Less than 8 enough for me

A109 Light Utility Helicopter flight with mayor Gisborne City from the air in November 2023.

Opinion

Civil Defence is copping flak from various readers of The Herald for a lack of timely tsunami alerts following the big old shake. I think they have a point but not the one I would make.

Tsunamis are only generated by exceedingly large earthquakes of 8 or so on the Richter scale. Smaller, shallower and closer ones may produce strange currents but not life-threatening waves.

For comparison, the Boxing Day 2004 and the Tohuku 2011 quakes were at least 9.1 Richter, or 100 times as powerful as the 2.30am one we experienced. And 10 times the Kermadec event.

Belated warnings proved farcical when my phone klaxon went off at 5.30 telling us not to worry. Calming words on getting back to sleep were less forthcoming.

It took GeoNet almost no time to establish and present the earthquake size, depth, and placement on its site. At a then estimated 7.3, it posed no risk of a dangerous tsunami, and at that point Civil Defence should be telling almost everybody not to be concerned, comfort your loved ones and go back to sleep.

The Kermadec quake induced a new level of panic, and complicated the picture further. Here is a quake that is actually capable of generating a tsunami, but is 1500km away and therefore plenty of time to present an accurate risk assessment and evacuation plan.

The breathless coverage we saw and heard is far more likely to produce anxiety and fear that is disproportionate to the danger, and ultimately have people wondering if the little boy is crying wolf. Civil Defence should have a system in place to present all this information as effectively as GeoNet. How is it they apparently do not?

Of course, all earthquakes will have different responses but broad-brush understanding in the community appears to be limited and Civil Defence education should focus a lot more on understanding risk than evacuating for a real event, the part most people fully grasp.

“Long, strong, be gone” is useful in the absence of the internet, but GeoNet saying it's less than 8 is enough for me.

Donald Robson