Still not ready for tsunami
The response to yesterday’s tsunami threat suggests there’s more work to do to get the country quake-ready. Roads were gridlocked as residents on the east coast of the North Island fled for higher ground after a cluster of quakes up to 8.1 magnitude northeast of New Zealand.
Scientists said that, on average, a magnitude 8 or larger earthquake only occurs once a year anywhere in theworld, so thiswas a significant one and at a depth and magnitude to potentially generate a tsunami. There was a risk of strong aftershocks.
In Auckland, some people ignored a mobile emergency alert and went into the water. In Canterbury, Civil Defence asked people to stay away from beaches, river mouths, harbours and estuaries amid reports people were in the water and walking along beaches.
Perhaps it’s reflective of a growing fatigue with public health messaging after a year of grappling with Covid-19. But the mixed response indicates more education is needed. According to disaster research experts, New Zealand’s policy framework in relation to tsunamis has been sporadic, mainly triggered by large international tsunami events. The government initiated an extensive review of national preparedness after the 2004 Indian Ocean tsunami. It ranked the risk to property potentially on par with that of an earthquake and the risk to life even greater.
The 2004 tsunami was caused by a 9.3-magnitude earthquake that raised a 1200-kilometre stretch of sea floor by several metres, displacing an enormous volume of water, which surged inland in some places as much as several kilometres. New Zealand Civil Defence officials subsequently developed guidance for signs, evacuation zones, and warnings. GNS Science has produced guidance on how to incorporate tsunami modelling into land-use planning.
But experts say there’s a long way to go to ensure adequate awareness and preparedness of individuals and communities.
Some of New Zealand’s tsunami warning systems are ageing and ineffective. Forecasting also isn’t an exact science. It’s hard to work out precisely when waves may reach the shore, or how big they’ll be.
Because tsunami risks are hard to gauge, Civil Defence advice is never towait for an official warning: evacuate immediately on a tremor lasting longer than one minute, or one strong enough tomake it difficult to stand or walk.
In Whangarei yesterday, Shane Reti, deputy leader of the National Party, told RNZ he received calls from residents saying it was taking 30 to 40 minutes to get to higher ground across town, in what would normally be a five-minute journey. It might have been wiser to walk, as some council staff later did.
Our coastal communities have experienced significant growth in recent years. Some councils already consider tsunami risk in future urban planning. It would be prudent for others to follow suit.
Fortunately, by early afternoon, the largest waves had passed. But the initial warnings were widespread, with strong currents and unpredictable surges forecast from Northland to Wellington, and from Farewell Spit to Stewart Island.
A Colmar Brunton report last year on New Zealand’s earthquake readiness found 86 per cent of people had taken at least one action, but only 24 per cent had fully prepared their home for a big quake. Perhaps yesterday’s tremor is the jolt the country needed.