standstill in areas that, in 2004, were inundated with water, sweeping tens of thousands to their deaths.

"It wouldn't have been as bad," said Iskandar, a local disaster management official. "But I dare to say, if there had a been a repeat, there would have been deaths."

The real luck came with the type of quake that hit.

Indonesia, a sprawling archipelagic nation of 240 million people, straddles a series of fault lines that makes it one of the most seismically active places on the planet.

Aceh, which sits off a subduction zone fault, were one tectonic plate of the Earth's crust dives under another, has experienced numerous "mega thrust" quakes over time.

It's these temblors that cause the seabed to rise or drop vertically, displacing massive amounts of water that race across the ocean at jetliner speeds.

But experts say Wednesday's twin tremors occurred on what is known as a "strike-slip" fault.

The sea floor shifted horizontally, creating more of a vibration in the water.

As result, the only wave generated was less than 80 centimeters (30 inches) high. It washed ashore on deserted beaches nearest the epicenter.

Like so many people, Rahmi Novianti, a 25-year-old housewife, had been fearing the worst.

"I was running out of my house, I could see the tsunami coming in my mind, the entire village again being destroyed," she said. "That it didn't happen really feels like a blessing."

Though the shaking on land was fierce, lasting nearly four minutes and triggering mass panic, only five people died, Asmadi Syam, head of Aceh's disaster management agency, told MetroTV.

He said all were from heart attacks, presumably triggered by the panic.

At least four other people were injured.