How the Indian Ocean gets tsunami warnings|tsunami

For more than 40 years, the Pacific Tsunami Warning Center (PTWC) has been alerting countries in the Pacific region to the dangers of killer waves.

Following the 2004 Indian Ocean tsunami that killed almost 230,000 people, the United Nation's Intergovernmental Oceanographic Commission (IOC) began coordinating efforts to create an Indian Ocean tsunami early warning system.

Before 2004, there were no sea-level monitoring instruments in the Indian Ocean and many countries did not have agencies responsible for tsunami warnings or points of contact to receive messages from international warning centers.

Five years on, a vast network of seismographic centers, national warning centers or agencies, coastal and deep-ocean stations is in place across the Indian Ocean to detect potential tsunamis and pass on warnings to communities.

Here's how the system works:

WARNING CENTRES

When an earthquake strikes in the Indian Ocean region, data from a variety of sources is transmitted to the Pacific Tsunami Warning Center (PTWC) based in Hawaii and the Japan Meteorological Agency (JMA) in Tokyo.

The two centers currently have responsibility for providing the Indian Ocean with what are known as tsunami "watches."