Wild Land

Two major undersea earthquakes struck Vanuatu this morning.

Sunday, 21st August 2011

A pair of major earthquakes struck beneath the Coral Sea in the vicinity of Vanuatu this morning New Zealand time.

The first of the pair, with a magnitude between 7.1 and 7.5 struck at 4:55 a.m. New Zealand time. The U.S. Geological Survey reports this event as magnitude 7.1, centred 63 km south-south-west of Port Vila on the island of Efate, 190 km north-west of Isangel, Tanna at a depth of 41 km.

Geoscience Australia reports this event further south as magnitude 7.5 at a depth of 1 km. It estimates that the quake would have caused damage within 164 km of the epicentre, which includes the islands of Efate and Erromango, and would have been felt up to 2,000 km away.

The Pacific Tsunami Warning Centre reported the event as magnitude 7.5 at a depth of 10 km. In a bulletin issued at 5:04 a.m. it advised that a widespread tsunami threat did not exist as a result of the earthquake.

The second quake of the pair, with a magnitude between 7.0 and 7.4 struck at 6:19 this morning, New Zealand time. The U.S. Geological Survey reports this earthquake as magnitude 7.0, centred 69 km south-south-west of Port Vila, 177 km north-west of Isangel, at a depth of 29 km.

Geoscience Australia reports that this event was centred slightly further south, with a magnitude of 7.4 at a depth of 0 km. It estimates that the earthquake would have caused damage up to 150 km from the epicentre, which includes the islands of Erromango and Efate, and would have been felt up to 1800 km away.

The Pacific Tsunami Warning Centre issued one bulletin for this event, reporting the quake as magnitude 7.4 at a depth of 36 km. The bulletin, issued at 6:28 a.m., advised that a widespread tsunami threat did not exist.

News reports indicate that the quakes have caused landslides at various locations in Vanuatu, but a significant tsunami wave was not observed.

Nine aftershocks with magnitudes between 4.9 and 5.9 have struck the area since this morning’s activity began.

[Compiled from data supplied by the U.S. Geological Survey, The Pacific Tsunami Warning Centre, Geoscience Australia, and their contributing agencies.]

This entry was posted on Sunday, August 21st, 2011 at 2:44 pm and is filed under Earthquakes - Observations. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.