New Zealand’s 7.0 earthquake was strongest to strike the region in 119 years

Wednesday, July 4, 2012
By Paul Martin
July 4, 2012

NEW ZEALAND – Last night’s magnitude 7.0 earthquake in the South Taranaki Bight is the largest to strike the region in more than 100 years, GNS Science says. The quake struck at 10.36pm, 60km south-west of Opunake in Taranaki, at a depth of 230km. It was felt strongly around the west coast of the lower North Island, and was widely felt from the Bay of Plenty to Canterbury. No tsunami was generated by the quake. Waiouru resident Adrienne Murphy told the Herald it was the “biggest shake we have felt in years.” Residents in Wellington reported being startled by shakes, which lasted for about 15 seconds. Some said the shakes were strong enough to topple household appliances, but the central Fire Service communications centre said it had received no reports of earthquake-related damage. Wellington resident Sam Rowe said he felt the walls of his house shaking. The South Taranaki Bight is no stranger to large earthquakes; A magnitude 6.4 earthquake struck on March 15, 2005, at a depth of 150km. Seismologist Lara Bland said the quake was the largest to strike the South Taranaki Bight in about 119 years. In 1893 a quake struck measuring about magnitude 7.2. Only one aftershock has been recorded following the quake – a magnitude 4.6 aftershock nine minutes later – although GNS Science will be doing a background check today to see if there were others. “But we’re not expecting a very rich aftershock sequence,” Ms Bland said. GNS Science said the quake was typical to other deep North Island tremors, in that the strongest shaking occurred to the east of the epicenter, rather than directly above it. “To an extent, an earthquake that large will often be felt reasonably widely anyway, but because of the subduction zone and where it occurred, the energy has travelled very efficiently back up the dipping plate that it has occurred on so it has come to the surface in a very efficient path,” Ms Bland said. Large earthquakes are not unusual in New Zealand, with a quake larger than magnitude 7 occurring on average every three years. –NZ Herald

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