India's tsunami warning plan still not accurate enough

On the eve of the 10th anniversary of the Indian Ocean tsunami, scientists plan to further improve the country's tsunami warming system by adding 35 new GPS stations to the network and installing more ocean sensors near the Pakistan coast.

The modifications, to be carried out in the next 18 months, will help the Indian warning system function more accurately in case of an earthquake of 9-magnitude or more—something similar to the Tohuku earthquake that led to the 2011 Fukushima disaster.

“At the moment, our system slightly underestimates big earthquakes. For better accuracy, we need data on the rupture, which can be obtained through these GPS stations, to be located in the Andaman and Nicobar islands,” Ministry of Earth Sciences secretary Shailesh Nayak told Deccan Herald.

For instance, the 9.0-magnitude Japan earthquake was recorded first as 7.9 and subsequently 8.5 by the Indian system in the absence of the rupture data.

As former director of the Indian National Centre for Ocean Information Services, Hyderabad, Nayak spearheaded the effort to set up the Indian warning system in the wake of the devastating December 26, 2004, tsunami that killed more than 2 lakh people and rendered many more homeless.

A tsunami warning system monitors the occurrence of any tsunamigenic earthquakes in the sea, and can predict the tsunami's arrival at the coast. The time between the earthquake and the tsunami's arrival depends on the distance from the source to the coast, which may vary from a couple of minutes at the Andaman-Sumatra islands to a few hours at the east coast of India.

“We can give alerts within 6-8 minutes in case of earthquakes in the Sumatra coast in the east and the Makran coast in the west. We plan to add another ocean data sensor in the Arabian Sea to reduce the redundancy in the tsunami alert system in case of quakes off the Pakistan coast,” said Nayak.

India, Indonesia and Australia perform the dual role of a national tsunami warning centre and a regional centre to timely warn 28 states around the Indian Ocean in the event of a threatening tsunami.

Besides India's own ocean data sensors, the Indian tsunami warning system receives information from data buoys employed by the Australian and Indonesian systems.