It is raining when I emerge from the tunnel at South Kensington Tube in London. I gaze up at the gothic faade of the Natural History Museum, past the smirking pterodactyl gargoyles towards the spires of this Darwinian cathedral.
A dollop of water scores a direct hit on my eyeball and I blink down, regaining focus on an ant whose desperate struggle is breaking the surface tension of a puddle. Scooping the insect to safety, I reflect on humanity's proximity to disaster. We may start the day like this ant, only to be struck down by flood, fire, rocks from space or the cosmically insignificant trembling of our little planet.
This isn't a thought I have on a regular basis, but I'm here to meet Professor Bill McGuire, who will be delivering the museum's annual science lecture, a talk called 'Global Catastrophes: A Punter's Guide'. McGuire, Benfield Professor of Geophysical Hazards at University College London, will talk his audience through the question: 'Volcanic super-eruption, asteroid impact, mega-tsunami, cataclysmic earthquake... what's next?'
A friendly figure in a blue denim shirt and crumpled trousers, McGuire tells me how many people he keeps briefed on global geophysical events, or 'geegees'. There's the insurance folk in the City, the Government, the academics and the public " and 'taxi drivers always want to know about 'that mega-tsunami that's meant to wipe out New York".
In 2000, McGuire helped to make a BBC documentary about the Cumbre Vieja volcano on the island of La Palma, in the western Canary Islands, which could cause a land mass the size of the Isle of Man to tumble into the ocean, sending a wall of water racing across the Atlantic to devastate the east coast of the US. In his latest book, Surviving Armageddon: Solutions for a Threatened Planet, my interviewee describes the inevitable landslide as 'a Damoclean sword' poised over the North Atlantic.
Is he keeping an eye on it, then? He shrugs. 'By 2007,' he says, 'they will have this Atlantic tsunami warning system in place, based on four buoys down the East Coast and one stuck out in the Atlantic. But that's not going to give very much warning. If we monitor the Cumbre Vieja we might have a few days' notice, which would make a huge difference. We could get it done for about pounds 50,000 per year.'
That's not much, given the wealth of the vulnerable cities. 'You'd think so, wouldn't you?' says McGuire. He seems resigned to the fact that things move slowly in the natural hazard awareness business, if at all. 'I have to be resigned, don't I? Or I'd have a heart attack. I guess I use humour to cope.'
It was a bit of a fluke that McGuire, 50, became a vulcanologist. 'Initially I was drawn to astronomy, but my maths wasn't good enough. I wanted to do a planetary geology PhD but there was nothing around. Then the chance came up to map a large hole on Etna. It was too good to be true. Etna's the biggest volcano on the continental crust, nearly 11,000 feet tall.'
McGuire remembers the first time he looked out over the Valle del Bove. 'The cliffs were 1km high. There were scree slopes of ash at a 45-degree angle you had to run down; the whole thing moved with you. It was a bit disconcerting, but fantastic fun. I worked there for three years " horrendous!'
McGuire first witnessed the lethal potential of his specialisation in 1979. 'While we were there, nine tourists were killed near Bocca Nuova.' He is matter-of-fact about this, as he is about the number of his contemporaries who have died on volcanoes. 'Scientists can be the worst. They think they're immune. A group of us drafted a code about how to behave on a site, and then a few months later there these same guys were, peering down into the chasms... Actually, I thought I'd had it myself while observing the Montserrat eruption from a chopper in 1996. …