Mystery shaking far in the depths

Something unusual is stirring beneath Taranaki.

A series of seismic events some 600 kilometres below the province is attracting international attention and fascinating scientists.

Professor Tim Stern said the remarkable, "super-deep" earthquakes strike every 15 to 20 years and Taranaki was due for another.

Stern said that far from being an immediate threat to life and property, the quakes posed an intriguing question replicated in a few places around the world.

"These pop off every 15 to 20 years and the last one was in 1995. They are about a magnitude four or five, so you will probably feel them but they are certainly not going to cause you any problem."

He said the quakes are believed to be caused by a chunk of the Earth's crust releasing seismic energy as it "free falls" through the viscous mantle.

"There is a lot of international attention on this problem, and it's a Taranaki one."

Stern, along with Dr Rupert Sutherland, was in New Plymouth on Thursday to discuss New Zealand's seismic history and its impact on the economy and geology.

Sutherland urged the 200-strong crowd to think about how the country should use its natural physical resources.

He said much of New Zealand's exclusive economic zone was once part of the same land mass as Australia and could contain similar mineral wealth.

"We just don't know the answer yet because it is just so poorly explored," he said.

"The question is then, do we want to do anything with it, do we want to encourage this type of behaviour and use our natural resources.

"We have choices. We can either completely ignore it, forget about it and be a passive observer on the global economy, or fritter it away or use it wisely."

Taranaki Daily News