Friday, July 26, 2013

Fun Friday Facts #80: Volcanic Eruptions

Volcanic eruptions are measured using the Volcanic Explosivity Index, or VEI, which was developed in 1982 by Stephen Self of the University of Hawaii and Chris Newhall of the US Geological Survey. The scale generally runs from 0 to 8, with 0 being a non-explosive eruption and 8 being the biggest eruptions in history. I get the impression there could be bigger eruptions than that, but we might be too dead to measure them.


I’m not even joking. The last VEI 8 eruption was the Oruanui eruption, which happened 26,500 years ago, and created Lake Taupo, the largest lake by surface area in New Zealand (with a surface area of 238 square miles or 616 square kilometers). The last one before that was the Toba event, which occurred between 69,000 and 77,000 years ago and is believed to have caused a volcanic winter up to 10 years long and 1,000 years of global climate change. It has also been linked to a genetic bottleneck in human evolution, which occurred about 70,000 years ago when the human population of the entire world dwindled to between 3,000 and 15,000 people. This could explain why there’s so little genetic diversity among humans today. Or, you know, it could all be bullshit. Those scientists, always kiddin’ around.

The Krakatoa eruption of 1883 was a VEI 6, and emitted six cubic miles (25 cubic kilometers) of...ashes and stuff. In case you’re not familiar with that one, it’s the one that blew up a whole island in Indonesia. Oh, wait, I just checked Wikipedia and it turns out it was only two-thirds of the island. That’s another thing my mother lied about.

The eruption killed 36,417 people (that seems like an awfully specific number, don’t you think?) and was heard 3,000 miles (4,800 km) away. Also, it was before cameras were invented, but not to worry, there was a sketch artist on the scene:


My mother also used to talk a lot about the Mount Saint Helens eruption of May 1980, which is odd because she wasn’t there, and also I’m starting to think my mother has an unhealthy obsession with things that explode. A 5 on the VEI scale, Mount Saint Helens had lain dormant for more than 100 years before a late March earthquake caused it to start venting steam. By late April, the mountain had “grown into a bloated, trembling blister of rock and magma” in the fascinatingly grotesque words of an unnamed Discovery News writer. Shit, I hope they’re paying you well, kid.

When “the blister popped” on 18 May 1980, the entire north face of the mountain collapsed into what would be the largest avalanche of debris in recorded history. The pyroclastic flow would flatten everything within 230 square miles (600 square km). Ash spewed forth from the volcano for over nine hours, reaching a heights of up to 16 miles (27 km) and raining down as far east as Edmonton, Alberta, Canada.


The explosion of Huaynaputina (don’t ask me how to pronounce that) in Peru in 1600 sent lahars (volcanic mudflows) 75 miles (120 km) away into the Pacific Ocean and may have caused some of the coldest global temperatures in 500 years. In fact, this VEI 6 explosion may have been responsible for the Russian famine of 1601-1603 that saw the ouster of the reigning Tsar. What we do know is that the sketch artist on this scene really should have been fired:

WTF is this? Where's the kablooie?