New Zealand capital Wellington has been subject to continuous earthquakes for the past three years, according to Earthquake Commission (EQC) CEO Ian Simpson.

The “slow slip” events have been occurring 40 kilometres below the surface of the city.

Unlike a conventional earthquake that releases its energy suddenly with destructive effect, a slow slip or silent earthquake takes much longer to move and release energy.

Currently the Pacific plate is descending westward beneath eastern North Island, but part of it is stuck to the rising Australian plate.

Mr Simpson told a Victoria University lecture in Wellington last week some of this stress is being released with these slow slip earthquakes.

If these types of earthquake had occurred suddenly, they would have had the effect of a magnitude-7 earthquake.

Meanwhile, the EQC is giving Auckland University a $NZ60,000 ($56,000) grant to look at how a large volcanic eruption beneath Lake Taupo would affect the country.

The grant to Simon Barker will be used to map out eruption scenarios from the lake using a computer modelling system developed by the US Geological Survey.

Dr Barker says the modelling predicts where the ash clouds would travel, depending on climatic factors including seasons and wind directions.

“This will allow us to forecast how thick the resulting ash deposits would be around the North Island,” he said.

While there are no predictions of the next eruption, Dr Barker says the Taupo volcano is capable of rapidly moving into a new eruptive cycle.