A massive earthquake that hit Indonesian waters in the Indian Ocean Wednesday afternoon tested and highlighted the responsiveness of tsunami preparedness of countries in the region, UN officials said Thursday.

5 killed, 4 injured after quakes hit Indonesia

At least eight countries issued tsunami alerts following the 8. 6-magnitude earthquake that struck 437 km off the coast of Sumatra, Indonesia at 3:38 p.m. Evacuation orders were issued immediately for coastal areas in Indonesia, followed by Thailand, Sri Lanka, India and Myanmar. Two hours later an 8.2 aftershock triggered a second wave of tsunami warnings across the region.

"The fact that most people in the affected areas were promptly alerted to the situation and moved to higher ground is a testament to the effectiveness of the preparedness actions and early warning system," said Ignacio Leon-Garcia, head of the United Nations Office for the Coordination of Humanitarian Affairs (OCHA) in Indonesia.

"It is clear that the investment by Governments and partners on disaster preparedness is bearing fruit and is the best way to address the region's disaster management challenges. This lesson learned should encourage us all to increase our investment in disaster preparedness and management activities," said Oliver Lacey-Hall from the OCHA Asia Pacific regional office.

Indian Ocean countries, including Indonesia, Thailand, India and Sri Lanka have invested heavily in disaster response capacity and early warning systems after a tsunami, triggered by a 9.1- magnitude quake, killed more than 226,000 people in the region in 2004, an OCHA statement said.

No major tsunami nor significant damage were reported from Wednesday's earthquake. But warning systems were praised for their effectiveness, especially the use of mobile phones which promptly alerted people to the risk so they could move to higher ground, the statement said.

"It is during such moments that the effectiveness of our work on preparedness and early warning can be assessed. Based on this instance, I think we can be reassured that we are on the right track," said Ignacio Leon-Garcia.

National search and rescue agencies and disaster response teams from ASEAN and UN were on standby across the region and were closely monitoring the situation and exchanging information, the statement added.

VietNamNet/Xinhuanet