Iceland Volcano: The Big Picture

Yes the Iceland volcano - called Eyjafjallajökull - is dramatic, but it is mainly an inconvenience.

But as the Christian Science Monitor notes:

Every time in recorded history that Eyjafjallajökull volcano has erupted, the much larger Katla volcano has also erupted.

How much larger? Katla's eruptions are around 10 times stronger than those of Eyjafjallajökull.

As AP notes:

The two volcanos are side by side in southern Iceland, about 12 miles (20 kilometers) apart and thought to be connected by a network of magma channels.

Katla usually erupts every 40-80 years. The last major eruption occurred in 1918, although there may have been a small eruption that did not break the ice cover in 1955.

So Katla is overdue.

But - as MSNBC points out - the big threat is the nearby Laki volcano:

Iceland's Laki volcano erupted in 1783, freeing gases that turned into smog. The smog floated across the Jet Stream, changing weather patterns. Many died from gas poisoning in the British Isles. Crop production fell in western Europe. Famine spread. Some even linked the eruption, which helped fuel famine, to the French Revolution. Painters in the 18th century illustrated fiery sunsets in their works.

The winter of 1784 was also one of the longest and coldest on record in North America. New England reported a record stretch of below-zero temperatures and New Jersey reported record snow accumulation. The Mississippi River also reportedly froze in New Orleans.

That eruption is considered the largest lava flow in modern times.

Laki and Katla are in the same volcanic system. On the following map courtesy of Google maps, A is Laki B is Katla:

So the bottom line is that if it's just Eyjafjallajökul, it will be an inconvenience. If Katla also blows - there's no indication that it will, but that situation could quickly change - then things will get much more intense.

But if Laki blows, we may be in for some crop failures, gas pollution, and a cold snap. Luckily, there is no reason to worry at this point about Laki.