A Kiwi volcanologist studying in Europe has found himself in the middle of one of the most disruptive eruptions in recent memory.
GNS scientist David Johnston is stranded in London after attending a disaster planning meeting with 25 other scientists.
The eruption of the Eyjafjallajokull volcano in Iceland has caused a massive ash cloud to drift across Europe, and led to thousands of flight cancellations in and out of the continent. Dr Johnston had to endure a 33-hour overland journey from Paris to get to the meeting because of the flight groundings, and his return home is also on hold.
"This is what we study, so to be part of it is interesting," Dr Johnston said.
Travelling with renowned British volcanologist Steve Sparks, Dr Johnston said the pair had joined an exodus from France, catching a car ferry to England which normally caters for 25 passengers a day but which carried 700 in this case.
"It was like people fleeing Europe from 60 years ago. It was quite a scene, really ... Everyone's sharing their stories about their exodus and where they'd come from."
Volcanologists and disaster planners had long speculated about the impact of an eruption in Iceland, believing its effect would be significant, but the research had garnered little attention, he said.
The Eyjafjallajokull eruption was relatively small but a "perfect storm" of weather conditions - a high over Europe, which was also downwind from Iceland - meant the ash cloud didn't disperse and blanketed the entire continent.
"Had the weather been normal, strong westerlies or whatever, you wouldn't have had this."
The Eyjafjallajokull eruption had shown how interconnected the world is, and how vulnerable supply chains are to air travel disruptions.
"It does really illustrate how interconnected our society has become and how we are dependent on certain lifelines for functioning."
Booked to fly home tomorrow, with airspace opening up suggesting he might be able to do so, Dr Johnston said the event had prompted research in to safe limits for when planes could fly.
While there was a lack of hard science to guide the decisions, he believed the ash concentration was sufficient to justify the closures.
Airlines have claimed that test flights show it is safe to fly. It is estimated airlines have lost more than US$1 billion (NZ$1.4 billion) after five days of closures and pressure has gone on European governments to open the airways.
"I'm not an atmospheric physicist or an aircraft engineer but the two combined have suggested that it is appropriate not to fly so one would follow that advice. They're not saying that lightly."
Dr Johnston said flights were now largely dependent on weather conditions. Planes could possibly fly even if the volcano continued to erupt, as long as the weather dispersed the ash cloud, rather than letting it sit over top of Europe.
"The weather really is the key to what is happening."
NEW ZEALAND'S VOLCANIC HISTORY
New Zealand experienced similar issues, although on a smaller scale, when Mt Ruapehu erupted in 1995 and 1996.
The eruptions threw out 60 million cubic metres of acidic ash, blanketing areas up to 300km from the volcano, with plumes reaching 10km into the air.
Aviation authorities declared no-fly zones in the North Island, with about 11 airports forced to close as well as State Highway 1 on several occasions.
The ash also caused millions of dollars of damage to hydro-electric turbines and electricity transmission facilities in the central North Island. Crops were damaged and livestock killed.
GNS volcanology section manager Gill Jolly said New Zealand had learned valuable lessons and had good monitoring systems in place.