Auckland has been hit by its largest earthquake since the 1890s.

A 3.7 magnitude quake shook the region at 8:24pm.

It was shallow - at six kilometres below the surface.

A second, larger tremor struck at nine o'clock and registered 4.5 on the Richter Scale.

It was at a depth of 15 kilometres.

Seismologist Bryan Field says it was one of the larger earthquakes Auckland has had in its history, but he doubts it will have caused serious structural damage.

Dr Field says two consecutive small earthquakes can mean a larger one is to follow - but he believes this is NOT the precursor for a large earthquake.