Strong Quake Near Auckland Islands

A strong earthquake struck near the Auckland Islands late this morning, the fourth significant quake to have struck New Zealand territory today.

The magnitude 6.1 earthquake, which struck at 11:34 a.m. on Sunday the 27th of April 2008, was located 230 km north-west of the Auckland Islands at a depth of 12 km. The epicentre was 430 km south-west of Invercargill, 210 km south-west of the Snares Islands. The quake was felt in Queenstown, Invercargill and Winton, but not strongly.

Earlier this morning, at 3:28 a.m., a magnitude 5.1 quake struck the Kermadec Islands. The quake was located 235 km north-north-east of Raoul Island at a depth of 190 km.

At 7:41 a.m. a shallow magnitude 4.7 quake struck to the east of Cook Strait. The quake was located about 300 km east of Blenheim at a depth of 33 km.

A magnitude 4.5 quake struck at 9:32 a.m. This quake was located about 220 km north of East Cape, 360 km east of Whangarei at a depth of 230 km.

[Compiled from data provided by the Geonet project and its sponsors EQC, GNS Science and FRST; and the US Geological Survey and its contributing agencies.]

2 Responses to “Strong Quake Near Auckland Islands”

  1. Darren says:

    Hey – why is that the recent large quakes in that area north of Macquarie Island and south of Fiordland don’t seem seem to be followed by aftershocks? Any idea? Is it the fault type?

    Cheers!
    daz.

  2. Ken says:

    It is generally accepted that most large shallow earthquakes have aftershocks, but three factors are involved – time, fault structure and coverage –

    Perhaps sufficient time has not passed for the larger aftershocks to occur – the largest aftershock can be within 1 order of magnitude of the main shock and occur late in the sequence.

    The structure of the rock in the location of the quake may mean that the fault interface is not smooth and it has jammed up again. This implies that the event was a foreshock and that strain is still accumulating pending the main event.

    Coverage in the Southern Ocean is not as good as in populated parts of the world, so there will be many smaller quakes that are not detected and the medium-sized beasties are not reported due to lack of public relevance. (USGS publishes info on mag 4.5 or above events in many parts of the world, but NOT near NZ nowadays. Usually it has to be above 5, some distance away from our coasts, and publication can occur days after the event).

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