Strong Quake, Fiji

A strong earthquake struck the southern Fiji islands this afternoon. The magnitude 6.2 quake, which struck at 3:03 p.m. on Thursday 3rd July 2008 New Zealand time was located 320 km south-south-west of Ndoi Island, Fiji, at a depth of 568 km according to the U.S. Geological Survey.

Geoscience Australia record the quake as magnitude 6.0 at a depth of 600 km. The quake would have been felt within 560 km of the epicentre.

[Compiled from data supplied by the U.S. Geological Survey and its contributing agencies, and Geoscience Australia.]

6 Responses to “Strong Quake, Fiji”

  1. Darren says:

    Any comment on the noise seen from Ruapehu?
    What do you make of it?

  2. Sean Wyseman says:

    This is confusing. An earthquake at a depth of 568 km that would have been felt within 560 km of its epicenter would not be felt within 8 km of the surface.

    This seems like a pretty deep earthquake. I’m no expert on earthquakes but the simple calculation seems to indicate that nobody would have felt this.


  3. Ken says:

    Sean, I think you are confusing epicentre with focus. The focus of this particular quake is a theoretical point 560-600 km under the Fiji islands where the earthquake occurred. The epicentre is defined as a point on the surface of the earth directly above the focus – in this case a location SSW of Ndoi Island.

    Incidentally, Geoscience Australia have revised their “felt radius” down to 458 km. I’ve had a look at USGS records and no reports of this quake being felt have been lodged with them at this stage.

    By way of comparison, the magnitude 5.5 Fiji quake of July 2nd (UT) was calculated to be 450 km deep by Geoscience Oz, and had a calculated “felt radius” of 278 km.

  4. Ken says:

    Hi Darren, this isn’t relevant to the Fiji quake but I’ll respond to your query here. It looks as if the bursts of activity at Ruapehu that you refer to could have been due to wind – outside the volcano, not in it 😉
    We’ve had several bouts of severe gale force winds in recent days.
    But then I’m no expert in interpreting RSAM and SSAM plots…

  5. Darren says:

    Lol… cheeky. 😉

    Nar – me nether Ken. I wish there was a explanation RSAM and SSAM online somewhere. The noise didn’t look like wind – normally Ngauruhoe shows wind noise before Ruapehu, and the short duration of the signals would be (in my view) inconsistent with noise from wind or weather.
    Then again – there’s a heap of new data avilable on GEONET now and learning to interpert that when compared to the old data is providing a few tripping points along the way…

    It seems to have stopped (or paused) now anyhow – so we watch and wait. Sorry to stuff up your blogs with subjects within subjects – would be cool if you had a general comment area to discuss events like this.
    Thanks for the response!

  6. Darren says:

    Nar – it’s not weather related.

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