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Archive for the ‘Plate Tectonics’ Category


The headlines say it all: Iceland has crippled Europe. But, journalists aren’t referring to Iceland’s recent banking collapse. They’re talking about the eruption of the Eyjafjallajökull volcano in southern Iceland. The volcano began erupting quietly late last month. However, a particularly violent series of eruptions began earlier this, melting parts of a glacier at the top of the mountain. Approximately 800 local residents had to be evacuated as the eruption continued, shooting volcanic ash high into the atmosphere.

That’s where the “crippling” effect began. The ash, suspended high in the atmosphere, was blown southeast by an unusual wind pattern. What lies southeast of Iceland? Well, mostly the expansive waters of the North Atlantic Ocean, until you reach Europe. Unfortunately, the volcanic ash blowing at an altitude that planes like to occupy.  Volcanic ash can tear and gum up the works of airplane mechanics, causing engines to stall.  Thus, as the ash cloud spread across northern Europe, airports were shut down: the British Isles, Scandinavia, and on down into central and eastern Europe. As London ends its second day with all airports closed, the demands for railway tickets are skyrocketing. So is the ash cloud.  Eyjafjallajökull is still erupting, and those unusual southeastern winds continue to blow the ash to Europe.  European airports may be shut for several more days.

While news outlets are covering how the ash cloud has spread, how passengers are coping, and how airlines are suffering, I thought it might be nice to bring up a seldom-discussed topic: why Iceland has so many volcanoes. Iceland is a relatively small island in the north Atlantic. No other landmasses in that region harbor volcanoes. Greenland, the nearby sleeping giant, is frozen and inert. Northern Europe is devoid of volcanic activity. So, what’s the matter with Iceland? Why does it have volcanoes? Why is it even there?
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My earlier post bemoaning the Pacific Northwest’s lack of preparation for a megathrust-style earthquake led to a long description of the basics of plate tectonics. Revisit that post to remind yourself how Earth’s tectonic plates move, sliding past one another, moving apart, or colliding head on. Over our short lives, we see only a tiny bit of evidence of this awesome process. But, over the hundreds of millions of years that life has been thriving on this planet, the face of Earth has changed dramatically.
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Geologists and engineers in the Pacific Northwest are analyzing the damage and devastation in Chile from their recent earthquake, and they don’t like what they’re seeing. An op-ed in this weekend’s New York Times argues that the Pacific Northwest population centers, and the Puget Sound metropolitan region in particular, are entirely unprepared to face future earthquakes and associated hazards. Their evidence? American building and infrastructure codes, and the unique example of Chile: a developed country prone to similar types of earthquakes seen in the Pacific Northwest.
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The geologic processes that shape Earth’s interior and exterior seem to crawl along at a snail’s pace, at least from the perspective of a single life. Sure, in the scope of the planet’s 4.6 billion year existence, Earth has changed quite a bit. But, for the handful of decades we can collect observations, we may be lucky to collect some observations: erosion of a hillside, extension of a glacier, or shift in a river’s channel. For us, we still often have to wait decades to see Earth’s evolution in action.

However, sometimes these processes occur quickly. Rather than waiting decades, drastic changes can occur in a year, a month, or even the blink of an eye. The violent eruption of Mt. St. Helens on 18 May 1980 changed the mountain and the surrounding landscape in a single day. My biochemistry professor in college remembers how her parents had to climb up onto the roof of her house near Tacoma, Washington to push away the ash that was piling up after the eruption.

The recent earthquake in Chile shows us two examples of the big and small changes (by human standards) that geologic events can bring. For the huge change: the city of Concepcion (the closest major urban area to the earthquake) moved a full 10 feet to the west due to the release of energy and the violent shaking that accompanied it. Other cities moved smaller distances (the Argentine capital moved less than a foot), but 10 feet is a pretty significant move by human standards. For the small change: a day on Earth is now 1.26 microseconds shorter.

The recent earthquakes in Chile and Haiti made me wonder about other geologic events that have shaped our environment in the blink of an eye. Earthquakes? Volcanic eruptions? Erosion? Those are the primary examples I could come up with. But, there’s one more category I can think of: volcanic births. An eruption? Yes. But, a very special type of eruption: the eruptive activity that gives birth to a brand new volcano.
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