Large earthquakes near Vanuatu

08 October 2009

A large potentially tsunamigenic earthquake has occurred in the Pacific Ocean this morning followed by a series of strong aftershocks. The magnitude 7.9 earthquake occurred approximately 500km north-north-west of Vanuatu at 9:03am AEST at a shallow depth of 38km below the seabed.

"At this stage we have had no reports of damage from the earthquakes, but this is not unexpected as the closest areas of significant population are outside the range of impact," said Senior Seismologist Dr Phil Cummins.

The earthquake was followed by powerful aftershocks; the largest two recorded at magnitudes of 7.4 and 6.8 occurring at 9:19am AEST and 10:13am AEST respectively.

"These aftershocks are very large, shallow and potentially tsunamigenic in their own right. Following this size earthquake we would expect to see a number of aftershocks in the coming days, and possibly weeks, gradually reducing in size and frequency", said Dr Cummins.

A tsunami watch was issued for areas of offshore North Queensland by the Joint Australian Tsunami Warning Centre following the initial earthquake, but was subsequently cancelled after further analysis.

"It is remarkable to have so many large earthquakes in such a short time, but we know of no direct connection between today's earthquake and the large events that impacted Samoa and Padang, Indonesia last week; although they are related as part of the Earth's ongoing dynamic processes", said Dr Cummins.

"This earthquake occurred where the Australian Plate slides beneath the Pacific Plate and releases stress which builds up due to this process. Earthquakes will continue to occur at the boundaries of the Australian Plate as it pushes slowly north-east at approximately 7cm per year, resulting in collisions with the Pacific, Eurasian and Philippine plates", said Dr Cummins.

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