Wave heights can be expected for the entire New Zealand coast. Image/supplied
UPDATE 2pm: The tsunami threat has passed - although unusual water conditions are still likely as a result of the Chilean earthquake.
The tsunami marine and beach threat issued by the Ministry of Civil Defence and Emergency Management yesterday in response to the tsunami generated by the earthquake near Chile has now been cancelled.
The threat to New Zealand's East Coast and the Chatham Islands has now largely passed.
However, advice from the GeoNet Tsunami Expert Panel is that there will be some unusual water conditions such as local tidal surges and strong currents for the next 24-36 hours.
This unusual activity will gradually return to normal conditions during this time. People should exercise caution and discretion before entering the water or going out in small boats.
UPDATE 10.25am: Late waves from the Chilean earthquake should be arriving in the next few hours, the Ministry of Civil Defence and Emergency Management says.
Wave heights so far have fit well to those modelled, the Ministry said.
The Tsunami Experts Panel expected there would be late arriving waves reflected from Pacific Islands which should be arriving at the Chatham Islands and the East Coast over the next few hours.
In the February 2010 tsunami these were the largest waves recorded.
The Ministry said to expect unusually strong currents and unpredictable water flows near the shore.
This means a threat to beach, harbour, estuary and small boat activities.
The severity of currents and changing water flows will vary within a particular coastal area and over the period this warning is in effect.
Current assessments indicate that coastal inundation (flooding of land areas near the shore) is not expected but this assessment may change.
Tsunami activity will continue for several hours and the threat must be regarded as real until this warning is cancelled.
UPDATE 7.15am: Bay of Plenty Civil Defence has reported minor fluctuations in wave height along the coast.
Waves of up to 30cm have been observed at several tsunami gauges along the coast but the Chatham Islands have experienced the most significant activity with wave heights reaching 0.5m.
The Ministry of Civil Defence and Emergency Management reported this morning that the first tsunami wave following the earthquake in Chile reached New Zealand at 11.50pm at the Chatham Islands.
In the Chatham Islands, waves of around 50cm were experienced in places, repeated ebbing and flowing of the tide, along with ocean noises associated with tide surge.
A few families in who live two-to-three metres off shore self-evacuated.
Minor fluctuations in sea-level have been recorded in North Cape, Great Barrier Island, Tauranga, East Cape, Gisborne, Napier, Castlepoint, Wellington, Kaikoura, Christchurch. These have been estimated to be no more than 30 cm.
The wave heights have been within those anticipated by the Tsunami Expert Panel.
Unusual marine and coastal activity can be expected for around 24 hours after the first wave. There could be continued unpredictable activity, ebbing and flowing and strong currents.
The national warning remains in place.
UPDATE: Bay of Plenty Civil Defence is urging people in coastal areas of the Bay of Plenty to keep away from beaches, coastal areas and river mouths in the coming 24 hours.
Clinton Naude, Bay of Plenty Civil Defence Group Controller said that it was likely there will be tidal surges and unsettled seas tonight and throughout the day tomorrow.
"We recommend that people stay out of the water and away from coastal areas. Whitebaiters should take extra care too - they may not be fishing on the coast but tidal surges could create unusual currents and rising water levels in the lower reaches of our local waterways," Mr Naude said.
People in the affected coastal areas should:
• Stay out of the water (sea, rivers and estuaries, including boating activities)
• Stay off beaches and shore areas
• Do not go sightseeing
• Share this information with family, neighbours and friends
• Listen to the radio and/or TV for updates
• Follow instructions of local civil defence authorities
UPDATE: The tsunami warning has been further issued for most of the country's east coast.
The Ministry of Civil Defence & Emergency Management (MCDEM) has issued a tsunami warning (marine and beach threat) for Chatham Islands and East Coast New Zealand.
Wave heights between 0.2-1m can be expected for much of the East Coast and the entire New Zealand coast.
The northern region of Chatham Islands will most likely experience wave heights in the higher portion of the 0.2m-1m band.
The tsunami warning will remain in effect until a cancellation message is issued by MCDEM.
EARLIER: A tsunami warning (marine and beach threat) has been issued for the Coromandel, East Cape, Chatham Islands and Banks Peninsula following a powerful magnitude-8.3 earthquake which shook Chile's capital Santiago.
The expected arrival times are 12 hours for Chatham Island and 13 hours for the East Coast of New Zealand (after the earthquake at 22:54 UTC).
The BOP Civil Defence Emergency Management Group say strong tidal currents are likely to go on for 24 hours, with a peak 4 to 10 hours after the first arrival.
BOP Civil Defence say they expect unusually strong currents and unpredictable water flows near the shore.
This means a threat to beach, harbour, estuary and small boat activities.
People in the affected coastal areas should:
1. Stay out of the water (sea, rivers and estuaries, including boating activities)
2. Stay off beaches and shore areas
3. Do not go sightseeing
4. Share this information with family, neighbours and friends
5. Listen to the radio and/or TV for updates
6. Follow instructions of local civil defence authorities
Visit www.bopcivildefence.govt.nz for further information throughout the day.