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Plate Tectonics and Continental Drift (Infographic)


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Plate Tectonics and Continental Drift (Infographic)

 

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A Dramatic 260 Foot Crater Has Mysteriously Appeared In Siberia


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A Dramatic 260 Foot Crater Has Mysteriously Appeared In Siberia

7/16/14 3:32pm

Russian geologists are on their way to a remote region of Siberia’s Yamal Peninsula to investigate the mysterious appearance of what looks like a gigantic Sarlac Pit. Opinions are divided as to what caused the apparent crater.

As the Siberian Times is reporting, the unexplained hole was spotted by a helicopter flying over the gas-rich region of the Yamal peninsula, a location that translates to the “end of the world.” Initial estimates place the width of the puncture at about 80 meters, but its depth is not known. A debris field around the perimeter suggests that the material was somehow thrown out of the crater.

An expedition to the crater has been organised by the Yamal authorities. The team includes two experts from the Centre for the Study of the Arctic and one from Cryosphere Institute of the Russian Academy of Sciences. They’re expected to arrive at the scene later today, at which time they’ll take samples of soil, air, and water.

According to the Siberian Times, initial reports and images were suspected to be fakes, but the new images taken by Russian engineer Konstantin Nikolaev suggests it’s very much real. The feature is thought to have formed about two years ago.

Scientist have posited a number of theories to explain the crater, though it’s not likely to have been caused by a meteorite impact, nor does it exhibit the features of a sinkhole. One website claims that it’s evidence “of the arrival of a UFO craft” to Earth. But there are at least two other — and far more plausible — explanations worth considering.

A Pingo

University of New South Wales polar scientist Chris Fogwill says it’s probably a geological phenomenon known as a collapsed pingo, or hydrolaccolith. As theSydney Morning Herald reports, a pingo is a block of ice that’s grown into a small hill in the frozen arctic ground:

The ice can eventually push through the earth and when it melts away it leaves an exposed crater. Dr Fogwill says the permafrost [frozen earth] can be hundreds of metres thick, allowing for large ice features.

“It’s just a remarkable land form.

“This is obviously a very extreme version of that, and if there’s been any interaction with the gas in the area, that is a question that could only be answered by going there,” Dr Fogwill said.

Fogwill says that global warming may cause more pingos in the future.

An Ignited Mixture

Another explanation has been posited by Anna Kurchatova from Russia’s Sub-Arctic Scientific Research Center. She believes the crater was formed by a water, salt, and gas mixture that ignited an underground explosion, also the result of global warming.

Kurchatova thinks that enough gas accumulated in ice mixed with sand beneath the surface, and that this was mixed with salt. And indeed, this area was immersed under the sea some 10,000 years ago. The change in climate caused an “alarming” melt in the permafrost, releasing gas akin to the popping of a champagne bottle cork.

Given that this region contains many gas pipelines, that’s a troubling conclusion.

Read more at the Siberian Times and the Sydney Morning Herald.

All images: Konstantin Nikolaev via Siberian Times

Follow me on Twitter: @dvorsky

Every US River Visualized in One Glorious Map


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Every US River Visualized in One Glorious Map

The Deadliest Volcano in the United States Just Got Really Weird


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The Deadliest Volcano in the United States Just Got Really Weird

A plume of steam and ash billowing out of Mt. Saint Helens in 1982, two years after the most destructive eruption in US history. Image: Wikimedia

Picture a volcanic eruption: fiery magma and smoke billowing skyward as a towering mountain empties its over-pressurized belly of a hot meal. At least, that’s how most of us think it works. So you can imagine volcanologists’ surprise when they discovered that Mount St. Helens, which was responsible for the deadliest eruption in US history, is actually cold inside.

Apparently, it’s stealing its fire from somewhere else.

Mount St. Helens is one of the most active volcanoes of the Cascade Arc, a string of eruptive mountains that runs parallel to the Cascadia subduction zone from northern California to British Columbia. It’s also one of the strangest. Most major volcanoes of the Cascade Arc sit neatly along a north-south line, where the wedging of the Juan de Fuca tectonic plate beneath the North American plate forces hot mantle material to rise. Mount St. Helens, however, lies to the west, in a geologically quiescent region called the forearc wedge.

“We don’t have a good explanation for why that’s the case,” said Steve Hansen, a geoscientist at the University of New Mexico in Albuquerque.

Image: US Geological Survey

Seeking answers, Hansen recently led a seismic mapping survey of Mount St. Helens. In the summer of 2014, his team deployed thousands of sensors to measure motion in the ground around the volcano. Then, they drilled nearly two dozen holes, packed the holes full of explosives, triggered a handful of minor quakes, and watched as seismic waves bounced around beneath the mountain. “We’re looking at what seismic energy propagates off in the subsurface,” Hansen explained. “It’s a bit like a CAT scan.”

Their analysis, which is published today in Nature Communications, appears to have created more questions than it answered. From seismic reflections, Hansen and his colleagues learned that the types of minerals present at the boundary between Earth’s crust and mantle are markedly different to the east and west of Mount St. Helens, confirming that this area is geologically special. But instead of finding a hot magma chamber directly beneath the volcano, seismic data indicates a relatively cool wedge of serpentine rock.

Not only is Mount St. Helens out of place, but it also lacks the magma reserves we’d expect given its violent history. So, where on Earth is Mount St. Helens getting its fuel?

Hansen suspects the volcano’s magma source lies to the east, closer to the rest of the Cascade Arc, where material in the upper mantle is hotter. But that still leaves the question of why gooey rock being forced westward, through the crust or upper mantle, to erupt in this one off-kilter location. Earthquakes in the deep crust may be partially responsible, but more data is needed to confirm such a link.

Fortunately, more data is exactly what Hansen, and other scientists associated with the Imaging Magma Under St Helens (iMUSH) project, are now collecting. What geologists learn about this weird volcano—how its magmas form, how they moved around, when and why they erupt—could improve our understanding of volcanic arc systems around the world.

“Mount St. Helens is pretty unusual,” Hansen said. “It’s telling us something about how the arc system is behaving, and we don’t yet know what that something is.”

[Nature Communications]

Maddie is a staff writer at Gizmodo

Plate Tectonics and Continental Drift (Infographic)


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Plate Tectonics and Continental Drift (Infographic)

Earthquake Faults Around San Francisco Are Dangerously Interconnected


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Earthquake Faults Around San Francisco Are Dangerously Interconnected

Yesterday 11:34am

 http://gizmodo.com/earthquake-faults-around-san-francisco-are-dangerously-1788069171#_ga=1.57756259.892298330.1450614712
San Francisco as seen from the ISS. (Image: NASA/Scott Kelly)

Geologists have discovered that two deadly faults beneath San Francisco—the Hayward and Rodgers Creek faults—may be linked. Should one slip, it could trigger the other fault to collapse as well, causing an earthquake even larger than the one that struck back in 1989.

Geologists are very familiar with the Hayward Fault and its potential to unleash devastation along the populated subdivisions just east of San Francisco, but a new paper published in Science Advances by researchers from the US Geological Survey shows that a less-appreciated neighbor to the north, the Rodgers Creek Fault, may be connected. The discovery of a “missing link” between the two faults could change the way city officials plan for the next big earthquake in the Bay area.

Scientists are quite certain that the next major earthquake to strike the region will probably result from a rupture in either the the Hayward or Rodgers Creek faults, but as the new research from USGS geologist Janet Watt and colleagues shows, these faults, which now appear to be interconnected, could rupture simultaneously. If that were to happen, it would produce a magnitude 7.4 quake along their combined 118 miles (190 km).

A quake of this strength would cause extensive damage and loss of life. And at a magnitude 7.4, such a quake would be five times stronger than the 6.9 Loma Prieta quake in 1989, which led to 63 deaths and nearly $10 billion in damages.

The Hayward Fault stretches from San Jose to San Pablo Bay, passing through Berkeley and Oakland. New research it extends far enough northwards to join with the Rodgers Creek fault. (Image: USGS)

Previous work suggested that the two faults were separated by a two-mile wide buffer under the bay. The Hayward Fault stretches for 62 miles (100 km) from San Jose to San Pablo Bay, passing through Berkeley and Oakland, while the Rodgers Creek Fault runs 56 miles (90 km) north of the bay through the heart of northern California.

Watt’s team used high-resolution subsurface imaging to visualize the Hayward fault as it runs under San Pablo Bay. To their surprise, they discovered a previously undetected strand of the fault that bends toward and connects with the Rodgers Creek fault. Using computer models, the researchers found that the stress patterns fit in perfectly with visual observations of fault deformation and seismic activity in the area.

Because they’re interconnected, these two faults basically act as one, making it considerably easier for an earthquake rupture at either the northern or southern portions of the two faults to continue straight on through.

[Science Advances]

George is a contributing editor at Gizmodo and io9.

Massive Earthquake Along the San Andreas Fault Is Disturbingly Imminent


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Massive Earthquake Along the San Andreas Fault Is Disturbingly Imminent

Friday 12:50pm

 http://gizmodo.com/massive-earthquake-on-the-san-andreas-fault-is-disturbi-1787279784
The USGS estimates a 1 in 100 chance of the San Andreas Fault rupturing between now and October 4. (Image: SanAndreasFault.org)

A series of quakes under the Salton Sea may be a signal that the San Andreas Fault is on the verge of buckling. For the next few days, the risk of a major earthquake along the fault is as high as 1 in 100. Which, holy crap.

The United States Geological Survey has been tracking a series of earthquakes near Bombay Beach, California. This “earthquake swarm” is happening under the Salton Sea, and over 140 events have been recorded since Monday September 26. The quakes range from 1.4 to 4.3 in magnitude, and are occurring at depths between 2.5 to 5.5 miles (4 to 9 km).

Quakes recorded under the Salton Sea on September 27, 2016. (Image: USGS)

For seismologists, these quakes could represent some seriously bad news. The swarm is located near a set of cross-faults that are connected to the southernmost end of the San Andreas Fault. Troublingly, some of these cross-faults could be adding stress to the San Andreas Fault when they shift and grind deep underground. Given this region’s history of major earthquakes, it’s got some people a bit nervous.

Calculations show that from now until October 4, the chance of a magnitude 7 or greater earthquake happening along the Southern San Andreas Fault is as high as 1 in 100, and as low as 1 in 3,000. On the plus side, the likelihood of it happening decreases with each passing day. These estimates are based on models developed to assess the probabilities of earthquakes and aftershocks in California.

“Swarm-like activity in this region has occurred in the past, so this week’s activity, in and of itself, is not necessarily cause for alarm,” cautions the USGS.

That being said, this is only the third swarm that has been recorded in this area since sensors were installed in 1932, and it’s much worse than the ones recorded in 2001 and 2009. This particular stretch of the San Andreas Fault hasn’t ruptured since 1680, and given that big quakes in this area happen about once every 150 to 200 years, this fault line is considerably overdue.

A big fear is that the rupturing of the southern portion of the San Andreas fault could cause a domino effect along the entire stretch, cracking the fault from Imperial County through to Los Angeles County. Another possibility is that the Salton Sea swarm could cause the nearby San Jacinto fault system to rupture, which would in turn trigger the collapse of the San Andreas Fault.

Should the Big One hit, it won’t be pretty. Models predict a quake across the southern half of California with a magnitude around 7.8. Such a quake would cause an estimated 1,800 deaths, 50,000 injuries, and over $200 billion in damage.

But as the USGS researchers point out, this is far from an inevitability. The swarm under the Salton Sea may subside, or fail to influence the gigantic fault nearby. Moreover, the estimates provided by the scientists are exactly that—estimates. The science of earthquake prediction is still very much in its infancy, and these models are very likely crunching away with insufficient data. No need to panic just yet.

Update 10/01/2016 1:35pm – The USGS has updated its estimates, and thankfully, an earthquake seems slightly less like. The agency’s updated statement reads:

Preliminary calculations indicate that, as of 12:00 pm (PDT) on Sept. 30, 2016, there is 0.006% to 0.2% chance (less than 1 in 10,000 to 1 in 500) of a magnitude 7 or greater earthquake being triggered on the Southern San Andreas Fault within the next seven days through October 7, with the likelihood decreasing over time.

[USGS, LA Times]

George is a contributing editor at Gizmodo and io9.