The science of cartography has come a long way over the centuries, from the caricatured coastlines of antiquity to the highly-detailed satellite images of today. We know our terrestrial boundaries very well, and until all the polar ice melts and raises sea levels, mapmakers are busy looking elsewhere. Greg Laden explores the magma chamber beneath Yellowstone, which was modelled by observing the transmission of shock waves through the earth’s crust. Greg explains, “This sonar-like approach allows the mapping of underground three-dimensional structure,” and he has the pictures to prove it. On Starts With a Bang, Ethan Siegel marvels at a new map of the moon created by the Lunar Reconaissance Orbiter, wherein each linear pixel equates to only 145 meters. If you get lost exploring the lunar wastes, don’t panic, just refresh your browser window and start again.
Erik Klemetti on Eruptions solicits your suggestions for the titular honor:
2009 is almost over and it has been quite a busy year, volcanically speaking. This is not to say that is was anomalously volcanic – more that many of the volcanic events captured the media’s attention. I’ll be putting together a “Volcanic Year in Review” for 2009 and at the end I’ll award the 2009 “Volcanic Event of the Year” (a Pliny?) … but now its your turn to nominate events for the award.
Suitable entries include “eruptions, signs of an eruption, a big research article, a media debacle/success” or just about anything else volcano-related. Don’t miss your chance to nominate!
When it comes to geologic phenomena, the difference between renewal and cataclysm can walk a fine line. On All of My Faults Are Stress Related, Kim Hannula elucidates the distinction between causes and triggers. Citing an article about the Zipingpu Dam that concludes that the weight of the reservoir might have triggered an earthquake, Hannula notes that “the ultimate cause of the earthquake was the collision of India with Asia, and the resultant tectonic mess.” Elsewhere, Erik Klemetti on Eruptions dresses down Popular Science alarmism, concluding that the chance of exploratory drilling causing a “game-ending eruption” in the Campei Flegrei is minimal. In another post, Klemetti reports that the Mayon volcano in the Philippines may be “headed towards a significant eruption,” with evacuation of nearby villages already underway.
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As the Earth’s tectonic plates shift and grind miles below our feet, we feel the effects on the surface in the form of earthquakes and volcanic activity. As Ed Yong of Not Exactly Rocket Science and Chris Rowan of Highly Allochthonous explain, earthquakes far from tectonic plate boundaries may be aftershocks of more violent seismic events along mid-continental faults that occurred hundreds of years earlier. According to a study published in Nature this week, faults in the middle of a continent take much longer—100 years or more—to return to normal activity; thus, aftershocks can occur long after what would be expected from coastal quakes. In other earthquake news, Chris Rowan also reports on Iran’s decision to move their capital city to a less earthquake-prone location than Tehran. And on Eruptions, Erik Klemetti gets to the bottom of a recent Slashdot post proclaiming that recent volcanic activity in Ethiopia is causing the African continent to rift apart, forming a new ocean. In fact, explains Erik, the recent eruptions are part of a known process. “This is nothing new,” says Erik. “We’ve known that Africa is splitting apart for decades.”
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