*This article first appeared on RNZ and is republished with permission.
New Zealand could experience strong and unusual currents, and unpredictable surges at the shore after a magnitude 7.7 earthquake near New Caledonia.
The National Emergency Management Agency (NEMA) is warning that coastal areas in New Zealand could experience strong and unusual currents, and unpredictable surges at the shore after a magnitude 7.7 earthquake near New Caledonia.
In a national advisory, NEMA warns there is a danger to swimmers, surfers, people fishing, small boats and anyone in or near the water close to shore.
People in or near the sea from Ahipara Bay to the Bay of Islands, Great Barrier Island, and from Matata to Tolaga Bay should move out of the water, off beaches and shore areas and away from harbours, rivers and estuaries.
There is no need to evacuate other areas unless directly advised by local civil defence authorities, the advisory said.
NEMA advised the strong currents and surges may occur around North Cape from approximately 4.20am. This may be later and the first tsunami activity may not be the most significant.
Strong and unusual currents and unpredictable surges will continue for several hours and the threat must be regarded as real until the advisory is cancelled.
Advice for people in areas under threat:
- Move out of the water, off beaches and shore areas and away from harbours, rivers and estuaries
- Do not go to the coast to watch the unusual wave activity as there may be dangerous and unpredictable surges
- Listen to local civil defence authorities and follow any instructions
- Share this information with family, neighbours and friends
National Emergency Management Agency acting director Roger Ball said there was no threat to land for New Zealand, but strong currents and surges were expected in some northern areas of the country.
“In those parts of New Zealand we are asking people to stay out of the water and stay off the beaches because of the possibility of surges and unusual currents.
“We don’t expect any significant change to the current advisory unless there is a subsequent seismic event and we’re constantly keeping an eye out for that but we don’t have any information to indicate that at this time.”
NEMA issued estimates of the earliest wave arrival times, noting arrival times may be as much as one hour later:
- Auckland East 6.05am
- Auckland West 5.24am
- Lottin Point (East Cape) 4.59am
- Mount Maunganui 5.12am
- New Plymouth 6.04am
- North Cape 4.20am
- Port Tauranga 5.22am
- Whanganui 8am
- Whangārei 4.59am
GNS duty seismologist Dr John Ristau said there may be more earthquake activity in the South Pacific today, following the 7.7 quake.
“It’s most likely that this 7.7 is going to be the main shock,” he said. “However whenever you get an earthquake, particularly a large earthquake like this one, it does increase the risk for another large earthquake, even a bigger one, nearby.
“Even though that increased risk is still small, it’s a possibility.”
The subduction zone earthquake occurred at the boundary of the Australian plate as it pushes underneath the Pacific plate. “It wasn’t close to land areas … but it did generate a tsunami with a height of a few tens of centimetres,” Ristau said.
Geoscience Australia said the quake struck at 2.20am with an epicentre 401km east of Tadine, New Caledonia.
Seismic data indicated the undersea earthquake struck at a depth of 54km.
Australia confirmed a marine tsunami threat to Lord Howe Island, a marine reserve more than 700km northeast of Sydney, but said evacuations were not necessary.
The US Tsunami Warning System said waves reaching up to a level of 1 metre above the normal tide level were possible for some coastal areas of Vanuatu and Fiji, and a tsunami watch was in effect for American Samoa.
In this country, NEMA decides any official warning status for New Zealand.