There was a report on NOAA that our location in Hawaii detected it and sent warnings out too.
I have no idea where the communication break down occurred.
The breakdown occurred at multiple levels. The UN had no Tsunami education program in place in that region, for one thing (Kofi was too busy snow skiing on UN money). For another, the local governments didn't put up signs to educate their own people about the warning signals of an impending tsunami.
Failing the above, the local governments received the American tsunami warning but didn't tell their own people on the shores.
So the only people who were warned were those who heard the American alert from our in-place tsunami detection system, and those few who were told face-to-face by some wise elders (but even those elders bear some fault for not putting up warning signs at beaches years ago).
I think the question should be why, not where.
IT was Christmas Day, and Asia has no detection/sensor system like ours. There is not a formal system for getting a warning to an area that has no counterpart staff.
As I just explained on another thread, for most, there wasn't ANYTHING (warning, alarms, George Bush standing there and explaining what a tsunami force wave could do, etc.) that would have saved them. Entire villages and cities were wiped out. Small islands, everything is gone or covered with mud. Just where could these people have gone, had they been warned?