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Archive for the ‘Geology’ Category


Tropical Storm Agatha pounded Central America over the past few days. The storm is blamed for 180 deaths, and caused widespread flooding.

An hour after a clothing factory in Guatemala City closed on Saturday, the building’s security guard left the empty factory to tend to his flooded house. Shortly after he left, the entire factory disappeared into the sinkhole pictured above. The sinkhole also claimed an intersection, and sent nearby residents fleeing for fear that the ground would soon disappear beneath their feet.

The sinkhole is 66 feet in diameter, and at least 100 feet deep. It’s sudden appearance, coupled with the it’s “perfect” circular shape have made some geologists hypothesize that a previously unknown cave formation is to blame. However, in 2007 a similar sinkhole consumed several homes and killed three people a mere three miles from this new formation. That sinkhole was ultimately blamed on heavy rains coupled with the city’s flawed drainage system. Geologists will certainly take the city’s drainage system into account as they investigate the causes of this new sinkhole.

In the meantime, law enforcement officers are keeping curious onlookers away from the sinkhole, as geologists prepare to descend the Earth’s newest opening and see what’s going on. Tread lightly.

Image provided courtesy of Paulo Raquec and the Guatemalan government.

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The image above shows Mount Saint Helens in Washington State as it appeared on 17 May 1980, thirty years and one day ago. A day after this photograph was taken, Mount Saint Helens erupted. The north face of the mountain exploded outward with the force of about 500 atomic bombs, killing 57 people and eradicating over 200 square miles of forest. It was the largest landslide in recorded history, and the Mount Saint Helens ash cloud circled the globe. Coming back from a helicopter survey of the destruction after the eruption, Washington State Governor Dixy Lee Ray could only say, “I feel like I’ve just come back from the moon.”

In 1982, President Ronald Reagan established the Mount Saint Helens National Volcanic Monument to preserve the eruption site. The centerpiece is Johnston Ridge, where a small visitor center was constructed. Johnston Ridge looks literally into the collapsed north face of the volcano. It is named for volcanologist Dr. David A. Johnston, who died in the blast and had made his observation post on that ridge.

In the years since the 1980 eruption, slowly but surely, life has returning to the volcano’s surroundings. Microbes, plants, and animals have once again made homes in the area the volcano devastated a mere three decades ago.

Below, for comparison, is an image of what Mount Saint Helens looked like four months after the volcano erupted, in September of 1980. It is taken from roughly the same position as the pre-eruption image above.
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Oil without the Drill

Oil is that precious substance which, for better or worse, we have quite an addiction to. We spend billions of dollars and risk (and occasionally sacrifice) lives to retrieve it from Earth’s depths. Yet, Earth is often not so greedy. The planet regularly releases crude oil on its own, with no help from us. The extent to which oil “seeps” up on its own is not known. However, scientists have recently uncovered a new tool to help them understand this phenomenon.
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The California Geological Survey turns 150 this year. As part of that celebration, they have released new maps revealing the state’s complex geology. One map in particular is making headlines: a map of all the known fault lines in California, including those discovered since the last fault map was put together in 1994. This fault activity map color codes fault lines based on their most recent activity. For the record, the faults in red and orange are the most active cracks to fret over.

In geology, a “fault” can refer to almost any break in a chunk of rock, as long as movement or displacement periodically occurs along that fracture. The many tectonic plates that make up Earth’s surface (go here to learn more) move past one another and collide along zones of complex fault lines, where the slow movement of the plates has caused fracturing of rock on both sides of the boundary. California is a textbook example of such a zone of fault lines. While most of the state resides on the massive North American Plate, a significant chunk (including all of coastal California south of the Bay Area) actually resides on the equally massive Pacific Plate. At California, the North American and Pacific plates are sliding past one another. The North American plate is moving south and east relative to the Pacific Plate’s north and west course. This plate boundary also extends further south, where past movements have torn lower California (the Mexican states of Baja California and Baja California Sur) away from the mainland, opening up the Gulf of California. However, plate boundary is at its most geologically troublesome as it runs through the American State of California.

The Pacific plate is on the left, while the North American plate is on the right. Image provided courtesy of the United States Geological Survey.
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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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While my mother fills out postcards in our hotel room on the Oregon Coast, I’m taking a few minutes to enjoy our hotel’s free internet access, and therefore violating my earlier statement that I won’t post anything new until next week. When skimming the science news just a few minutes ago, I stumbled on the latest geological news from the planet Venus, and just had to share.

Venus is a rocky planet similar in size to Earth. But, the similarities pretty much end there. It’s covered with a thick, toxic atmosphere that keeps the surface pressure over 90 times what we experience here on Earth. I won’t even get into the sulfuric acid clouds and the stifling surface temperatures. Venus doesn’t even rotate on its axis in the same direction that Earth does. There, the sun rises in the west and sets in the east. To top things off, a day on Venus lasts longer than a year on Venus.

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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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