Warning: Keep away from the sea
Civil Defence is warning people to keep away from all Canterbury beaches and river mouths until early Saturday morning following the 8.3 magnitude earthquake in Chile.
The tsunami risk is not expected to be significant for Christchurch and Banks Peninsula, with experts predicting waves of up to 40cm overnight Thursday and into Friday.
However, people have been warned to stay away from all beaches and river mouths in the region for 24 hours after the first waves arrive.
Christchurch Civil Defence and Emergency Management (CDEM) manager Murray Sinclair said the tsunami risk was not significant for the region, but residents and boaties should still take care.
‘‘The Chilean earthquake is likely to create some waves in and around Christchurch, particularly in the harbours of Banks Peninsula where the water is likely to be choppy for up to 24 hours after the waves arrive just after midnight tonight. Water currents are also likely to be affected so people should stay away from the coast and waters.
The Ministry of Civil Defence & Emergency Management on Thursday issued issued a tsunami warning for Chatham Islands and all of New Zealand’s east coast.
Sinclair said any rising water was not expected to come onto land.
‘‘But the activity near the water’s edge would be a bit more turbulent, a bit stronger so the advice is, people, don’t go into the water.’’
Major Chilean earthquakes have affected Banks Peninsula previously. A magnitude 8.8 quake on February 27, 2010 created a series of waves and tidal surges that affected parts of New Zealand’s east coast the following day.
At their peak, late on the afternoon of February 28, seawater flooded the head of Lyttelton Harbour. Earlier in the afternoon, around midday and low tide, the sea receded from the harbour, leaving large areas of mudflats exposed.
The Lyttelton Port tide gauge for the day showed the remarkable comings and goings of the sea as a result of what happened about 9000km away. The tides were still wobbling wildly from the effects of the quake more than a day later.
The last tsunami to significantly affect the Canterbury coastline was in 1960 and was generated by a magnitude-9.5 earthquake off the coast of Chile. It caused fluctuations of up to 4.5 metres above normal sea level along the coast but its impact was minimal as it arrived at low tide.
Tsunami risks prompted South New Brighton School to buy 400 lifejackets for staff and students in 2012. School principal John Bockett said at the time the precaution was similar to ‘‘life jackets and flotation devices in airplanes – it’s just in case’’. ‘‘We are dealing with lots of precious wee lives and even though the chance of having a localised tsunami is very slim, it is important for us to be prepared,’’ he said.
The advice is, people, don’t go into the water.
Murray Sinclair Christchurch Civil Defence and Emergency Management manager