Major Quake, Vanuatu

A major earthquake struck Vanuatu this morning, triggering a tsunami warning for nearby areas.

Friday 28th May 2010

A magnitude seven earthquake struck Vanuatu at 5:15 this morning, New Zealand time, triggering a tsunami warning from the Pacific Tsunami Warning Centre.

The U.S. Geological Survey reports the earthquake as magnitude 7.2 located 215 km north-north-west of Luganville, Espiritu Santo (340 km south-south-east of Lata in the Santa Cruz Islands) at a depth of 36 km.

The Pacific Tsunami Warning Centre (PTWC) initially reported the quake as magnitude 7.6 and issued a tsunami warning for the Solomon Islands, Vanuatu and New Caledonia at 5:27 a.m. New Zealand time. This bulletin contained incorrect estimates for initial arrival times and was swiftly corrected in a bulletin issued at 5:39 a.m., which also revised the earthquake magnitude to 7.3.

The PTWC issued a further bulletin at 6:38 this morning cancelling the warning and advising that sea level readings did not show any tsunami activity.

Geoscience Australia reports the quake as magnitude 7.6 at a depth of 60 km. It estimates that the quake would have caused damage within about 200 km of the epicentre and would have been felt up to 2200 km away.

New Zealand’s Ministry of Civil Defence claims to have issued an advisory for the event but, at this stage, details are only available to subscribers of the private information service, Twitter. The Ministry’s website briefly showed a small panel containing, “VanuatuQuake The tsunami advisory has been cancelled Update2 Scientific analysis suggests that there is no threat to New Zealand based on the earthquake magnitude, location and orientation to New Zealand. However the National Crisis Management Centre will remain monitoring the situation for a while in case there are any changes to the scientific advice.” This has since been removed.

According to the Tsunami Advisory and Warning Plan issued by the Ministry in February, an earthquake greater than magnitude 7.5 in region 1, which includes Vanuatu, should trigger the issue of a national advisory of a potential threat to New Zealand (page 11) but it is not clear whether this would only be publicly issued to users of the Twitter service.

As at 9:15 this morning, four hours after the earthquake, details of MCDEM’s advisories were still not available via its website, unlike the advisories for the Chilean quake in February.

Earthquake activity following the major quake has continued, with magnitude 5.7 and 5.2 aftershocks at 5:24 and 5:45 this morning. An earthquake of magnitude 6.0 to 6.4 was reported nearby (215 km north-north-west of Santo, Luganville) at 8:48 this morning and is still being assessed by the U.S. Geological Survey and Geoscience Australia.

The area has been active during the past week, with earthquakes reported near Vanuatu, the Santa Cruz Islands and the Loyalty Islands.

On May 21st, four earthquakes with magnitudes between 4.6 and 4.9 were reported in the Loyalty Islands, followed by a magnitude 5.3 event on the 22nd. Quakes of magnitude 5.0 and 5.5 were reported near Vanuatu on the 23rd and 24th of May. Two quakes of magnitude 4.7 and 4.8 were reported in the Santa Cruz Islands on the 25th and 27th of May.

[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.]

One Response to “Major Quake, Vanuatu”

  1. Ken says:

    Update –
    On Radio New Zealand National’s midday news it was reported that the MCDEM advisories for this event were not even released to the media. On the bulletin MCDEM claimed that this was due to human error at the New Zealand Fire Service.

    The key issue here is, if MCDEM can’t publish its advisories promptly on its own website, then how can the public attempt to find important information when the Ministry’s warning arrangements fail, as they so often do.

    This must be a disappointment for the CD sector following the dramatically improved performance by MCDEM during the Chilean quake and tsunami event in February. That event occurred at such a distance that authorities had half a day to respond. Had this morning’s quake near Vanuatu generated a tsunami of significance to New Zealand, it could have arrived at our shores within three hours.

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