 Because of recent activity in Iceland, there have been many news reports done on volcano eruptions and the damages that can be caused by volcanic ash. So, just what is “volcanic ash?
THE ASSUMPTION It’s not what most people may envision. Typically, when most people think about ash, they picture something light and fluffy—like ashes in the fireplace or barbecue. So, when they hear that a volcano has erupted and everything is covered in ash, the natural assumption is that it is relatively harmless and can be easily swept away. Not true. THE BLAST AND ITS COMPONENTS Volcanic eruptions occur when gases in magma, or molten rock, expand and escape into the air. They also occur when water that is super-heated by magma abruptly flashes into steam, or when thermal contraction from chilling occurs after contacting water. Each scenario leads to eruptions that occur with explosive force, causing escaping gases to shatter surrounding rock layers of the Earth. When eruptions occur in areas covered by glaciers, the resulting plume can contain glass-rich deposits that were created when melted ice quickly chilled lava prior to its explosion. Material expelled from the volcano at this point is called ‘”tephra.” To better study components of a volcanic eruption, scientists have broken tephra into classifications based on size:
PERSPECTIVE While the size of a volcanic bomb doesn’t seem so large, some perspective is needed. Take, for example, a storm producing hailstones of roughly the same size. They can cause excessive damage to car windshields and even slate roofs. To a person struck by a volcanic bomb, the impact would feel something like getting hit with a baseball thrown by a major league pitcher due to the high rate of propulsion. Volcanic bombs and lapilli do cause problems but, because they settle to the ground at a much quicker rate than ash, the extent of their damage is often not as far reaching. The tiny size of ash and its ability to readily travel everywhere means it can be a lot less apparent to ascertain the damages it can cause. THE REALITY Much has been written about the damage to people, animals, air, soil and water, but less so the damage and chaos that ash can cause to other things, especially those that are technologically and/or mechanically based. Following are just a few things that could be heavily impacted:
These examples show that volcanic ash is dramatically more devastating than it appears and has a great potential to leech its way into so many things that are important to the day-to-day operation of life for everyone in areas affected by volcanic eruptions. Getting to the Bottom of It The words "tephra" and "pyroclast" both derive from the Greek language.
Properties of Volcanic Ash
Originally posted in Headline Discoveries, Fall 2010 |
