Strong Quakes, New Guinea

Two strong undersea earthquakes struck the New Britain region of Papua New Guinea this morning.

Monday 19th July 2010

Two earthquakes struck beneath the Solomon Sea off the coast of New Britain island, Papua New Guinea early this morning.

The first quake, a magnitude 6.9 event, struck at 1:04 a.m. New Zealand time. This was located beneath New Britain island, 75 km south-south-east of Kimbe, 110 km east of Kandrian at a depth of 58 km according to the U.S. Geological Survey.

Geoscience Australia reports the event as magnitude 6.6, centred on the coast of New Britain at a depth of 60 km. It estimates that the earthquake would have caused damage within 70 km of the epicentre, which includes central New Britain, and would have been felt up to 800 km away.

A larger earthquake struck the area half an hour later when a magnitude 7.3 quake struck at 1:35 a.m. New Zealand time. This event was also centred beneath New Britian island, 65 km south-east of Kimbe, 105 km east-north-east of Kandrian (525 km north-east of the capital Port Moresby), at a depth of 58 km according to the U.S. Geological Survey.

Geoscience Australia reports this event as magnitude 7.0, centred just off the southern coast of New Britain island, at a depth of 18 km. It estimates that the quake would have caused damage within 100 km of the epicentre and would have been felt up to 1200 km away.

The Pacific Tsunami Warning Centre issued a bulletin at 2:10 a.m. New Zealand time reporting the larger quake as magnitude 6.8 at a depth of 63 km, and advised that a widespread tsunami threat did not exist. In a bulletin issued at 3:37 a.m. the PTWC revised the quake to magnitude 7.3 at a depth of 63 km and advised that sea level readings indicated that a tsunami had been generated, but a threat did not exist outside the immediate area.

In a third and final bulletin issued at 3:45 a.m. the PTWC retracted the tsunami observation, advising that no tsunami had been observed.

Three aftershocks with magnitudes between 4.9 and 5.1 have been reported in the immediate area by the U.S. Geological Survey.

[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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