Two Indonesian tsunami warning buoys, put in place after a 2004 earthquake and tidal wave killed more than 230,000 people, failed to activate on Oct. 25 when a 7.7 magnitude temblor hit the country’s Mentawai Islands. This time, more than 400 died.
Even if the buoys had been operational, islanders would not have had enough time to evacuate, since the earthquake that triggered the tidal wave occurred too close to shore, according to the U.S. National Weather Service.
After the 2004 event, the U.S. National Oceanic and Atmospheric Administration donated two Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys to monitor Indonesian and Thai waters at a cost of $400,000 each. One stopped reporting in March of 2008 and was declared lost at sea. The other stopped reporting in June 2010 when it broke free from its moorings. It was recovered in July, but not reestablished.
“Operations and maintenance is the responsibility of the Indonesian government,” said Susan Buchanan, spokesperson for the National Weather Service.
The buoys are part of a warning system that starts with measurement of seismic activity at the ocean floor. Strategically deployed buoys use automatic detection and reporting algorithms triggered by a threshold wave-height value to report activity that could confirm the forecasts from the seismic monitors.
Data is transmitted by satellite and processed in real time in Alaska and Hawaii. The results determine when to issue watches, warnings or evaluations.
A September National Academy of Sciences report noted that, “ability to detect and forecast tsunamis has improved since the 2004 Indian Ocean tsunami, but current efforts are still not sufficient…for… tsunamis generated near land, which leave little time for warning.”