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Τελευταίες 5 Αναρτήσεις Paragliding And Aviation

Πέμπτη 19 Φεβρουαρίου 2009

Από τον σεισμό του Μαίου στην Ισλανδία:Two Icelandic pilots report vibrations, wind and hot air as the quake strikes

*Άρθρο του cross country magazine

An Icelandic pilot has revealed he was flying directly above the centre of an earthquake that struck the island back in May. Hans Kristján Gudmundsson, a paraglider and paramotor pilot with ten years’ experience, told Cross Country he felt the quake, which measured 6.1 on the Richter scale, when he was half a kilometre above the ground.“It was the most amazing experience of my life,” he said. “I felt the earthquake clearly at 500 m agl.” The quake struck near Selfoss, a popular tourist spot 50 km from the capital Reykjavik, on May 29 this year. Buildings were damaged and as many as 20 people were injured, according to press reports at the time.Hans said: “My friend Sigvaldi and I were thermalling in a mountain called Ingolfsfjall in south Iceland when the earthquake hit.

“At first I felt the wing start vibrating, this was something new to me, something I have never felt while flying. I thought maybe I had entered some strange air with fluctuating waves or something.“Then I heard the noise. It sounded like thunder coming from the ground. I looked down and I saw the whole mountain moving and sliding forward. I saw boulders the size of houses falling down.”It was then, he said, “I realised that this was an earthquake.”He added: “It was amazing being right over the source of the quake in a paraglider. What is the chance of that happening?”Realising what was happening, Hans grabbed his camera and took pictures, “to show the power of this natural disaster”.The earthquake and vibration lasted 20 seconds. “It turns out it was actually two earthquakes in one, and the source was right under my wing,” said Hans. “The wing felt like an instrument that the Earth was playing, such was the vibration.”The pair had been flying in thermic air close to the sea. “We were expecting the seabreeze to kick in any minute,” he said. “The air changed almost instantly. This huge mass of hot air was released at the same time as when the ground shook. We felt it a few minutes after the earthquake, then the seabreeze came in much more strongly than normally and I had a hard time penetrating. I ended up landing going slightly backwards.”Iceland, which has a population of about 300,000, sits on top of the mid-Atlantic ridge, a geologically unstable tectonic plate boundary. A spokesman for Iceland’s Institute of Earth Sciences said the country had been expecting further quakes after a series of tremors in the same area in 2000.Roger Musson of the British Geological Survey told Cross Country he had never heard of such an event before.He said: “I wouldn’t like to try and make a definitive statement about the mechanics, but the fastest form of earthquake waves are compressional waves akin to sound waves, known as P waves. Some P wave energy crosses over into the atmosphere to be perceived as sound. This is likely to be the explanation of the vibration and sound, though I’m surprised they were so perceptible at such an altitude. What Hans was seeing, of course, was a secondary effect of the earthquake (triggered landslides).“There is a certain amount of evidence that some of the overcoming of friction in earthquake faulting results in a release of heat, which is a possible explanation of the thermals immediately encountered.”It is thought that Hans’s and Sigvaldi’s experience is unique. A tracklog of their flight is online at

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