A magnitude 7.3 earthquake struck the Kermadec Islands region near New Zealand on Monday, the United States Geological Survey (USGS) said.
The quake was at a depth of 10 kms (6.21 miles). It was followed by a magnitude 5.4 aftershock 20 minutes later.
The U.S. Tsunami Warning System said there is a tsunami threat following the initial earthquake.
New Zealand's National Emergency Management Agency (NEMA) said it's assessing whether there is a tsunami risk but urged anyone near the coast who felt "a long or strong quake" to get to the nearest high ground immediately.
"We are assessing whether the M7.3 KERMADEC ISLANDS REGION earthquake has created a tsunami that could affect New Zealand. Anyone near the coast who felt a LONG or STRONG quake should MOVE IMMEDIATELY to the nearest high ground, or as far inland as you can," NEMA said
The agency said people should be self-evacuating immediately from all places near the coast where the earthquake was felt either for longer than a minute or was strong enough that it was hard to stand.
On its website NEMA said people should not return until the all clear message is given by Civil Defence.
"Walk, run or cycle if at all possible to reduce the chances of getting stuck in traffic congestion.
"If a tsunami has been generated, the first wave may not be the most significant. Tsunami activity will continue for several hours and the threat is real until this warning is cancelled."
People in coastal areas should:
- Follow the "long OR strong, get gone" guidance above
- Listen to the radio and/or TV for updates, and NZCivilDefence Twitter and Facebook
- Listen to local Civil Defence authorities
- Stay out of the water (sea, rivers and estuaries, this includes boats)
- Stay off beaches and shore areas
- Do not go sightseeing
- Share this information with family, neighbours and friends