Quake expert gives warning

ADAM ROBERTS
Last updated 13:00 31/07/2013
Dr Mark Quigley
ALDEN WILLIAMS/ Fairfax NZ
CONSIDERATE: Dr Mark Quigley urges people to consider where they're building based on seismic history.

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Nelsonians need to "personalise their hazard" and take more notice of the seismic history of locations where they want to build, an earthquake expert says.

University of Canterbury senior lecturer in active tectonics and geomorphology in the department of geological sciences Mark Quigley gave the Geoscience Society's Hochstetter Lecture at the Old St John's on Hardy St last night.

He spoke on the geological and geomorphic impacts of the 2010-2012 Canterbury earthquake sequence and local evidence for large prehistoric earthquakes, focusing on his research into prehistoric earthquakes in the region.

Speaking before the talk yesterday, Quigley said despite the record of earthquakes in the Canterbury region, particularly of a cluster of quakes in the 1990s, there had been a bit of a "not in my backyard" attitude in Christchurch before 2010.

But since 2010, the region had experienced about 40 earthquakes of magnitude 5 or greater, which all had the potential to do damage.

The geological record supported the idea that significantly damaging events would be well spaced out, but the country was still at an elevated risk level due to their frequency and tendency to cluster together.

His research had also shown that locations with current geological activity almost always had prehistoric activity as well, meaning they would almost definitely have activity again. This had significant implications for those looking to build, he said.

"If you're building a house in Nelson and there's evidence of rockfall, there's no reason to think it's not going to happen again."

While it was human nature to have a "fatal attraction" to such locations, people needed to be smarter about where they chose to live, he said.

"Personalise your hazard, have a good hard think about what the location of the property means for you and your personal hazard."

It was cheaper and smarter to be proactive with bringing buildings up to a high standard, rather than waiting for the quake to eventuate and tidying up afterwards, he said.

"It costs the country, but we also live right on top of a plate boundary so that's our seismic reality."

There was plenty of information online, with detailed maps of the identified faults and their seismic histories, but there were also likely to be a lot of faults unknown to the scientific community, he said.

Most earthquakes which led to deaths occurred on such "blind faults".

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- The Nelson Mail

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