Two people have died following the earthquake which struck New Zealand at around midnight local time.
The deaths were confirmed by the country's Prime Minister John Key.
The earthquake was centred around the Christchurch area which was previously hit by a quake in 2011 that left many dead and the city badly damaged. It was followed by a series of smaller aftershocks – though, some are still measuring more than magnitude five – and a tsunami.
New Zealand's Ministry of Civil Defence and Emergency Management (MCDEM) has warned those on the east coast to move to higher ground. It said the first waves were expected to arrive at the Chatham Islands to the east of the main island, immediately and that there will continue to be tsunami activity for some time.
The shocks from the quake were felt in Wellington, New Zealand's capital city on the north island and as far as Auckland further north, and most of both islands to some degree
The Pacific Tsunami Warning Centre noted the power of the earthquake could be as much as magnitude 7.9.
Earthquake sirens could be heard alerting people to the situation.
And some have experienced damage as a result of the quake.
The extent of both the earthquake and the tsunami have not yet been determined. New Zealand is located where the Australia and Pacific tectonic plates meet, creating several trenches and fault lines in the area.
This breaking news story is being updated as more information emerges - please refresh the page for the most recent version.