Great Quake Near Tonga and Samoa

A very strong undersea earthquake struck the Tonga/Samoa region just before 7 o’clock this morning. A tsunami warning has been issued for several Pacific Ocean locations, including New Zealand.

Wednesday 30th September 2009

An earthquake with a magnitude between 7.9 and 8.3 struck 160 km east-north-east of Hihifo, Tonga (205 km south-south-west of the Samoan capital Apia) at 6:48 this morning, New Zealand Daylight Time. The undersea quake was 35 km deep according to initial estimates.

The U.S. Geological Survey estimates the earthquake at magnitude 7.9, and Geoscience Australia has reported the quake at magnitude 8.1 at the shallower depth of 5 km. They estimate the shaking would have caused damage within 300 km of the epicentre, and would have been felt up to 3700 km away.

The Pacific Tsunami Warning Centre (PTWC) issued a bulletin at 7:04 a.m. reporting the quake at magnitude 7.9 and announcing a tsunami warning for Pacific islands near the epicentre, as well as the Kermadec Islands and New Zealand. The epicentre is about 2700 km north-north-east of Auckland and a wave, if one was generated, would take about 3 hours to reach East Cape, arriving around 10 a.m. The PTWC bulletin estimated arrival times of 9:44 at East Cape, 10 a.m. at Gisborne, 10:50 at Wellington and 11:55 at Lyttelton.

The PTWC issued a second bulletin at 7:56 New Zealand Daylight Time upgrading the earthquake to magnitude 8.3 at a depth of 33 km. Early measurements of the tsunami wave were 70 cm at Apia and 1.6 metres at Pago Pago American Samoa. Estimated arrival times for New Zealand remain unchanged.

[Compiled from data supplied by the U.S. Geological Survey and its contributing agencies; the U.S. National Oceanic & Atmospheric Administration’s Pacific Tsunami Warning Centre, and Geoscience Australia.]

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