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View Full Version : Small earthquakes could mean big trouble



Parihaka
01 Dec 05,, 02:44
Three earthquakes rattle New Zealand island

November 30 2005 at 02:06AM

Wellington - New Zealand scientists said on Wednesday that they were monitoring seismic activity at the edge of the Auckland volcanic field after three small earthquakes shook an offshore island.

Auckland, the country's biggest city with a population of 1,3 million, is built on six extinct volcanoes, but earthquakes are rarely felt.

Three shakes were recorded on Waiheke Island, 30km east of the city, in just over 12 hours, the last and biggest at a magnitude of 3.3 on the Richter scale on Wednesday morning.

Two tremors measuring 2.5 were recorded within the space of 11 minutes late on Tuesday night.

Seismologist Ken Gledhill told Radio New Zealand a series of quakes that size would not normally be considered significant, but the location was unusual and seismic activity would be monitored although there was no cause for concern at this stage.

No damage or casualties were reported but residents on Waiheke, the largest island in the Hauraki Gulf and renowned for its wineries, were said to have been rattled by the shakes.
We get heaps of earthquakes every year, two 5+ in Wellington last year alone, but Auckland is a different matter entirely. The article incorrectly states that their are six extinct volcanoes in Auckland, infact there are forty nine discreet volcanoes, all potentially active, within a twenty kilometer radius of Auckland central.

http://www.gns.cri.nz/what/earthact/volcanoes/nzvolcanoes/bookimages/auckav3.gif

Waiheke Island is to the right of the diagram. The last significant eruption (the island labelled rangitoto) was 600 years ago and we are overdue by 200 years for another one. Oh well, I never liked the city anyway....