Undersea Earthquakes in the Kermadecs

A burst of earthquake activity has struck the Kermadec Islands in recent days.

Thursday, 4th February 2016

A burst of undersea earthquake activity has struck the Kermadec Islands this afternoon, following Tuesday’s deep magnitude six event.

Today’s shallow activity began at 1:08 p.m. New Zealand Daylight Time with a magnitude 5.2 quake centred 144 km south of Raoul Island at a depth of 10 km. The U.S. Geological Survey reported three earthquakes in the series, with a magnitude 5.1 quake being recorded at the same location and depth at 1:48 p.m. A magnitude 4.9 quake struck nearby at 1:59 p.m., being centred 146 km south-south-east of Raoul Island at a depth of 10 km.

Today’s shallow earthquake activity is not directly associated with the much deeper earthquake felt in many parts of the North Island on Tuesday morning at 8 o’clock. This magnitude 6.2 earthquake was centred closer to New Zealand according to the U.S. Geological Survey. It reports the epicentre as being 120 km west-north-west of L’Esperance Rock in the southern part of the Kermadec Islands, at a depth of 382 km. Their calculation put the quake 749 km north-east of Whangarei.

GeoNet reported Tuesday’s 8:01 a.m. earthquake as magnitude 6.6, centred 850 km north-east of Whakatane at a depth of 366 km. The size, depth and location of the earthquake meant that it was widely felt along eastern coasts of the North Island. The earthquake epicentre was on a segment of the Pacific tectonic plate that dives deep down under the Earth’s crust where it will eventually melt and be recycled. Energy released by the quake travelled back up the descending slab and was transferred to the Australian tectonic plate (on which the North Island lies) along the eastern coast of the North Island where the two plates are in contact. Residents of the Gisborne and Hawke’s Bay areas felt the quake more than people living further south. New Zealanders from Tauranga to Christchurch reported feeling the earthquake, according to GeoNet.

GeoNet’s report and shake map for Tuesday’s earthquake can be found here.

[Compiled from data provided by the U.S. Geological Survey and GeoNet.]

One Response to “Undersea Earthquakes in the Kermadecs”

  1. Lizzie from Gizzie says:

    thankyou for the clear concise information Ken. Thank goodness someone can provide decent information.

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