12 Nov 2017

Quake scientists converge on Marlborough

7:20 am on 12 November 2017

Marlborough's earthquake-creased hills and recent fault line ruptures will be the focus of a convention of international earthquake scientists over the coming week.

Two geologists standing in a trench

GNS scientists Russ van Dissen and Jamie Howarth inspect the Kekerengu fault rupture in south Marlborough in the days after the 2016 Kaikōura earthquake. Photo: RNZ / Tracy Neal

More than 100 overseas scientists have joined about 20 more New Zealand geologists in Blenheim to begin a workshop on active fault lines and ancient quakes in New Zealand.

The eighth annual International Workshop on Paleoseismology, Active Tectonics and Archeoseismology is being held in the Southern Hemisphere for the first time, said New Zealand earthquake geologist and convenor Kate Clark.

"We have about 130 people coming - 110 are from overseas, and what we will get from them is the dialogue, talking about what techniques, methods and findings people are getting from overseas which we might not necessarily be using here.

"We'll also be discussing with other people what we're doing here, and getting feedback," Dr Clark said.

Scientists working on the Kaikōura quake would also be attending, she said.

"It's really a great opportunity for us to find out what other people have been doing in terms of research on the Kaikōura earthquake."

Dr Clark said New Zealand was selected for this year's conference after several years' discussion with the international organisers.

"The reason we wanted it here in 2017 was to mark the tri-centenary of the Alpine Fault earthquake. Being an earthquake geology group everyone was keen."

The fault line that extends much of the length of the South Island is considered to be one of the fastest slipping faults in the world. Geological studies show it has ruptured regularly between every 200 to 500 years. The last time was in 1717.

Dr Clark said the magnitute-7.8 earthquake in Kaikōura a year ago has become a case study for scientists around the world.

"There is heaps to learn from the Kaikōura earthquake but also a lot to learn from other fault lines in New Zealand, like all the research we've done on the Alpine Fault.

"So places around the world where they haven't had a recent, large surface-rupturing earthquake - it's really valuable for those scientists to come here and make observations of what happened."

Dr Clark said there are plenty of other areas of interest in New Zealand.

"Blenheim is actually the spot where I have found evidence of two, large subduction earthquakes, so we know a lot about the Alpine Fault and we know when the last 24 earthquakes on it were.

"We haven't been trying to do that research along the Hikurangi margin as much, but that doesn't mean it's less of a risk."

The Hikurangi fault, offshore from the North Island's east coast down to Cook Strait, is capable of generating a quake equally as large as the Alpine Fault.

Dr Clark said New Zealand scientists also would benefit from hearing what the overseas experts were doing with quake studies in places like Europe and the US.

The workshop begins with a field trip to view some of the northern fault ruptures of the Kaikōura earthquake, followed by three days of talks and presentations at conference venues in Ward and Blenheim.

A post-meeting field trip will start in Blenheim and finish in Christchurch.

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