Volcanic eruptions, meteors, war, pestilence, death, famine, etc.

Factual Questions
1

“The fourth angel sounded his trumpet, and a third of the sun was struck, a third of the moon, and a third of the stars, so that a third of them turned dark. A third of the day was without light, and also a third of the night.”
-Revelation 8:12, NIV

As I’m sure you guessed by the subject line, I’m reading the “Left Behind” series, by Tim LaHaye and Jerry Jenkins. In studying Revelations, I tried to translate what I could into natural events (natural defined as conforming to the laws of physics). Just a mind game, of sorts. While engaged in this, a hypothetical question occurred to me about one possible case, and I became fascinated with not only the answer, but in how it might be obtained. Getting there’s half the fun, I guess. My question:

If we assume that the above verse in Revelation refers to a literal event, and if we assume that this reduction by 1/3 of incoming celestial illumination is caused by an increase in dust in the atmosphere, how many average volcanic eruptions would it take to throw that much dust into the atmosphere? This question assumes that there is such a thing as an average volcanic eruption.

As a secondary question, what size meteoric impact would it take to toss that much dust into the atmosphere?

I realize, of course, that this could all be symbolism, or that the decrease in light reaching earth could be done supernaturally, or even by a significant number of small asteroids entering our atmosphere and burning up before impact. However, I thought the answer itself might be interesting, and as I’ve already e-mailed this to Cecil, I figured I’d post it here, too.

Ideas?

2

It is all symbolism.

However, to go along with the game:

1816 was known as “The Year Without Summer” because of the dust and the resulting cold produced by the eruption of Mt. Tamboura in the Dutch East Indies. Another eruption in the late 1800’s (Krakatoa in 1883?) led to another series of very cold summers and frightful winters. Mt. Pinatubo played havoc with our weather just a few years ago.

You might look up sites dealing with those eruptions to get estimates of the amount of light blocked by the dust.

(Use http://www.google.com/ to search on the individual volcanoes or on vulcanism or “volcanoes atmosphere”.)

3

As for comet/asteroid impacts, I assume you’re looking for something large enough to cause a global change. A size of about 1.7 km (1 mile) is where you start seeing some global effects such as climate changes due to the dust thrown into the atmosphere (frequency of such an impact is about once every 250,000 years).

The K/T event (that killed the dinosaurs et al.) occurs about once every 100 million years. This was from a 10 km object (6 miles wide).

source: “Report of the Task Force on potentially hazardous Near Earth Objects”, United Kingdom, Sept 2000