Richard Moore: Flaws feared in tsunami escape plan

The bridge to Nowhere

So, if Papamoa and the Mount are hit by a massive tsunami then all we need do is react quickly and we will survive.

As soon as we feel a strong tremor - one that knocks us off our feet or lasts about a minute - then we need to grab emergency stuff and hightail it to higher ground inland.

That's the prediction from Tauranga City Council's emergency management spokesman Paul Baunton.

Baunton reckons we would survive a 14m tsunami if we head on foot over the Wairakei Stream and if we did so: "Once people have crossed that barrier, the likelihood is that they will just get wet, with a high survival rate."

As you would expect of a sceptical journalist reading those words I decided to check out the various factors of his claim - upon which the lives of tens of thousands of people will depend.

So first up I called a tsunami expert, Dr Willem de Lange from Waikato University.

Now I only had a brief chat with him - he wasn't there when I phoned him again for more detail - but here is the key thing.

Dr De Lange said it was possible to survive a 14m tsunami at Papamoa because the height of our sand dunes would reduce the size and power of the wall of water hitting us.

For example, 12m dunes would reduce a 14m tsunami to about two metres of water.

Okay, thought I, he's the expert, so wherever we have 12m dunes the people and homes behind have much more chance of survival.

Dr De Lange did say, though, that anyone caught in the open by the remaining water would be in trouble, and even those sheltering in houses would not necessarily be safe.

What depth of water I asked?

He said 1m of water could knock wooden homes off their foundations, and in block homes - brick or concrete - while the walls would stand the waters would go through windows and doors.

Both are important to know.

So wherever on our coastal strip we have very large dunes - say 12m - then we are more protected from a 14m tsunami.

One place I know of with dunes that high is down Te Tumu way - the farthest end of Papamoa Beach Rd - where we have, for now, not that many homes. Where I live our dunes are about four to five metres.

That means a 14m tsunami will come over the top of them at about the height of street lights.

To me, that is still a big wall of water. And let's not forget it isn't a wave, but a racing block of power that could be a kilometre deep.

Anyway, picking up my camera bag I took a quick walk to the supposed safety of the Wairakei Stream.

The Bridge to Nowhere is about eight minutes walk from my house and so I'm feeling good as I approach it.

The span is about two metres wide and crosses the four-metre-wide stream before heading up a small rise of about five metres. It is an easy walk for an adult, unencumbered by kiddies or an old person, or those who don't move as well as me.

Okay, so I'm on the high point of the rise (5m) while most of the east-west slope is maybe 4m.

Looking back over the rooftops towards the beach I picture a 9m-10m wave trundling towards our position at about 70km/h. It would reach the ridge in less than a minute.

Rolling over homes and the distance it travels inland will no doubt lessen the wall's force, and the ridgeline will further reduce it, but it would still be a considerable danger.

By my quick calculations (original tsunami 14m, -5m for dunes, -1m for run inland, -5m for ridgeline) that potentially leaves a 2m to 3m wall of water to break over the high ground and flow on.

With Baunton's words in mind I turned around and looked at the countryside beyond the stream and the small ridge and was concerned at what I saw.

The land is rough and undulating and criss-crossed with wire fences. Progress across it would be very slow.

To me the land beyond the ridge would be a death trap in raging waters, even those only a metre deep.

And here is another worrying factor: what if the tsunami was to hit at night? There are no lights on the bridge and the area beyond is likely to be pitch black. People without torches would be stumbling around in the dark.

Mind you, if a 14m tsunami struck at night the death toll in the suburb would be horrendous.

Now you can guarantee there will be an official response to this column claiming I am scaremongering and everything is all right and well in hand.

All I am going to say is check it out for yourself.

How high are your dunes? How far is high ground away from your home? Can you get across the Wairakei Stream easily? What is on the other side of the high ground you are aiming for?

For while council continues to ignore our pleas for an exit road out of Papamoa East your only hope to escape a tsunami is by foot.

And if you don't think it is possible, make sure your local councillor is aware of it.

NB: I would love to hear from Papamoa school principals about their evacuation plans and any practices they have had.

Richard Moore is an award-winning Western Bay journalist and photographer.

Richard@richardmoore.com