Two strong, undersea earthquakes struck near Tonga this morning.
Friday, 24th May 2013
A magnitude 7.4 earthquake struck 282 km south-west of Vaini, Tonga (287 km south-west of the Tongan capital Nuku’Alofa) at 5:19 this morning, New Zealand time. The U.S. Geological Survey reports that the quake was 170 km deep.
The Pacific Tsunami Warning Centre reported the event as magnitude 7.4 at a depth of 200 km. It concluded that a destructive tsunami was not generated, based on the earthquake’s characteristics and historical data.
Geoscience Australia reported the quake as magnitude 7.5 at a depth of 100 km. It estimated that the earthquake would have caused damage within 160 km of the epicentre and would have been felt up to 2,000 km away.
Another undersea earthquake struck the area at 9:08 this morning, New Zealand time. The U.S. Geological Survey reports this event as magnitude 6.3 centred 84 km north-west of Nuku’Alofa at a depth of 154 km. The Pacific Tsunami Warning Centre reported this quake as magnitude 6.5 at a depth of 144 km.
Geoscience Australia reported the second earthquake as magnitude 6.3 at a depth of 100 km. It estimated that the quake would have caused damage within 50 km of the epicentre, and would have been felt up to 600 km away.
In summarising the larger earthquake, the U.S. Geological Survey noted that the quake was due to a rupturing of a fault in the descending part of the Pacific Plate and was not on the shallower interface between the Pacific and Australian tectonic plates. It noted that there have been more than a dozen earthquakes with magnitudes over 6.5 within 500 km of this morning’s event in the past 40 years. The largest was a magnitude 7.7 earthquake in October 1997.
[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.]