Warning of tidal surges

Tsunami waves of up to a metre are expected to hit the east coast of the North and South islands, as well as Stewart and the Chatham Islands, today following the large earthquake off Chile.

The Ministry of Civil Defence & Emergency Management said people in affected areas should stay out of the water, away from shore areas, and not go sightseeing.

A Coromandel school, misreading the timing of the warning, evacuated yesterday.

The ministry said modelling suggested wave heights up to 1m.

In the northern Chathams wave heights were likely to be toward the higher end of the band. In the other areas heights were likely to be toward the lower end.

Unusually strong currents and unpredictable water flows near the shore could be expected in the affected areas, the ministry said.

‘‘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.’’

Mercury Bay Area School, in Whitianga, Coromandel, notified parents on the school’s Facebook page that all students had been evacuated.

It is believed the school was acting on information from the national warning system, which stated the tsunami threat in UTC (coordinated universal time), not NZ time, Waikato Civil Defence Controller Lee Hazelwood said. ‘‘That is the assumption. ‘‘They have got the national warning, which is 12 hours out – and thought: we need to get out.’’

The Gisborne District Council said people were being advised to stay out of the water and off beaches and wharves. ‘‘The first tsunami waves or tidal surges may reach East Cape just after midnight [overnight]. People need to stay out of the sea, rivers and estuaries and not to go sightseeing.

‘‘We advise residents to be aware that the largest expected wave is not always the first to arrive. Waves can continue for several hours and often can get larger during this time.’’

The Hawke’s Bay Regional Council said whitebaiters and divers were likely to be the most at risk. A wall of water was not expected but the tsunami effect could be a turbulent 20 to 30cm.

The first wave of many was expected after 1am today and would likely carry on throughout the day.

A coastal navigation warning for the New Zealand eastern coastline, including the Chathams, said vessels already at sea should remain well offshore and at depths of 100m or more until otherwise advised.