Monday, May 30, 2011

What's it like during an ash fall?

What's it like during an ash fall?

When ash begins to fall during daylight hours, the sky will turn increasingly hazy and "dusty" and sometimes a pale yellow color. The falling volcanic ash may become so dense that daylight turns to murky gray or even an "intense blackness" such that "it is impossible to see your hand when held up close to the eye." Loud thunder and lightning and the strong smell of sulfur often occurs during an ash fall. Furthermore, rain may accompany the volcanic ash and turn the tiny particles into a slurry of slippery mud. Most people also describe an intense quietness, except for thunder that may accompany the ash fall, giving a "deadness" to the normal sounds of life.

Volcanic Ash falls vary widely in intensity, size of the ash particles, and the degree to which light from the sun is obscured or blocked completely. Because of the unexpected darkness during daylight hours, loud thunder and lightning, and the sometimes strong smell of sulfur during a volcanic ash fall, many people describe the experience as eerie and frightening, disorienting and confusing, or dreadful. In extreme ash fall, for example when ash thickness is more than 5-10 cm (2-4 in), people may feel stunned and fearful of the conditions, have a difficult time breathing if a well-sealed shelter is not available. If caught outside during low visibility, people may become lost or extremely disoriented.

If heavy volcanic ash fall continues for 12-60 hours or more, roofs may collapse under the weight of the ash, resulting in more confusion, injuries, and even death.

Knowing what to expect during and after an ash fall can help people (1) reduce their anxiety and uncertainty when ash is falling to the ground; and (2) prepare their families and communities to deal with the ash effectively.

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