Deadly Volcanoes, An Ash Cloud and a Helicopter

Ancient civilizations thought the wrath of gods had been invoked when a volcano erupted.  Today, our scientists are intrigued by the complex nature of these powerful giants.

Iceland is again in the news because of volcanic eruptions.  This time it is the turn of Grimsvotn.  In 2010, it’s unpronounceable cousin, Eyjafjallajokull, spewed ash and debris into the atmosphere causing European airports to close, grounding planes for days and causing widespread concern for those suffering from asthma and breathing problems in Western Europe. 

Grimsvotn started to erupt on May 21st – this is the largest eruption it has experienced for 100 years.  The ash cloud that rises above this volcano reached 12 miles into the sky and settled at an altitude of between 10-15 miles by May 22nd.

Amazing video of lightning, within Grimsvotn’s volcanic ash plume, has been captured by Jon Gustafsson for



No-one is too sure why volcanoes produce or attract lightning.  Some scientists think it may be due to the friction caused by ash and debris particles ‘bumping’ into one another and becoming electrically charged

Whatever the reason, I’m sure you’ll agree it’s a spectacular sight!  … and a rather dangerous place to fly a helicopter!!

Five Deadly Volcanoes:

  1. Deadly volcanoes include Krakatoa – the tsunami that followed this massive eruption in 1883 killed around 36,000 people.
  2. Vesuvius exploded in AD79 and buried Pompeii and Herculaneum which killed around 16,000
  3. In 1902, Mount Pelee, on the island of Martinique, destroyed everything in it’s path and around 30,000 island inhabitants.
  4. Geologists measure the strength of a volcanic eruption using the Volcano Explosivity Index (VEI) which measure the amount of material released in an explosion.  Mount St. Helens scored 5 out of 8 (a cubic kilometer of material was released when it exploded.)
  5. About 73,000 years ago, a volcano called Toba is thought to have been the largest volcanic eruption.  Expelling over 1,000 cubic kilometers of debris it scored a VEI maximum of 8.  It created a crater (caldera) that was 100km long and 30 kilometers wide.  The effects of this explosion plunged Earth into a world wide ice age.

The one to watch, though, is the super-volcano that sits within Yellowstone National Park in Wyoming. 

Scientists have begun to get concerned at the rate that it’s been rising; 3 inches a year for the last 3 years.  However, despite their concern they have to admit that they don’t really know what they’re dealing with.  The last time it erupted was over 600,000 years ago and when it next explodes it could be with a force a thousand times more powerful than the Mount St. Helens eruption and would leave two thirds of the U.S. uninhabitable. 

But it’s only had 3 major eruptions in the last 2.1 million years.  Even the smaller eruptions happened over 70,000 years ago.  So, it may be beyond our lifetime, or that of our grandchildren, before it stirs again.







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