Sharp earthquakes hit already rattled country

Six hundred and fifty aftershocks have rattled the country in less than 24 hours after a big 7.5 magnitude quake hit in the early hours of this morning.

The first quake, which struck shortly after midnight. claimed the lives of at least two people and caused billions of dollars of damage to infrastructure in cities and towns and blocked off road access to the popular tourist town of Kaikoura.

Since the early morning tremour GeoNet duty seismologist John Ristau said 650 aftershocks had been recorded in the area, with at least forty greater than magnitude five and at least three of thse above magnitude six.

A cluster of larger aftershocks was felt by thousands earlier this evening - with two 5.8 magnitude quakes hitting in quick succession at 8:21, to the east of Seddon.

The first hit at a depth of 25km, 25km to the south-east of the town and the second at a depth of 23km, 20km to the east.

The duo followed another couple of smaller quakes, the first a "severe" 5.6 quake which also hit 20km to the east of Seddon, at a depth of 23km at 7:43pm, the second a magnitude 5.8 "strong" quake, which hit 25km to the east of Kaikoura at a depth of 40km.

Thousands from as far south as Canterbury and as far north as Auckland have already reported feeling the sharp jolts within the last 24 hours.

This evenings larger aftershocks were amongst the strongest felt since the larger quake woke thousands from their slumber, led to a tsunami alert and a widespread evacuation notice along the east coast.

While Ristau said it would be concerning for those being rattled by the quakes the tremours were the typical part of the aftershock sequence.

"Typically in an aftershock sequence we get less and less of the larger aftershocks."

However, Ristau said things were unlikely to completely quiet down anytime soon and expected a few more would rattle the central part of the country overnight and into the coming days.

He said within the next 24 hours there was a 12 per cent probability of a quake hitting that was magnitude seven or above.

"A really large earthquake like this is most likely to happen within the next few days, and as time goes on the probability will drop quite quickly."