At 1748 UTC on September 29, a magnitude 8.3 earthquake occurred southwest of American Samoa, and a destructive basin-wide tsunami was generated. This event was confirmed at both coastal tide gauges and tsunameters (buoys) throughout the Pacific Basin. Due to the location of the earthquake, and the proximity to American Samoa, the NOAA tide gauge at Pago Pago was critical in confirming tsunami generation and developing initial arrival times for the Pacific and West Coast.

The Tsunami Warning Center measurement at Pago Pago was 1.57 m at 1812 UTC.


The tsunami reached Hawaii shortly after 0000 UTC on September 30, and was measured at a number of coastal tide stations. The highest observed wave height in Hawaii was measured at Kahului, Maui, with a height of 0.36 m at 0113 UTC.

Warnings were in effect for the West Coast from Oregon through Southern California. The tsunami reached the West Coast shortly before 0500 UTC on September 30, and was measured at a number of coastal tide stations. The highest observed wave height on the West Coast was measured at Arena Cove, California, with a height of 0.33 m at 0459 UTC. Due to the shape of several West Coast harbors and bays, the tsunami signal resonated for several hours in locations such as Crescent City, and advisories remained in effect for much of the morning due to wave and current activity.

The CO-OPS Tsunami Web Site, developed in collaboration with the NOAA Tsunami Warning Centers and the Pacific Marine Environmental Laboratory, provides a comprehensive source for 1-minute NOAA tide gauge data. Please click here for the CO-OPS Tsunami Web Page.

For more information, please contact Allison Allen, CO-OPS COASTAL Program Manager (Allison.Allen@noaa.gov) or go to:

• http://tidesandcurrents.noaa.gov/tsunami
• http://wcatwc.arh.noaa.gov/
• http://www.prh.noaa.gov/ptwc/
• http://www.ndbc.noaa.gov/dart.shtml
• http://www.cnn.com/2009/WORLD/asiapcf/09/30/samoa.earthquake/index.html

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