Southshore residents get 10-minute escape
CHARLIE GATES Last updated 05:00 26/03/2012

Southshore residents should go upstairs or stand on a high sand dune in the rare event of a tsunami generated by an earthquake off Christchurch, experts say.

Scientists calculate the chances of a tsunami being generated by a quake in Canterbury over the next year is less than 1 per cent. A quake would need to be at least of magnitude 7.0 and centred offshore to trigger a tsunami.

Environment Canterbury (ECan) hazard analyst Helen Grant said the worst-case scenario would involve a wave that was two metres above sea level. It could be 3m high if it was high tide.

The wave would take between five and 10 minutes to reach shore in the worst-case scenario.

Residents in the Christchurch beach suburb of Southshore would not have time to flee. They would need to be at least 4m above sea level, GNS Science and ECan say.

"Bearing in mind a tsunami is very unlikely, if it did happen you would have 10 minutes before it arrived. You are not getting out of Southshore in 10 minutes," Grant said.

"People need to look at their own circumstances. If they can go up to another storey or if they are near a high sand dune, then that is good."

In the event of a large quake, the general advice is to get at least two blocks from any waterfront, or if that is not possible, to get to 4m above sea level.
Copied from The Press

Copied from the Book Julius von Haast
Lyttelton has had a tsunami and witnessed and reported on by Julius von Haast in 1868.
About  3.30 am on Saturday August 15th 1868 the tide was at half ebb the water suddenly receded from the harbour at a rate of about 12knots.  Boats were left on their side.   A the end of the breakwater where the average depth of the water was 15 feet one could walk dry shod.  About 4.30am with a roar like thunder a wave of about 8 foot high rushed up the harbour with great speed surging round the vessels, tearing them from their wharves and snapping their warps like twines and played havoc with the shipping.  At 4.50am the water was within 3 feet of the railway level, having risen 25 feet perpendicularly in 20 mins.

-