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NOAA image of tsunami buoy being deployed in the Pacific Ocean from the NOAA ship Ronald H. Brown.Dec. 29, 2004 � NOAA scientists at the Pacific Tsunami Warning Center in Hawaii went to work within minutes of getting a seismic signal that an earthquake occurred off the west coast of Northern Sumatra, Indonesia. NOAA issued a bulletin indicating no threat of a tsunami to Hawaii, the West Coast of North America or to other coasts in the Pacific Basin—the area served by the existing tsunami warning system established by the Pacific rim countries and operated by NOAA in Hawaii. (Click NOAA image for larger view of tsunami buoy being deployed in the Pacific Ocean from the NOAA ship Ronald H. Brown. Click here for high resolution version, which is a large file. Please credit “NOAA.”)

NOAA scientists then began an effort to notify countries about the possibility that a tsunami may have been triggered by the massive 9.0 undersea earthquake. The Pacific Basin tsunami warning system did not detect a tsunami in the Indian Ocean since there are no buoys in place there. Even without a way to detect whether a tsunami had formed in the Indian Ocean, NOAA officials tried to get the message out to other nations not a part of its Pacific warning system to alert them of the possibility of a tsunami. However, the tsunami raced across the ocean at speeds up to 500 mph. Below is the timeline of agency's actions once the undersea earthquake was detected by the NOAA Pacific Tsunami Warning Center in Hawaii.

NOAA Tsunami Warning Center: Timeline of events for the Dec. 25, 2004, Indian Ocean Tsunami. This version contains additional information—based on phone records, etc.—from the preliminary timeline posted Dec. 29, 2004. The items in brackets are awaiting further verification. Click here to view the preliminary timeline.

(updated Jan. 28, 2005)
2:59 p.m. The rupture of the great earthquake begins in the Indian Ocean off NW Sumatra, Indonesia.

3:07 p.m. Initial seismic signals from the earthquake trigger alarms at the NOAA Pacific Tsunami Warning Center (PTWC) in Hawaii.

3:10 p.m. PTWC issues a message to other observatories in the Pacific with preliminary earthquake parameters. Several geophysical observatories, including PTWC, initially under-estimated the size as around a magnitude 8.0.

3:14 p.m. PTWC issues a Tsunami Information Bulletin providing information on the earthquake and stating there is no tsunami threat to Pacific coasts. It is a text message distributed by multiple means to participants of the Tsunami Warning System in the Pacific. PTWC also advises the following offices by telephone as part of its standard operating procedure: 1) Hawaii Civil Defense, 2) Pacific Command (PACOM) of U.S. Military Forces, 3) U.S. Navy-Hawaii Region, and 4) International Tsunami Information Center.

[3:15 p.m.] Tsunami waves begin striking the coasts of northern Sumatra and the Nicobar Islands.

4:04 p.m. PTWC issues a second Tsunami Information Bulletin to the Pacific revising the earthquake magnitude to 8.5 based on later seismic energy. The bulletin again indicates no tsunami threat to the Pacific, but language is added to advise the possibility of a tsunami near the epicenter.

[4:30 p.m.] PTWC attempts to contact the Australian Bureau of Meteorology to verify they received the bulletin. As their main line was busy, they called Emergency Management Australia instead. EMA indicated Australia was aware of the earthquake.

[4:45 p.m.] Tsunami waves begin striking the coasts of Sri Lanka, India and Thailand.

6:21 p.m. A magnitude 7.1 aftershock occurs. PTWC staff evaluate the earthquake with some difficulty due to its signal being mixed with large seismic waves still active from the main event. No bulletin is issued for this event due to its much smaller size compared to the main shock.

[6:30 p.m.] Tsunami waves begin striking the Maldive Islands.

7:12 p.m. Reuters Internet wire service posts its first story indicating a tsunami has hit Sri Lanka causing 150 casualties. It also reports 100 tsunami injuries in Thailand.

7:25 p.m. The first data from the Australian National Tidal Center gauge at Cocos Island gives a reading of 0.5m crest-to-trough. This was the only sea level data in the Indian Ocean available to PTWC.

Also at 7:25 p.m. the Harvard University Seismology Department reports its preliminary Centroid Moment Tensor solution that indicates a magnitude of 8.9. (This was adjusted by Harvard the following day to 9.0.)

7:32 p.m. PTWC issues a message to the Tsunami Bulletin Board that goes by e-mail to international tsunami scientists and organizations. The message reports that based on the Reuters news wire article, a destructive tele-tsunami was generated by the Sumatra earthquake.

7:55 p.m. PTWC re-contacts the Australia Bureau of Meteorology and advises it of the increased earthquake magnitude and the 0.5 m reading at Cocos Island. They indicate that while they can't make any kind of forecast there is the possibility of destructive tsunami waves on Australia's western coasts.

[8:00 p.m.] PTWC re-contacts PACOM to advise of the increased earthquake magnitude and potential tsunami impacts in the western Indian Ocean.

[8:15 p.m.] The Australia Bureau of Meteorology calls PTWC to advise they have issued an alert to their western coasts.

[9:00 p.m.] PTWC receives a call from a Sri Lanka Navy Commander inquiring about the potential for further tsunami waves from aftershocks.

[9:15 p.m.] The U.S. Ambassador in Sri Lanka calls PTWC to set up a notification point in case of aftershocks with tsunamigenic potential.

[9:30 p.m.] The NOAA National Weather Service Pacific Region director reports to PTWC that PACOM has informed him they did not observe a destructive tsunami at Diego Garcia.

[10:00 p.m.] The U.S. State Department Operations Center calls PTWC and is advised of the potential threat to the western Indian Ocean and eastern Africa. They agree to set up a conference call with U.S. embassies in the region.

10:15 p.m. The U.S. State Department Operations Center sets up a conference call with the U.S. embassies at Madagascar and Mauritius. PTWC advises that based on the size of the earthquake and there being reports of tele-tsunami impacts in the Bay of Bengal, there is the potential threat of a damaging tsunami in the western Indian Ocean.

[10:15 p.m.] Tsunami waves have crossed Mauritius and are close to reaching Madagascar. They are also starting to impact the northernmost part of the east coast of Africa.

Dec. 26, 2004
5:36 a.m. PTWC issues a third tsunami information bulletin indicating small sea level fluctuations from the Indian Ocean tsunami are being observed in the Pacific Ocean, probably from tsunami energy that passed south of Australia.

The Pacific Warning System
Pacific warning network is comprised of (1) hundreds of seismic stations worldwide; (2) coastal tide gauges and sophisticated Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys in the Pacific Basin capable of detecting a centimeter's difference in ocean height.

However, it is important to note that without similar gauges and buoys in the Indian Ocean, PTWC officers were not in a position to detect a tsunami there.

NOAA's Responsibility to the International Community
The U.S. has demonstrated the effectiveness of its warning system within the Pacific region. It has also demonstrated that the warning system can provide initial earthquake information to other nations and is most willing to share that information with all concerned. With national dissemination and water level networks in place, NOAA's information can be used to mitigate future disasters.

It is also important to recognize that tsunamis can come ashore within minutes of nearby earthquakes. In those instances, people must know what to do in the event of a "felt" earthquake in low lying coastal areas.

The need for a tsunami warning program outside the Pacific region has been raised since 1985 with little result. It now appears that there is new interest in this issue within the international ICG/ITSU community. The U.S. strongly supports such an effort.

Furthermore, the development of the Global Earth Observing System of Systems (GEOSS) led by the United States, Japan, South Africa and the European Commission—with 53 nations currently participating at the ministerial level-should help fill the sensor gap for other regions of the world. Two key focus areas of the GEOSS initiative are addressing "reducing loss of life and property due to disasters" and "monitoring our oceans."

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nation�s coastal and marine resources. NOAA is part of the U.S. Department of Commerce.

Relevant Web Sites
NOAA Pacific Tsunami Warning Center Bulletins and Map

NOAA Tsunami Page

Deep-ocean Assessment and Reporting of Tsunamis (DART)

NOAA Water Level Observation Network

NOAA and Tsunamis

NOAA Tsunami Research Program

NOAA TsunamiReady Communities are Prepared

NOAA Tsunami Warning System Receives High Marks

NOAA Leading the Way in Tsunami Research and Education

Updated 1/28/2005

Media Contact:
Scott Smullen, NOAA, (202) 482-6090; Delores Clark in Honolulu, Hawaii, (808) 532-6411; Jana Goldman, NOAA Research, in Silver Spring, Md, (301) 713-2483; or Ann Thomason in Seattle, Wash., (206) 526-6800