1 Apr 2010

Small quakes edging Gisborne to the east

6:58 am on 1 April 2010

Scientists say the earth mass beneath Gisborne has moved between 35 and 100 millimetres to the east in the past three months.

They have monitored three events involving the Pacific Plate and the overlying New Zealand crust.

Scientists have detected 35mm of movement on the surface and about 100mm 12km to 15km down, where the plate meets the crust.

The movement is normally westwards at a few millimetres a year because the Pacific plate is moving in that direction.

But the locking between the plates and the New Zealand crust has been temporarily released, allowing movement back to the east.

GNS scientist John Bevan says the releasing of the pressure reduces the risk of earthquakes in that zone.