Magnitude 7.0 - KERMADEC ISLANDS, NEW ZEALAND

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Earthquake Details

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Earthquake Summary

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Tectonic Summary

The September 29, 2008, M7.0 earthquake occurred in the Tonga - Kermadec subduction zone. The subduction zone extends north-northeast from the North Island of New Zealand for over 2500 km through Tonga to within 100 km of Western Samoa. At a broad scale, tectonics of the subduction zone reflect the motion of the Pacific plate westward with respect to the interior of the Australia plate at a velocity of about 60 mm/y in the epicentral region of the earthquake. The Pacific plate subducts beneath the Australia plate at the Tonga and Kermadec trenches, and dips to the west. In detail, the eastern edge of the broad Australia plate may itself be viewed as a collection of small plates or microplates that move with respect to each other and with respect to the Pacific plate and the Australia plate interior. The location and focal-mechanism of the earthquake are consistent with it occurring as thrust faulting on the interface between the subducting Pacific plate and the overriding Australia plate (in detail, the overriding Kermadec microplate).

The interaction between the Pacific and Australia plate creates one of the most active tectonic environments in the world, with a high level of associated earthquake activity. Since 1976, a 200-km long section of the Tonga - Kermadec subduction zone that includes the epicenter of the September 29 earthquake has produced over 50 earthquakes of magnitude 6 or larger, with the largest having magnitude 7.9.

Tsunami Information

• NOAA West Coast & Alaska Tsunami Warning Center
• NOAA Pacific Tsunami Warning Center

The earthquake locations and magnitudes cited in these NOAA tsunami bulletins are very preliminary and may be superceded by USGS locations and magnitudes computed using more extensive data sets.

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Scientific & Technical Information

• USGS Centroid Moment Tensor Solution
• Global CMT Project Moment Tensor Solution
• USGS Body-Wave Moment Tensor Solution
• USGS WPhase Moment Tensor Solution
• Historic Moment Tensor Solutions
• Finite Fault Model
• Phase Data
• Seismicity Cross Section
• Seismic Record Section
• Theoretical P-Wave Travel Times
• Energy and Broadband Solution
• Subduction Zone Geometry Analysis