By Chris Hogg
BBC News, Singapore
When the earth shook around the Indian Ocean in the darkest hours of Monday night, you can just imagine what went through people's minds.
Many people moved fast to get to higher ground
It was just over three months to the day since the tsunami had wrought havoc throughout this region.
Could it really be happening again?
The lack of a comprehensive early-warning system did not matter.
People knew how bad it could get - and they knew what they had to do.
For a few anxious hours the roads from the fishing villages and the beach resorts were clogged as people fled to higher ground.
Rapid response plans put in place after the 26 December disaster had to be used much sooner than had been expected.
An integrated tsunami warning system for the region will not be ready until the end of next year, but most countries had a contingency plan.
Almost everywhere the response appears to have been relatively quick and relatively co-ordinated.
A warning was passed from the Pacific Tsunami Warning Centre in Hawaii.
Officials were quick to spread to the word in Indonesia, India, Sri Lanka, Thailand and beyond.
On the ground they used megaphones, telephones, radio and television broadcasts to warn people to leave their homes.
But people needed little encouragement to seek a place of safety.
And that is what has changed in Asia as a result of the devastating tsunami at the end of last year.
No one in the worst affected areas needs persuading of the potential danger from the sea.
Those on the island of Sumatra and nearby have suffered regular aftershocks for the last three months.
'Better safe than sorry'
But even further afield, in Thailand, many of the fishermen or sea-gypsies I speak to are too frightened to take to sea, or to travel too far from the land.
Monday night's tremor will have confirmed their worst fears.
Some in the tsunami-hit region now fear the sea
In Indonesia, the focus is on rescue and relief on the islands which appear worst hit.
But elsewhere, officials will be examining their plans to see what worked and what was lacking.
In most areas the warnings were withdrawn before dawn, allowing people to get back to normal as quickly as possible.
On the Thai island of Phuket, holidaymakers were back on the beach by mid-morning on Tuesday.
The Indonesian town of Banda Aceh had resumed normal life within hours, although it is still recovering from the devastation of December's disaster.
The United Nations says the region still needs a reliable early warning system.
But until that can be put in place, the mood across the region appears to be "better safe than sorry".