Although National Oceanic and Atmospheric Administration (NOAA) scientists at the Pacific Tsunami Warning Center (PTWC) in Hawaii eventually issued warnings of a possible tsunami from the large earthquake off Sumatra, the waves outran notification systems at jet speeds of 500 mph (804 km/h), catching hundreds of thousands of people unaware.
Resulting seismic signals received at the NOAA Pacific Tsunami Warning Center (PTWC) from stations in Australia who triggered an alarm that alerted bystanders.
These member nations are part of UNESCO's Intergovernmental Oceanographic Commission (IOC) and the International Coordination Group (ICG) for the ITSU.
The PTWC contacted the Australian Bureau of Meteorology and advised them about the increased earthquake magnitude and the 0.5m reading at Cocos Island, as well as the possibility of a destructive tsunami impact on Australia's west coasts.
The NOAA's National Weather Service Pacific Region director contacted the PTWC to report PACOM said no tsunami was observed at Diego Garcia in the Indian Ocean.