Mapping the great wall of Waiau
‘‘We couldn't do any of our work if we didn't get access to the land.’’
The ‘wall of Waiau’ became a striking image of the North Canterbury earthquakes.
Data from the fault scarp was included in that collected by the University of Canterbury’s Department of Geological Sciences in the Waiau region in the past year.
Geologist Dr Kate Pedley, a member of the Rangiora Photographic society, and the geology team headed north to find ruptures in the Waiau region around the original epicentre just days after the magnitude 7.8 earthquake.
‘‘We were up in Waiau two days after the earthquake for reconnaissance,’’ Pedley said.
‘‘The first week we were up there, we didn’t do any science. We just talked to people, checked if they were okay and explained what we were going to be doing.
‘‘We had a job to do but all of the team had been through the Christchurch quakes, so we knew what they were going through.’’
A former eastern Christchurch resident, Pedley was able to relate to the people and their experiences.
She said to really generate winwin post-disaster research outcomes which benefit researchers and local communities alike, ‘‘creating trusting and mutually respectful relationships with landowners and local communities is vital to the quality and effectiveness of data gathered, immediately after the event, but more importantly, for ongoing access to facilitate further indepth research’’.
‘‘In the past, we have been looking at fault traces that are hundreds, if not thousands, of years old so there is very little data left.
‘‘We are trying to make hazard models for the country from that. It’s not ideal. These kinds of events give us the raw data so it is important to get out there and collect it, but in that first week, it’s not going to disappear.’’
So the geologists took the time to deal with the locals.
‘‘We couldn’t do any of our work if we didn’t get access to the land.’’
After helping out as much as they could with the initial response, the scientists went to work.
Satellite imagery identified the areas of interest and they headed off to investigate the raw data.
‘‘We walked along fault traces – we have walked kilometres and kilometres of fault traces. It’s the best way to get accurate data as our GPS is accurate down to 2cm.’’
That’s when they came across ‘the wall’.
‘‘It was an interesting day for us.
‘‘The landowners, David and Rebekah Kelly, had come across it themselves and got quite a fright but hadn’t told us about it.’’
The group was following a fault scarp and were about to split into two groups to splinter off in separate directions.
‘‘Duncan (Noble) went off ahead over the hill and came over the radio saying, ‘‘guys you will want to come look at this’’.
Rather than head south, Pedley went north to investigate and came across the new land feature.
‘‘We had never seen anything like it.’’
The impressive structure was just one major post-earthquake feature they came across, including a new lake that had formed, also on the Kelly’s property.
Some farmers had filled in cracks, fractures and fault traces for stock safety and to carry on about their business, but were helpful in pointing out features they had noticed.
‘‘In that way we lost some data, but we were thankful a lot of the landowners let us in to take a look before they did.’’
After covering the reformed terrain on the ground, Pedley carried out an aerial survey of the more difficult terrain around the larger Waiau region by helicopter.
She described the experience as ‘‘six hours of pretty much doing sky donuts’’, with the door open to take photos.
The University of Canterbury team had someone out in the Waiau region every day for three months and have continued working the ‘‘southern structures’’.
Pedley said it might be a year on, but it’s still early days for the research.
‘‘We are already publishing some papers but there are piles and piles of data to go through.’’
Pedley said that as the Canterbury earthquakes reminded us, earthquakes are part of our reality living in this country.
‘‘New Zealand wouldn’t be here if it wasn’t for plate tectonics. Whether we like it or not, they’re here to stay.
‘‘They are not particularly nice but there is a lot we can do to protect ourselves, and make communities more resilient.
‘‘That’s what all of our work goes into. Contributing to the long-term preparedness.’’
Geologist Dr Kate Pedley mapping the North Canterbury Earthquake
Dr Kate Pedley at the fault scarp known as the wall of Waiau last year