LOS ANGELES — The massive ash cloud from an Icelandic volcano is pretty much a run- of-the-mill ash cloud that is a concern primarily because of its location and the prevailing winds, experts said Thursday.
Except for the immediate vicinity of the volcano, the eruption is unlikely to produce any long-term climatic or health effects unless there is a sharp change in the amount of material emitted, researchers agreed.
Although researchers call the ejecta ash, it really is very fine-grained rock and glass, the bulk of it ranging from about a 12th of an inch in diameter down to 1/25,000th of an inch. Anything larger settles out of the air quickly in the immediate area of the volcano. But the finer material can reach the upper atmosphere and circulate for months.
Because the particles are formed by explosive stress fractures, they tend to be very sharp-edged. When humans and animals inhale them, they can harm air passages. When they are sucked in by a jet engine, they can shut it down.
The ash cloud can also block sunlight from reaching the Earth, leading to a temporary global cooling. But a more serious problem is produced by the sulfur dioxide emitted in most eruptions.
Los Angeles Times
