National Tsunami Warning Center, NOAA/NWS

Tsunami of 21 October, 2011 (Kermadec Islands Region)

A Major earthquake with a moment magnitude of 7.4 (USGS magnitude) occurred at 17:57:16 UTC 21 October, 2011 (day 294) and was located 103 miles/166 km east of Raoul Island (Kermadec Islands: 28.998S, 176.183 W, 20.4mi/33km depth--USGS location).

This earthquake produced a tsunami that was recorded at tide gages operated by GNS Science in cooperation with the New Zealand Earthquake commission as well as at a DART buoy operated by the NOAA/NWS National Data Buoy Center (see the NDBC site for DART data).

Many observatories provide data to the tsunami warning centers; such as the NOAA National Ocean Service, the U. of Hawaii Sea Level Center, the Chilean Navy, and the National Tidal Facility in Australia among others. Click on the site name to see a graph of the tsunami, when available. Listed wave heights are maximum amplitude in cm (above sea level). Observed Arrival time is the actual tsunami arrival time in UTC on gages where it could be determined. The Computed Arrival time is the estimated time of arrival computed at the National Tsunami Warning Center (NTWC) based on the origin time and location. The Sample Interval column shows the time between samples.

For additional information about this tsunami event see the Pacific Tsunami Warning Center's homepage.


Travel Time Map
(click to enlarge)

Maximum Amplitude Graph
(click to enlarge)


Tide gage/
Measurement Location

Estimated Arrival Time
[UTC (J.Day)]

Observed Arrival time
[UTC (J.Day)]

Peak amplitude
(above sea level in cm)

Time of Peak Amplitude Measurement
[UTC (J.Day)]

Model Forecast Amplitude
(above sea level in cm)

Initial motion

Sample Interval

Data File
(Julian Day Starts
at 0000 UTC)

Raoul Island, Fishing Rock


1807 (294)


1819 (294)



294, 295

Raoul Island, Boat Cove

1818 (294)

1805 (294)


1810 (294)



294, 295

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