Auck­land’s ex­plo­sive past un­cov­ered

East and Bays Courier - - OUT & ABOUT - STAFF RE­PORTER

Sci­en­tists are fill­ing in the gaps of Auck­land’s tem­per­a­men­tal vol­canic past.

In stud­ies pub­lished this month, a team of re­searchers from De­ter­min­ing Vol­canic Risk in Auck­land found the Su­per City has had a com­plex and episodic erup­tion his­tory.

The oldest erup­tion, Pupuke, was about 200,000 years ago, while the most re­cent, Ran­gi­toto, was a mere 500 years ago.

How­ever, the time in be­tween erup­tions was in­con­sis­tent and un­pre­dictable, the sci­en­tists found.

Some­what alarm­ingly, more than half of Auck­land’s to­tal erup­tions have been in the past 60,000 years.

The re­searchers said that in­di­cated the rate of erup­tions has been in­creas­ing, al­though there had also been quiet pe­ri­ods of up to 10,000 years.

GNS Sci­ence se­nior sci­en­tist Dr Gra­ham Leonard, who led the re­search team, said some erup­tions flared up af­ter what was, ‘‘ge­o­log­i­cally speak­ing’’, a short pe­riod of time. ‘‘For ex­am­ple, there can be six to 10 vol­ca­noes erupt­ing within a 4000-year time­frame.

‘‘On the other hand, the vol­canic field has also gone quiet for up to 10,000 years in the last 60,000 years, which is quite a long gap.’’

Leonard said the new re­search was ‘‘ex­cit­ing’’ be­cause ‘‘it has al­lowed us to fur­ther de­fine when erup­tions have oc­curred which has helped us flesh out an erup­tion time­line’’.

Craig Glover, head of strat­egy and Plan­ning at Auck­land Civil De­fence, said the re­search showed that Auck­land’s vol­canic field was ‘‘un­pre­dictable.

‘‘We all need to be pre­pared and while it might seem daunt­ing, plan­ning for a vol­canic erup­tion is no dif­fer­ent to plan­ning for any other dis­as­ter – have a talk with your loved ones and make a plan.’’

Natalia Deligne from GNS Sci­ence pre­vi­ously said re­searchers had ‘‘no idea’’ when, or where, Auck­land’s next erup­tion would be.

They were ‘‘pretty con­fi­dent’’ there would be an­other erup­tion, but when it would come was any­one’s guess, she said.

Auck­land’s vol­canic field is the most densely pop­u­lated field of its type in the world.

In March, GNS Sci­ence re­leased a re­port say­ing the re­gion’s next erup­tion would likely come from a vol­cano that doesn’t ex­ist yet.

SUP­PLIED

One of many ex­plo­sion craters re­main­ing in the Auck­land vol­canic field.

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