Slow-slip East Coast earthquake to roll on for weeks
Last updated 20:23, June 23 2016
Scientists hope to better pinpoint the latest slow-slip event in the Gisborne 'silent earthquake' zone by using GPS stations.
Gisborne is in the grip of an earthquake so massive it has the power to move fault lines – but you wouldn't know it.
A "silent earthquake", or slow-slip event, has been building off the coast of Gisborne for about a week, GeoNet seismologist Caroline Little says.
Silent earthquakes are undetectable by humans or by GeoNet's seismographs, but they can move fault lines to the equivalent of a magnitude 5 tremor or more.
Gisborne - a hub of 'silent earthquake' activity - was struck by a normal magnitude 6.8 quake in December 2007, which destroyed buildings across the city.
They can be detected only by using GPS to measure ground movements of just a few millimetres.