New report reclassifies faults

A new study has identified 48 earthquake faults in the Central Otago and Queenstown Lakes areas, one of which has been remapped as running through the middle of Wanaka town.

The Otago Regional Council yesterday noted the new report outlining active, possibly active or potentially active faults in the districts.

Of those 21 were described as "definite" or "likely" faults, six were classed as "possible" active faults and another 21 were "potentially active".

The most active faults were the northwest Cardrona fault, with a recurrence interval of 5500 years, and the Lindis Pass fault zone, at 5600 years.

The northwest Cardrona fault was re-mapped as extending north from the Cardrona valley, near the foot of the Mt Alpha range, and through the middle of Wanaka itself.

Previously, it was thought to extend northeast to Lake Hawea, passing beneath Albert Town and part of the Lake Hawea township.

The other seven faults which had a recurrence interval of less than 10,000 years were the Dunstan fault zone, Gimmerburn fault zone, Highland fault, Livingstone fault, Motatapu fault, Nevis fault zone, and the Timaru Creek fault.

A major Queenstown fault was significantly downgraded.

The Moonlight fault runs through Lake Wakatipu. It was previously regarded as one of the most active faults in the area, with a recurrence interval of between 6000 and 7000 years, but is now thought to have an interval of more than 100,000 years.

Council natural hazards analyst Ben Mackey said the work was part of a region-wide review which would be broken down into districts.

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