see:

Bush’s response to South Asia disaster: indifference compounded by political incompetence
By Patrick Martin
30 December 2004
 http://www.wsws.org/articles/2004/dec2004/bush-d30.shtml

excerpt:

There is already evidence that the US government had ample warning of the earthquake-driven tsunami, but did not communicate the information to the countries involved. US press reports indicate that the Pacific Warning Center in Hawaii, a facility of the National Oceanic and Atmospheric Administration, detected the earthquake when it occurred and immediately warned of the likelihood of tidal waves generated by one of largest temblors ever recorded.

Charles McCreery, director of the center, confirmed that his team had transmitted warnings to the US Navy, the US State Department and the government of Australia. The State Department claimed to have notified India, but the Indian government said it received no such warning in the two hours that elapsed between the quake off Sumatra and the tidal wave that hit the Indian coastline in the southern province of Tamil Nadu. Nor did the Sri Lankan government receive a warning.

But one Indian Ocean island was promptly warned—the US military base on the British-controlled island of Diego Garcia, the site from which US bombing raids have been staged on both Afghanistan and Iraq. The US base, about 1,000 miles south of India, directly in the path of the tsunami, reportedly suffered no damage.