OLIVIA WANNAN AND NICOLE MATHEWSON
A large fault line discovered beneath Wellington Harbour shakes every "several thousand" years, scientists say.
A previously unknown fault zone with the potential to severely damage New Zealand's capital has prompted fresh calls for vigilance from quake-hardened Cantabrians.
The Aotea Fault has lain beneath Wellington Harbour giving no hint of the havoc it could unleash every few thousand years.
And the message to locals is: Do not panic, but get ready.
"This doesn't change the overall hazard map for Wellington but let's use this as a useful reminder. . . to get prepared," Mayor Celia Wade-Brown.
Canterbury Communities' Earthquake Recovery Network spokeswoman Leanne Curtis urged Wellingtonians to learn from Canterbury's earthquakes.
"Know your insurance policy - just read it, understand it and make sure that you are in the position that you want to be in for a start." She encouraged Wellingtonians to get to know their neighbours, as they would need to rely on each other if disaster struck, especially if they were elderly or disabled.
"Ultimately, the first response isn't the ambulance, emergency services and all that, the first response is your neighbours."
Local and central Government also had lessons to learn, particularly regarding rebuilding and communication, Curtis said.
Lincoln University lecturer Ann Brower, the sole survivor of a bus crushed by a collapsed building in Colombo St, said authorities were being too "optimistic" about how Wellington would cope if a big earthquake struck.
Wellingtonians had an "attitude of awareness" about earthquakes so thought they were prepared for a disaster, she said.
"I was really well aware of earthquakes . . . but awareness doesn't help you when a building falls on top of you."
Brower called for authorities to focus on making buildings with unreinforced masonry safer, saying ignoring them was "not acceptable".
National Institute of Water and Atmospheric Research marine geologist Philip Barnes said the newly-found fault was capable of producing a shake of up to magnitude 6.3 to 7.1. But how often it ruptured could only be narrowed down to every "several thousand" years.
The last big shake scientists could spot in its geological record was 6200 years ago.
"We've recognised at least two earthquakes on this fault in the last 10,000 years and possibly three. . . but some faults have a lot of variability in their recurrence." Barnes said the active fault begins approximately 1km east of Westpac Stadium and ran south-west for at least 2km.
Estimated to be between 10 and 30km in length, the fault runs toward the land, with several separate "traces" of the fault running toward the new multi-million dollar development at Clyde Quay Wharf, to Chaffers Marina and Oriental Bay Beach.
The active fault joins dozens running through the city and Barnes did not rule out further ones being found in Wellington.
The fault was first discovered two years ago. Since then, researchers have mapped its path, size and history before making a public announcement.
Barnes said the newly-found fault was smaller and caused quakes less frequently than its Wellington or Hikurangi counterparts. While a magnitude 7 quake from the Aotea Fault would cause damage to the capital, it would be less than if either the Wellington Fault, which ran down the Hutt Valley, or the offshore Hikurangi Fault ruptured.
Wade-Brown said she did not believe the newly discovered fault raised the tsunami risk of the city.
The size of earthquakes the Aotea Fault could cause were already planned for in the capital's current building codes, she said.
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