Ashes, Ashes...

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:

• Volcanic bombs or volcanic blocks: debris greater than 64mm in diameter (2.5”)
• Lapilli: debris 2-64mm in diameter (.078 to 2.5”)
• Ash: debris particles less than 2mm in diameter (.078”)

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:

• Motors/Engines: internal combustion engines are prone to failure from volcanic ash due to the clogging of air filters; other parts can fail due to “sludge” forming between parts that need to move freely
• Paint Finishes: abrasive components of volcanic ash wear away finishes over time
• Electronics: items short-out due to dust particulates entering otherwise contained compartments; circuitry shorts-out
• Machinery: bearing, gears and any other movable parts that are not well-sealed are subject to damage and/or failure
• Power Sources: highly charged ash particles produce frequent electrical discharges causing damage from short circuiting
• Telecommunications: dust particles either scatter or absorbs radio signals preventing connections from occurring (think satellite TV, WiFi, FM-Radio, etc.)
• Roadways and runways become impassible: little to no visibility if dry, reduced visibility and extra slippery if wet
• Air filtration and water filtration systems fail: due to combination of ash clogging filters and affecting moving parts of system
• Building’s structural integrity fails: dry ash, 4” thick, weighs up to 200 pounds per square yard (twice as much when wet)

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.

• Tephra means "ash"
• Pyro means "fire"
• Klastos means "broken"

Properties of Volcanic Ash
​

• Hard Substance, Minute in Size
• Cannot be Dissolved
• Extremely Abrasive
• Corrosive
• Conducts Electricity When Wet
• Heavy
• Difficult to Clean Up

Originally posted in Headline Discoveries, Fall 2010