Strong NZ currents after Chile quake

Currents in New Zealand east coast areas are likely to be stronger than usual today as a result of yesterday's 8.2-magnitude quake off the coast of northern Chile.

The Ministry of Civil Defence and Emergency Management said currents were likely to be strongest in harbours and estuaries.

"Unusual currents should be expected for all of Thursday. People on beaches or boats should take additional care."

Meanwhile, seismologists are warning the quake is not the big one expected off Chile, where the Nazca tectonic plate plunges beneath the South American plate.

Pressure along the fault is greatest off far northern Chile where yesterday's quake happened, an area known as the Iquique seismic gap.

The 8.2-magnitude quake yesterday  was not the large quake expected for the area, California Institute of Technology geophysicist Mark Simons told The Washington Post.

"We're actually still expecting potentially an even larger earthquake."

Iquique was the one remaining gap that had not had an earthquake in the past 140 years, Simons said.

"We know these two plates come together at about 6, 7 centimetres a year, and if you multiply that by 140 years then the plates should have moved about 11 metres along the fault, and you can make an estimate of the size of earthquake we expect here."

A magnitude-8.8 earthquake occurred within the Iquique gap in 1877, which was preceded immediately to the north by a magnitude-8.8 earthquake in 1868.