The undersea earthquake that struck 160 kilometers (100 mi) west of Sumatra in December 2004 was more powerful than all of the world's earthquakes over the last five years combined. The magnitude 9.0 to 9.3 event, which shifted the entire planet, spawned a tsunami that killed as many as 300,000 people and displaced more than 1.5 million people living near the Indian Ocean.
Many of those who were killed, especially in places far from the earthquake's epicenter, might have been saved if a comprehensive tsunami warning system had been operating in the Indian Ocean. With 600 million or more people across the globe predicted to be living within 100 kilometers (62 mi) of coastlines by 2025, setting up effective tsunami warning systems in all the world's oceans is a critical task. Still, there are challenges, including technological limitations, fiscal constraints, and the bureaucratic red tape that hinders international cooperation and communication.
A warning system comprised of a seismic detection system, a tide gauge system, and a communications system has been in place in the Pacific Ocean since 1948, and it provides a model for an Indian Ocean system. The Pacific system has accurately detected every major tsunami since its installation. New sea-floor sensors, designed to monitor pressure changes in the water above them, were installed in 2002 to help reduce the high false-alarm rate (75 percent). The cost of implementing a system with similar instrumentation in the Indian Ocean would be between US$250 million and US$400 million.