Quake experts discusses NZ’s alert system and preparedness

New Zealand won't be getting an earthquake early warning system any time soon, Earth Sciences says.

Countries like Japan, which suffered a large quake last week, use technology that can alert the public before damaging tremors happen.

New Zealand has been hit by multiple earthquakes in the past 10 days beginning with the first of two quakes in Te Anau, on 25 July, followed by a strong 5.9 quake in Taumarunui on 26 July. A 5.7 earthquake struck Te Araroa on the East Cape on 2 August.

Earth Sciences principal scientist Bill Fry told Morning Report the technology used to warn people seconds before an earthquake struck, relied on two basic principles - that shaking radiated away from the source and that the first shake wouldn't be the strongest.

"So based on these two things, the Japanese and others, have found ways to look at earthquake waves very close to the source and give some seconds of warning."

He said sensors close to the source of the shaking could help predict the strength and direction of the tremors, while other technology used light shaking to predict stronger shaking at a single point.

Fry said instead of an early alert, New Zealand focused on a rapid response.

"There are other lower-hanging fruits. We've decided to use the same technology as earthquake early warning to try to give us a rapid understanding of places that might have experienced strong shaking and shaking damage."

He said that information would feed into the emergency response.

In places that had early warnings - like Japan - systems existed to shutdown infrastructure such as high-speed trains and machinery, Fry said, but the prospect of implementing something similar in New Zealand raised many questions.

"A lot of those questions are in the social science. If we could deliver some seconds or tens of seconds warning, how would that be taken by people and how would they take appropriate action to ensure their safety?

"How would it be used?"

Fry said researchers were actively trying to answer those questions.

He said to date, the country had the science and technology to understand earthquake waves and their effect on the ground.

"We have it in use in response mode, we don't have it in use prior to the earthquakes arriving and that's really because we have a lot of work left to do, to understand how best to do that for New Zealand."