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‘The reality is, it is not a matter of if, but when’
SUE TEODORO
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Tsunami, landslides, coastal uplift, and significant shaking could all be expected in Wairarapa in a big quake, according to a new earthquake simulation.
Seismo City seismologist Dr Caroline Holden, and East Coast Life at the Boundary project leader Kate Boersen have presented the findings of a study into how a simulated 8.9 earthquake in the Hikurangi subduction zone was likely to affect the region.
Boersen said such a subduction zone earthquake and tsunami could unfold in many ways.
“The reality is, it is not a matter of if, but when.”
The presentation at the Carterton Events Centre was to help residents and emergency responders prepare for a disaster.
There was evidence of 10 large earthquakes along the Hikurangi subduction zone in the past 7500 years of magnitude eight and above, meaning a magnitude 8.9 earthquake was a “credible event” for the area.
“My colleagues and I developed a challenging but credible science scenario for the Hikurangi Response Planning scenario to help emergency managers plan for a Hikurangi subduction zone earthquake and tsunami,” Holden said.
The 8.9 scenario developed was based on credible science but was just one of thousands of different possible scenarios.
“In this scenario, the Wairarapa region would experience strong-to-severe earthquake shaking for at least half a minute.
“The long and strong shaking from this earthquake would be the natural warning sign for people along the coast and near lakes to evacuate.
“We would expect to see widespread landslides on steeper slopes and liquefaction would occur in silty and sandy low-lying areas. In this scenario, we expect large uplifts of three to four metres along the South Wairarapa coast,” she said.
Boersen stressed earthquake response and planning would help communities when the time came.
“This is why it is so important to make sure people practise your drop, cover and hold, and tsunami hīkoi to high ground or inland by foot or bike.
“We know that practising these two things works because it helped save more than 95 per cent of people who safely evacuated in time in the 2011 Japan tsunami,” she said.
She hoped sharing the latest Hikurangi subduction zone science and hazard impact information with communities would spark informed and practical conversations about what to do in an evacuation.
Featherston Community Board deputy and representative on the Wellington Regional Emergency Management Committee Claire Bleakley was at the Carterton presentation.
“The concerns I had when I came away [from the presentation] is South Wairarapa appeared to be totally unprepared for such an event.
“I am concerned about how we would respond to an emergency in our coastal communities,” she said.
“Ngawi only has a coastal road, which could be severely damaged or destroyed in a major earthquake.”
Bleakley said South Wairarapa District Council needed to address the issues around what would happen, with a magnitude seven or eight earthquake event relatively soon a real possibility.
“We need to be prepared. We need to have better planning,” she said.
