Water under NZ causing quakes

New evidence shows water beneath New Zealand is giving us the shakes.

Scientists used electrical currents running deep in the crust of the earth to measure how water underneath New Zealand was triggering powerful earthquakes and causing new volcanoes.

A new study adds more evidence to the theory that water plays a major role in weakening the crust of the earth, causing shearing and deformations.

Paper co-authors Grant Caldwell and Hugh Bibby say because the tectonic plates underneath New Zealand are actively deforming, they promote electrical activity deep in the earth.

If water is present, currents could form where heat from the earth's core softens the rock's structure, they said.

"Measurements of the low frequency electromagnetic waves produced by solar activity and world-wide thunderstorm activity allow us to see electrically conductive zones deep within the earth.

"This provides information on the deformation occurring beneath the part of the fault that breaks in large earthquakes, and insight into the mechanisms that ultimately cause earthquakes," they said.

The study was carried out by an international team including New Zealand scientists, and was published in scientific journal Nature.

It measured a line of deep electrical currents across Marlborough that matched up with major fault lines.

The information also provided insight into the creation of gold and other metals that move around at active plate boundaries.

Massey University Earth Scientist Bob Stewart said the study could have import-ant implications for finding gold deposits, as well as understanding major earthquakes.

"It has given us quite an exciting new insight to the behaviour of faults in the deep to middle crust.

"It will help pin down more closely where earthquakes will occur and the probability of them occurring."

New Zealand's unstable position, perched precariously on the edge of a tectonic boundary, is one of the few places in the world that these processes can be observed from land.

Manawatu Standard