Sir, - I write to correct a misapprehension that might have arisen from a short report in your edition of August 30th by your Science Correspondent, Dick Ahlstrom, and to offer some reassurance to potential visitors to the Canary Islands who might have been put off their visit by the article or by recent television coverage.
Dick Ahlstrom was quite properly quoting some research being carried out on the potential generation of a huge tsunami, or tidal wave, which could be generated by the collapse of an erupting island volcano dumping millions of tons of rock into the sea - a tidal wave which, it was suggested, could devastate the eastern coasts of North America and even cause significant coastal damage in Europe and Africa.
The research in question was the subject of a TV Channel 4 item which echoed a previous report on the BBC's Horizon programme. Unfortunately, the protagonists of this study have taken the accurate but alarmist view that such a catastrophic event is a real possibility, without adequately qualifying their prediction by examining the probability of its occurrence in the foreseeable future.
It is widely recognised that the frequency of natural disasters is generally related to their magnitude - put simply, "the larger the fewer".
Big volcanic eruptions in steep-sided volcanoes which have naturally unstable flanks are liable to generate landslips, but such eruptions do not occur very frequently and the slips are not necessarily very large.
The active volcano on La Palma, the island in question, has erupted several times in the past 500 years, and there have been several small landslips, but none has been disastrous. There is no indication that foreseeable eruptions will be any more dangerous.
It is true that there are the remains of several major landslips on the seabed around the Canary Islands, and clearly very large events have happened in the past, but fewer than a dozen seem to have occurred over the past 10 million years or so. Not a very high frequency.
In the past decade there have been quite a number of other island volcano eruptions - Montserrat, to name but one - but none have generated cataclysmic tidal waves.
All in all, the probability is slight; one of the authors of the research put it at the same level as a major asteroid impact on Earth, and I believe it is verging on scaremongering to publicise the frightful possibility without indicating the remote likelihood of its occurrence.
To holidaymakers, my advice would be to take your holiday in the sun - La Palma is a delightful island, it has mountains and beaches and fine weather, and I'm off there myself quite soon. - Yours, etc.,
Prof Chris Stillman, Geology Department, Trinity College, Dublin 2.