Mark is one of the OU's internationally renowned band of vulcanologists. He has spent time on some 15 active volcanoes in the course of his PhD research into developing methods of remote sensing - monitoring volcanic activity from a safe distance. These include two stints on the devastated Caribbean island of Montserrat.
The OU has one of the foremost vulcanology departments in the country, but it's a field that had attracted little popular attention in the UK, until the dramatic eruption of the Soufriere Hills volcano on Montserrat in 1995.
Millions of TV viewers saw Mark at work in a Channel 4 documentary about the vulcanologists monitoring the Montserrat eruption. Mark's role involved getting as close as 30 metres from the active core, taking measurements to help predict the volcano's future behaviour - work on which many lives may depend.
Hell on earth is a good description of the working environment. The volcano's core is spewing out avalanches of hot ash that are at 800 degrees centigrade and move at up to 50 metres a second. Even the air surrounding these flows is lethally hot for a distance of about 10 metres. The scientists always work in pairs, wearing anti-flammable suits, breathing apparatus and hard hats.
One of Mark's tasks on Montserrat was to measure the noxious gases being given off. "If you imagine taking a Coke bottle, shaking it up and then undoing the top, it fizzes out. An eruption is like this. The more gases we are monitoring, the more potentially explosive it is," he explains. Another job was to measure the seismic activity accompanying eruptions. "This information will tell us if it is building up to a peak," he says.
With volcanoes prediction, not prevention, is the name of the game. "Vulcanologists are trying to predict what is going to happen, which way the flows will go and where the damage will be. No matter how good our technology, we will never be able to stop a volcano."
It's this awesome power which draws Mark towards volcanoes, despite the real danger. "It is a calculated risk. We have a helicopter to get us out, and we are relatively experienced."
But fatalities do occur, as the OU knows only too well. OU researcher Professor Geoff Brown and nine colleagues died in an eruption on Mount Galeras, Colombia, in 1993. According to Mark, it was reckoned to be relatively safe.
"Trying to `second guess' a volcano is not an exact science, it's more like a game of Cluedo - something politicians, who decide on evacuation, have trouble understanding," says Mark.
"Our main aim is that no one gets killed, but this means crying `wolf' quite often. On Montserrat we were able to say what area everyone should be evacuated from, but it was 18 months before anything happened." The predictions were finally confirmed on 25 June last year, when an eruption killed about 30 people who were still inside the evacuation zone. If it hadn't been for the warning, the death toll would have been far higher.
Criticism of scientists on Montserrat is based on misunderstanding, Mark says. "Our role is to advise the administrators; it is up to them to convey the information to the public." And administrators have to take into account the practicalities, and the politics, of the situation.
But there have been problems, which were all too apparent to scientists on the spot. "People were evacuated and put into church halls, maybe 200 with their beds just centimetres apart, and they were like that for 18 months. I sometimes found it difficult to keep my emotions in check."
What does the future hold for Montserrat? "This type of eruption could go on for years," Mark says. "And even if stopped tomorrow there will still be 65 million cubic metres of lava up there, hot and unstable. It will not be safe for a long time."
Should the whole island be evacuated? "It's not up to me, but, in my personal view, if people have grown up in an area, it is very difficult just to move away. Perhaps money should be ploughed into developing the north of the island, still relatively safe."
He's just returned from Michigan in the US, where he was invited to investigate the feasibility of using an American satellite to monitor the growth of volcanic ash clouds over Montserrat. Ash clouds are a serious hazard to aircraft, capable of stalling their engines; they caused more than $200m (pounds 121m) of damage in 1994 alone. Unfortunately on Montserrat, a humid island, the ash is often hidden from ground observers by ordinary weather clouds. Mark's investigations have shown that satellite monitoring could be used, not only to detect the clouds but to predict their movement. "But it will cost pounds 2m to buy the satellite equipment."
Tall and photogenic, with a soft Welsh lilt in his voice (his home is in Swansea), Mark has a natural affinity with the media. Following his appearance on Channel 4's Montserrat series, he's been screen-tested as a possible presenter and asked to write series for a couple of TV companies on his favourite theme, natural disasters.
There seems to be an insatiable public appetite for TV footage of floods, wildfires, earthquakes, tidal waves, meteorite impacts and tornadoes, but does it really indicate anything more than a taste for sensation? People do love a good disaster, Mark agrees, but he feels it's important to be reminded of the awesome power of nature which, particularly in Britain, it's all too easy to forget.
"We are wrapped up in cotton wool in this country. We don't realise how lucky we are. Perhaps if people see what other parts of the world have to put up with, they will appreciate life here more," he says.
But not even Britain is immune from natural forces. "As we have seen, we do get floods and storms - remember 1987? - and there is always a chance we could get a major earthquake." In Britain? "You never know."
"Witnessing natural phenomena has an effect on the psyche - you are bound to start looking and reflecting on nature in a different way." And one of those areas of reflection could be on what humans are doing to the environment. "Popocatapetl in Mexico was chucking out tens of thousands of tons of sulphur dioxide a day into the atmosphere, so you might say, what does it matter what we do? But the point is, the planet has been coping with these natural phenomena and maintaining a status quo for a long time. Our contribution could just be the straw that breaks the camel's back."
In France, where Mark studied for his first degree in vulcanology, there is a lot more popular interest in the natural sciences. "People like Kraft in vulcanology and Jacques Cousteau in oceanography are national figures. The closest we have in Britain is Patrick Moore. It would be nice if other people could do for natural disasters what he did for stargazing."
But for Mark himself, the likelihood of working as a vulcanologist in Britain once his PhD is completed is slim, so meagre is the available funding. "With my qualifications I could get a job in the oil or the mining industry. But that doesn't really appeal to me. I would rather be doing what I'm doing now."Reuse content