National tsunami alert downgraded

The tsunami warning in place for New Zealand has been downgraded to an advisory by Civil Defence.

The Pacific Tsunami Warning Centre had cancelled the warning for New Zealand, following last night's 8.8 magnitude earthquake near Chile.

However, based on scientific advice there was "still a likelihood of surges and rapid sea level changes to continue for up to 24 hours after the initial wave arrivals" and an advisory would remain in place, the Ministry of Civil Defence & Emergency Management said.

The Chatham Islands and Banks Peninsula near Christchurch, could still see waves between 1 to 3 metres, and waves of up to 1 metre could still hit the east coasts of the North and South Islands, which posed a threat to people in boats, on beaches and in coastal communities.

Waves generated by the massive earthquake in Chile at 7.35pm yesterday (NZT) were approximately one metre high at the Chatham Islands, 0.3 metres at East Cape, Napier, Castlepoint, Tauranga and North Cape, and 0.4 metres in Gisborne.

It was important to note that these are the first arrivals and larger waves may follow over the next 6 to 12 hours, Civil Defence said.

"There may also be strong surges and rapid rises in sea level in some places. The situation continues to be closely monitored."

On the Chatham Islands, residents have seen big changes in water level. Chatham Islanders took to what little high ground there is, after warnings that a major earthquake in Chile overnight had generated a tsunami.

Bernadette Malinson, of Flower Pot Bay, on Pitt Island in the Chathams, reported significant surges this morning which emptied the bay and revealed the full height of the piles on the wharf there.

"The bay empties right out. It takes about a minute and a half and then it surges back in, in about the same amount of time," she told Radio New Zealand. "The surges have been getting bigger -- at least 2m at present."

The tidal activity, which had been going on all morning, had not caused any damage, she said. In Akaroa, on Canterbury's Banks Peninsula, tidal surges of up to 30m were reported.

In the space of 10 minutes, the water receded almost to the swimming pontoon off the main beach in the township and then returned quickly, one witness said. Just as in Pitt Island, the pier in Akaroa was fully exposed. The Pacific Tsunami Warning Centre (PTWC) issued a tsunami warning in response to the Chile earthquake.

A tsunami was generated, with wave measuring 2.34m was measured at Talcahuano, Chile and 0.35m at Easter Island, Chile.

Specialists said a threat to beachs and small boats existed for the east coasts of the North and South Island, as far around as Puysegur Point on the Southland west coast, and north to Cape Reinga and extending south to Ahipara, on the Far North west coast.

Sea levels along the Gisborne coast had dropped dramatically, prompting authorities to close roads to beaches and clear away sightseers.

Waikanae Beach Holiday Park manager Diane Ross said the sea suddenly receded about 9.20am. It was almost high tide when the water pulled out to below the low tide mark.

It dropped about one-1.5 metres in a matter of moments, Ms Ross told Radio New Zealand. The water went "very, very brown", indicating that it was being stirred up by swirling currents, she said. All the holidaymakers at the campground had been evacuated early this morning and were watching the action from a marae at nearby Kaiti Hill.