Indian Ocean tsunami early warning system was designed to combine data from underwater probes, orbiting global positioning system satellites, and floating buoys, to better detect a coming tidal wave.
By David Singh
GENEVA, 11 April 2012 - Following a massive earthquake earlier today in the Indian Ocean and the threat of a tsunami, Indonesian President and UNISDR Global Disaster Risk Reduction Champion, Susilo Bambang Yudhyono, told the press, "Our early warning system is working well". There were no tsunamis in Banda Aceh or other places which were hard hit by the 2004 Indian Ocean tsunami.
The 8.6 magnitude earthquake occurred at 8.38 UTC, 437 km southwest of Banda Aceh in Indonesia and 33 km beneath the ocean floor, prompting a tsunami watch to be immediately issued for Australia, Bangladesh, Comoros, Crozet Islands, Diego Garcia, India, Indonesia, Iran, Kenya, Kerguelen Islands, Madagascar, Malaysia, Maldives, Mauritius, Mozambique, Myanmar, Oman, Pakistan, Reunion, Seychelles, Singapore, Sri Lanka, Somalia, South Africa, Tanzania, Thailand, United Arab Emirates and Yemen.
Despite initial panic by people in many at-risk locations when they thought they would experience a repeat of the devastating 2004 Indian Ocean Tsunami which swept through many of the same areas on tsunami watch today, early warning systems and evacuation drills today appear to have demonstrated their usefulness.
"This quake released less energy than the 9.1 magnitude 2004 earthquake which was roughly in the same location", observed Jerry Velasquez, Head of the UNISDR Asia-Pacific Office.
"The destruction in 2004 was linked to the tsunami generated by the shifting of tectonic plates. There are many variations of tectonic shifting that cause earthquakes. Some plates are displaced vertically, while others are displaced horizontally. In general, the vertical displacement of plates is more likely to generate tsunamis. Fortunately this quake was caused by tectonic plates that shifted horizontally," said Velasquez.
Confirming that people in Banda Aceh were able to evacuate to safe areas, President Yudhoyono told reporters, "There are no casualties or major damage reported, but we remain vigilant. I have ordered the national relief team to fly immediately to Aceh to ensure the situation is under control and to take any necessary action."
According to Thorkild Aarup, Head of the Tsunami Unit of the UN Intergovernmental Oceanographic Commission (IOC), "The three early warning systems functioned as they should have across the board. The Indonesian early warning was issued at 8.43 UTC - five minutes after the quake happened. The Australian warning was issued 10 minutes after, while India's was issued eight minutes after the earthquake."
In the aftermath of the 2004 the IOC (comprising UNESCO and other partners) began coordinating efforts to create an Indian Ocean tsunami early warning system. An interim system was established in 2005 which culminated with the establishment of the three early warning providers this year -- Australia, India and Indonesia.
Today there is a large network of seismographic centres, national warning centres, agencies, coastal and deep-ocean stations in place across the Indian Ocean to detect potential tsunamis and pass on warnings to communities.
Gaps remain in the system - most significantly at the community level - and experts say more coordination is needed to ensure national centres are communicating with each other and sharing information across the region.
"Yes there are gaps," said Aaarup, "But the Indian Ocean is much better prepared than it was in 2004. The tsunami early warning systems are like the atmospheric systems used by meteorologists which are constantly being improved by new technology. The same is true for the tsunami warning systems".
According to news reports tsunami warning sirens were heard in Phuket where people were observed to be calmly following evacuation routes to safe zones. Authorities shut down the international airport, hotel guests in the resort area were evacuated to the hills behind while local people were seen heading for higher ground in cars and on motorcycles.
People near the coast in six Thai provinces were ordered to move to higher ground. In the city of Medan, a hospital evacuated patients, who were wheeled out on beds and in wheelchairs. In southern India, hundreds of office workers in the city of Bangalore left their buildings while the port of Chennai closed down because of tsunami fears.
Al Jazeera's meteorologist Kevin Corriveau explains the earthquake and tsunami