How does all of this discussion tie in with Brighton revitalization?

As you have probably noticed, none of the Pegasus Bay beach suburbs has any structures approaching a useful ‘tsunami refuge’ height (probably at least 20 metres).

And as part of the revitalization (arguably the first, most important step) high-density residential apartment development is seen as part of the vision.

The buildings themselves are likely to be apartment towers, built as standard commercial structures, using load-bearing columns to support large floor plates. This is a very robust, well understood construction technique, and has a couple of great advantages for Near Tsunami protection.

Firstly, provided the lower storeys are designed with either no walls or walls which will ‘pop out’ under wave pressure, the structure can act just like a bridge. The supporting columns present little area for the waves to attack, and the water flows harmlessly through the first and possibly second storeys.

Secondly, if sufficient clear floor space on plates above the expected tsunami level is available for public refuge, those spaces become the escape route and refuge for a significant number of local residents. Such floor space can accommodate a surprising number of people: if you’ve ever looked at an elevator’s certificate of fitness and wondered how they can get all those people in, well, in a tsunami you could pack a refuge space to that sort of density.

Developers have to provide a ‘reserve contribution’ as part of the development’s contribution to open public reserve space. The suggestion here is quite straightforward:

i) require developers of multi-storey towers to provide accessible refuge space for x people above a designated height, in lieu of or as part of the Reserve Contribution.
ii) Require pop-out walls up to a designated tsunami height, and design the building itself in conformance to tsunami robustness standards.

The refuge space does not add to development costs, as that contribution has to happen anyway whether in cash or provision. It does require that physical space be set aside – but this could be as simple as an extra-wide stairwell. In any case, such details are for the engineers and planners to sort through: we are concerned here just with the broad principles.

So to summarise what citizens can be told in Civil Defence advice, once these refuges are available:

in a Near Tsunami, run to the nearest designated Refuge Tower and climb as high as possible.

In a Distant Tsunami alert, follow the Civil Defence instructions in the back of the Yellow Pages.