Strong Quakes, Kermadecs

A pair of strong, shallow earthquakes has shaken the Kermadec Islands in recent days.

Thursday 19th February 2009

Today’s magnitude 6.9 earthquake was the second 6th magnitude event to strike the Kermadec Islands during the last two days.

The quake, which struck at 10:54 this morning, was located 250 km north-east of Raoul Island (1335 km north-east of Auckland) at a depth of 25 km, according to the U.S. Geological Survey. The quake, which GeoNet reports as magnitude 6.8 at a depth of 62 km, was felt in New Zealand, with reports of shaking being filed from Palmerston North, Paraparaumu, Wellington and as far south as Lincoln in Canterbury.

The Pacific Tsunami Warning Centre issued a bulletin at 11:04 a.m. NZDT advising that the quake was initially thought to be magnitude 7.3 at a depth of 36 km, but a widespread tsunami threat was thought unlikely. GeoNet’s tsunami gauges confirm the warning centre’s assessment, with no appreciable variation from normal being reported at the seven New Zealand monitoring sites during the 7 hours following the quake.

Geoscience Australia reports the quake at magnitude 7.2 at a depth of 63 km. They estimate that damage would have occurred within 121 km of the epicentre, and the event would have been felt up to 1500 km away, a distance which equates to the central North Island.

A deep magnitude 4.8 event was recorded close to today’s earthquake epicentre at 11:19 last night. However, this earthquake, which was located 225 km north-north-west of Raoul Island, was much deeper at 365 km.

A shallow magnitude 6.0 earthquake was recorded 70 km north-north-east of L’Esperance Rock in the southern part of the Kermadec Islands on Tuesday 17th at 4:31 p.m. This quake, which was located 900 km north-east of Auckland, is thought to have been only 10 km deep.

Shallow earthquakes of magnitude 5.4 and 5.8 were reported in the Kermadec Islands on Friday last week.

[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, GeoNet, and Geoscience Australia.]

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