Thursday, March 17, 2011

A tsunami in the Bristol Channel: How safe are Britain's nuclear power stations?

Last August I wrote:
In truth, the economic arguments against nuclear power were always stronger than the safety ones.
But events in Japan make that seem a little overconfident.

Ah, you say, that is in Japan. We don't have tsunami in Britain.

But perhaps we do. A few years ago I watched a television documentary which suggested that a flood that took place in the Bristol Channel in 1607 may have been caused by a tsunami.

With commendable honesty, a Burnham-on-Sea tourism website has a page discussing the theory:
The flood occurred around 9am on the '20th January 1606', although in the modern calendar this is the 30th January 1607. The event is recorded on plaques in a number of churches, including those at Kingston Seymour in Somerset, and in Monmouthshire at Goldcliff, St. Brides, Redwick and Peterstone.

The Kingston Seymour plaque reads: "An inundation of the sea water by overflowing and breaking down the Sea banks; happened in this Parish of Kingstone-Seamore, and many others adjoining; by reason whereof many Persons were drown'd and much Cattle and Goods, were lost: the water in the Church was five feet high and the greatest part lay on the ground about ten days."
As to what could have caused it:
A possible cause of the proposed tsunami is not yet known, but the possibilities include a landslide off the continental shelf between Ireland and Cornwall, or an earthquake along an active fault system in the sea south of Ireland.

This fault system has apparently experienced an earthquake greater than magnitude 4 on the Richter scale within the last 20 years, so the chance of a bigger tsunami earthquake is a possibility. It may also have been a combination, in that an earthquake might have triggered a submarine slide.
Maybe the Hinkley Point and Oldbury-on-Severn nuclear stations should not have been built?


dreamingspire said...

If you read all the way through the Wikipedia entry for 'Bristol Channel floods, 1607', you will see that the other possible cause, a storm surge, is also there. The Severn bore happens regularly, and is not a tsunami.

Jonathan said...

Nowhere do I mention the Severn Bore, let alone say it a tsunami.

Edis said...

The point is that the shape of the Mor Hafern (Severn Sea) is of a funnel and any excepional surge will be magnified. Whether thsi is technicallya tsunamor another water event.

There is a distinct threat of a major Atlantic tsunami triggered by a known unstable ledge in (I think) the Canary Islands. There was a Horizon programme about this a decade or so ago.

Simon Titley said...

The Canary Islands tsunami risk does not seem to be that great, according to this:
and this:

dreamingspire said...

Jonathan, think of Lord Bonkers' ear trumpet: it concentrates energy. So does the Bristol Channel (as those of us with Somerset ancestry have to call it - we would not use a Welsh name). More energy, bigger wave - can come from more than one source: different orphans might shout up at different times.

Anonymous said...

Take a look at this website;

A Tsunami is a wall of water caused by an earthquake and we have had them in the UK in the past, though very rarely. We will therefore in probability have them again, it's just a case of when. A Tidal Wave is caused by the tides/ storm surges.