Map­ping the great wall of Wa­iau

Northern Outlook - - YOUR LOCAL NEWS - JONATHAN LEASK

‘‘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.’’

SUPPLIED

Ge­ol­o­gist Dr Kate Ped­ley map­ping the North Can­ter­bury Earth­quake

Dr Kate Ped­ley at the fault scarp known as the wall of Wa­iau last year

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