Within minutes of the temblors off Indonesia's western coast on Wednesday - and yet another on Thursday - officials sent out warnings by mobile phone SMS, e-mail and fax to coastal communities in the path of potential monster waves.
Similar warnings reached governments as far away as Kenya, where coastal residents and tourists were ushered off beaches with megaphones and onto higher ground.
"They were quite fast in delivering the warning. The first warning went out in five or six minutes," said Michael Rottmann, the U.N. special coordinator for the early warning system in Indonesia. "The president announced the system will be ready in 2008, but this earthquake showed it's working already."
Officials acknowledged there were glitches, with evacuations in Indonesia marked by fear and panic in some hard-hit neighborhoods. Residents on Thailand's six southern provinces rushed to the hills and remained there for two hours - even though a tsunami alert had yet to be issued.
The 2004 tsunami hit southern Thailand, including the tourist resort of Phuket, and killed more than 8,000 people.
"People in the southern provinces heard warnings from other centers abroad and were panicking," Smith Dharmasaroja, director of the National Disaster Warning Center, told Thai TV viewers when he broke into regular programming to make an emergency address.
"If such incidents happen again in the future, please be confident and solely listen to warnings from the National Disaster Warning Center in Thailand so that it won't cause you panic and you don't have to run up to high grounds unnecessarily."
For some experts, the performance highlighted progress many governments in the region have made since the 2004 Indian Ocean disaster which left 230,000 dead. That disaster was marked by failure to warn many communities about the impending waves, mostly due to faulty equipment, poor communications and cumbersome bureaucracy.
It prompted the United Nations and six government donors, including the United States, to create a US$130 million (EUR97 million) tsunami warning system, which is expected to be fully operational at the end next year.
Progress was initially slowed by bickering over technical problems with deep-sea monitoring buoys. Governments also came under fire for failing to educate citizens about the threat of tsunamis, bolster coastal infrastructure, and establishing ways to pass along warnings to remote villages.
But in recent years, Indonesia, which was hit hardest by the 2004 disaster, has installed dozens of tidal gauges and deep-ocean tsunami monitoring buoys to detect waves as well as more than 150 seismometers to detect earthquakes.
It also has vastly improved its communication network, officials said, resulting in a quake alert going out within minutes of the actual temblor. The quake was detected on a seismograph which relays a message to the country's Meteorological and Geophysics Agency. It then sent a warning message to hundreds of emergency management personnel in the disaster-hit regions.
Much of East African coast was also under a tsunami watch on Wednesday, with Kenyan and Tanzanian television and radio urging residents to evacuate beaches following the earthquakes off of Indonesia.