Gem Trails of Washington Book

I like old mountains, really old mountains. Today (July 24) is my wife's birthday and we decided to go to Leesburg, Virginia to a restaurant that we both like to celebrate that birthday. When we had gotten about 15 miles, reaching Centreville, Virginia, we could see the foothills of the Blue Ridge Mountains in the distance. Some of these mountains used to be volcanoes hundreds of millions of years ago.

Greg Breining, in his book Super Volcano: The Ticking Time Bomb Beneath Yellowstone Naitonal Park,, has written a book that will or should scare you if you live close to certain volcanoes. There are actually some volcanoes that are just magnificent but not scary. Mauna Loa, the largest volcano on earth also has the greatest lava flow, but that flow is smooth and predictable and really isn't very scary at all. And then there are volcanoes which aren't super volcanoes, but which are very dangerous. The most dangerous volcano is probably Mt.Vesuvius. Vesuvius has a million people living within four miles of the crater. About 3 million could die in the first two hours of a major eruption. Put simply, and Breining says this, people haven't learned the lesson of Pompeii. But Breining wants us to understand the so-called super volcanoes are ones that are nothing like Mauna Loa or Vesuvius.

There are super volcanoes in Indonesia like Krakatoa (which killed 36,000 people in 1883) or Tambora which exploded in April 1815 and filled the upper atmosphere with gases and ash so that North America and Europe experienced "The Year without a Summer" in 1816. And then there is Yellowstone, the volcano that is a sleeping giant underneath Yellowstone National Park. When it goes off the next time, it could kill tens or even hundreds of millions of people.

Here are a few facts about this particular super volcano. The last time it went off, with a huge explosion of ash and lava, was 70,000 years ago. So maybe we shouldn't worry about it. But it is an active volcano and the magma is known to be building under the surface of Yellowstone, slowly pushing upwards.

The timing of the eruptions actually may be of more concern. The last three were 2.1 million years, 1.3 million years, and 640,000 years ago. That eruption 70,000 years was only a major eruption and not a super eruption. And the frequency between  super eruptions seems to be shrinking. We may be overdue for a super eruption.

Why does Yellowstone volcano explode as it does? Breining does a good job of explaining this. It is because the earth's crust where it Yellowstone is located'in the middle of the North Ameircan plate--does not flow as it does in Hawaii. It is rhyolite, filled with silica. Unlike in Hawaii, where molten basaltic magma easily flows up as lava, in Yellowstone, the rhyolite traps the magma … and the pressure grows and grows. And then it blows. A volume of magma expands 670 times as it rises from the mantle through the crust. And so you get the explosion.

The hot spot under Yellowstone first led to a caldera-causing eruption about 17 million years ago in what is now northwestern Nevada. Over 16.5 million years, the hot spot has moved 350 miles to the northeast and has caused at least 142 Yellowstone-scale eruptions. There were many more eruptions at first, more than 30 every million years at first and they have slowed to about three every million years. As the North American tectonic plate slowly moves, the location of the eruptions from this hot spot has changed. It has left a long track of calderas, some of which are 30 miles wide across the whole Snake River basin. The one 2.1 million years ago had a caldera that was 30 miles by 50 miles and ejected 600 cubic miles of magma.

Volcanoes tend to be where oceanic plates subduct beneath continental plates. Hence you get the famous Ring of Fire, the volcanoes around the Pacific Rim and the hot spots that give rise to volcanoes. There are more than 100 hot spots like the one under Yellowstone that power volcanoes and also move the tectonic plates around the surface of the earth. There are different theories about why a hot spot like the one under Yellowstone occurs in the middle of a continental plate and not at the edge. Most of the super volcanoes are located in Western North America, western South America, and Indonesia. But they have appeared elsewhere as well like Texas ... and in Wyoming.

The last major super volcano on earth occurred 26,000 years in New Zealand creating Lake Taupo. New Zealand at the time was uninhabited. An eruption today there would kill more than 200,000 people. This is minor compared to what would happen if a super eruption from the Yellowstone volcano occurred.

If Yellowstone had a super eruption, all of Wyoming would be gone. The Great Plains wheat fields and much of the Corn Belt would be buried under ash for one or more growing seasons, and field reclamation might take decades or even generations. Rivers will be filled with sediment. Machines will have major problems because of the ashes. Put simply, a billion people could die, and nations will fall.

When will a Yellowstone super eruption occur? We simply don't know. It could be in a hundred years or in 10,000 years. But it is coming.

Am I worried? Well, I would visit Yellowstone National Park as a tourist. I think that the risks to you are greater from an angry grizzly bear or stumbling into a hot pool than dying from a super eruption. But it does bother me that a super eruption does seem to be overdue and we know that that the next eruption is definitely coming whether it is in ten years or 10,000 years. So yes, I would visit Yellowstone as a tourist, but I wouldn't live next to Mt. Vesuvius.

The book itself is well written and the science of volcanoes and super volcanoes are well explained. I do think it could have used some better editing. There is some repetition of facts, but maybe that was intentional to drive these facts home. I'm glad that I read it.

Like I said at the beginning, I like old mountains. The Blue Ridge mountains are part of the Appalachians and, at one billion years of age, are the oldest mountain range on earth. When they were young they were the tallest mountains on earth and had a number of very active volcanoes. The mountains now are worn down and the volcanoes are all extinct. I like it like that. Extinct volcanoes are a lot safer to live close to.