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of the fundamental forces that have shaped our planet.

Restless Planet

Restless Planet (2005) - 275 minutes
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Experience the devastating power of explosive volcanoes, ground-buckling earthquakes, deadly tornadoes, hurricanes and tsunamis as National Geographic heads into the field with scientists who risk their lives to study these fearsome natural phenomena. Featuring over five hours of programming, Restless Planet captures extraordinary scenes of destruction from the air, the ground and from inside a tornado and the moving, human side of the story from tales of heroism and tragedy to dedicated teams of experts racing to understand and ultimately better predict the deadly forces of nature.

Restless Planet includes:

  • Disk 1: Volcano: Nature's Inferno
  • Disk 2: Tsunami: Killer Wave
  • Disk 3: Tornado Intercept
  • Disk 4: Nature's Fury
  • Disk 5: Storm of the Century

1-7-22 Some volcanic hot spots may have a surprisingly shallow heat source
Geologic processes nearer the surface, rather than deep-mantle plumes, may fuel activity there. Some of the world’s volcanic hot spots may be fueled by molten material that originates surprisingly close to Earth’s surface. While some of the hottest spots are fueled by plumes of buoyant material welling up from deep within Earth, as expected, molten flows driving activity at the coolest hot spots may result from relatively shallow geophysical processes, a new study suggests. A lot of our planet’s volcanic activity occurs at or near the edges of the tectonic plates that make up Earth’s crust (SN: 1/13/21). At mid-ocean ridges, which often form the boundaries between some tectonic plates, hot material wells up from the mantle — the hot, thick layer that lies between the Earth’s core and its crust — to create fresh crust. But more mysterious volcanic activity also occurs in many locales in the middle of a tectonic plate, far from mid-ocean ridges, says Xiyuan Bao, a geophysicist at UCLA. The islands of Hawaii, Ascension Island in the South Atlantic and the Pitcairn Islands in the South Pacific are just a few examples of volcanoes created by such activity (SN: 1/29/19). Scientists suspect that many of these sites of isolated volcanism are fed by plumes of hot material rising from deep within the mantle, somewhat akin to small packets of water rising to the surface in a pot of near-boiling water (SN: 9/16/13). But a new analysis by Bao and colleagues, described in the Jan. 7 Science, suggests that some of these isolated hot spots are fueled by material that isn’t as hot as expected, casting doubt that volcanic activity there is driven by deep-mantle plumes. The results could help scientists figure out the mysterious processes unfolding at various sites of volcanism in the interior of plates. “This study helps sort out which volcanic plumes are deep-seated and which are not,” says Keith Putirka, an igneous petrologist at California State University, Fresno who wasn’t involved in the work.

1-6-22 Plumes of rock that feed volcanic hotspots are surprisingly cold
Geologists may need to come up with a new explanation for the sources of volcanic activity in places like Iceland and Hawaii. The plumes of rock feeding Earth’s volcanic hotspots are much cooler than previously thought, suggesting that geologists need to come up with a new explanation for the sources of volcanic activity in places like Iceland and Hawaii. Volcanic hotspots are unconnected to volcanic regions at the boundaries of tectonic plates. They are thought to be fed by hot plumes of rock from deep in Earth’s mantle, which have expanded and risen because of high temperatures. But Carolina Lithgow-Bertelloni at the University of California, Los Angeles, and her colleagues have found that a number of these hotspots are being fed by relatively cold material, which suggests that other dynamics may be at work. “We’re not saying these aren’t hotspots; we’re saying yes they are, but there are different mechanisms that help them rise,” says Lithgow-Bertelloni. ”You may still have slightly warm material that comes up, but it’s not coming up all from depth and all in the same way; it’s being aided by other processes in the mantle.” Calculating the temperature beneath volcanic hotspots is difficult. The upper mantle can be anywhere from 250 to 600 kilometres deep, ruling out direct access. Lithgow-Bertelloni and her team measured the speed of seismic waves travelling underneath volcanic hotspots and inferred temperatures based on a model of the rock make-up. The researchers then compared these temperatures with the relatively cold volcanic regions beneath ridges, at tectonic boundaries. According to classical theory, the plumes need to be between 100°C and 300°C hotter than ridges to rise. But more than half of the hotspots the researchers studied were less than 100°C hotter than ridges. Almost a sixth of the hotspots were essentially cold, meaning they were no more than 36°C hotter than ridges. “You wouldn’t expect very low temperature excesses, because that means you’ve got very little driving force for the thing to blob up and rise in the first place,” says Oliver Shorttle at the University of Cambridge.

3-15-21 One side of Earth's interior is losing heat much faster than the other
Our planet is a bit lopsided. One half of Earth is losing heat from the planet’s interior faster than the other, and has been for much of the past 400 million years. The uneven heat loss is probably a relic of past supercontinents, when all the land masses were joined together on one side of the planet. “We see that the Pacific has lost more heat,” says Krister Karlsen at the University of Oslo in Norway. “That is in large part due to the distribution of the continental land masses.” Karlsen and his colleagues reconstructed the rates of heat loss from Earth’s interior over the past 400 million years by combining two existing data sets. The first concerns the amount of heat from Earth’s interior that flows up through the crust. This data set shows that oceans aren’t as good at trapping heat inside Earth as the continents are, says Karlsen. That is partly down to the thickness of the rock: continental crust is often many kilometres thicker than oceanic crust, so it is a better insulator. The second data set relates to the movement of the continents deep in prehistory. Some continental rocks carry telltale traces of Earth’s magnetic field, which varies around the globe. Data from these rocks can be used to show that Earth has, on several occasions, been home to a supercontinent – and it can help establish some of those supercontinents’ approximate position. The most recent supercontinent was Pangaea, which existed from around 335 to 175 million years ago, and was centred roughly where Africa lies today. When Karlsen and his colleagues reconstructed the pattern of heat loss through the past 400 million years, they found that more heat had been lost from the Pacific hemisphere of the planet than from the opposite African hemisphere, where Pangaea once lay. The Pacific side of our planet was – and still is – dominated by ocean.

7-12-19 3 questions seismologists are asking after the California earthquakes
Tectonic activity may be shifting very slowly away from the San Andreas Fault. A week after two large earthquakes rattled southern California, scientists are scrambling to understand the sequence of events that led to the temblors and what it might tell us about future quakes. A magnitude 6.4 quake struck July 4 near Ridgecrest — about 194 kilometers northeast of Los Angeles — followed by a magnitude 7.1 quake in the same region on July 5. Both quakes occurred not along the famous San Andreas Fault but in a region of crisscrossing faults in the state’s high desert area, known as the Eastern California Shear Zone. The San Andreas Fault system, which stretches nearly 1,300 kilometers, generally takes center stage when it comes to California’s earthquake activity. That’s where, as the Pacific tectonic plate and the North American tectonic plate slowly grind past each other, sections of ground can lock together for a time, slowly building up strain until they suddenly release, producing powerful quakes. For the last few tens of millions of years, the San Andreas has been the primary origin of massive earthquakes in the region. Now overdue for a massive earthquake, based on historical precedent, many people fear it’s only a matter of time before the “Big One” strikes. But as the July 4 and July 5 quakes — and their many aftershocks — show, the San Andreas Fault system isn’t the only source of concern. The state is riddled with faults, says geophysicist Susan Hough of the U.S. Geological Survey in Pasadena, Calif. That’s because almost all of California is part of the general boundary between the plates. The Eastern California Shear Zone alone has been the source of several large quakes in the last few decades, including the magnitude 7.1 Hector Mine quake in 1999, the magnitude 6.7 Northridge quake in 1994 and the magnitude 7.3 Landers quake in 1992 (SN Online: 8/29/18).

6-17-19 Is a long-dormant Russian volcano waking up? It’s complicated
Scientists debate how to interpret quakes near Bolshaya Udina on the remote Kamchatka Peninsula. Seismic rumbles beneath a long-dormant volcano on Russia’s Kamchatka Peninsula could herald an imminent eruption, a team of scientists says. But other researchers say that the observed seismic activity could be related to already erupting volcanoes in the region. Fewer than 10,500 people live within 100 kilometers of the volcano, called Bolshaya Udina, making a catastrophic eruption that would affect large numbers of people extremely unlikely. When the volcano last erupted is unknown, but it hasn’t for at least 10,000 years, so many volcanologists consider it no longer active, or “extinct.” But Kamchatka is home to numerous active volcanoes, including nearby Bezymianny, which most recently erupted March 15. Scientists had detected an apparent increase in seismic activity in the vicinity of Bolshaya Udina beginning in late 2017. So researchers, led by geophysicist Ivan Koulakov of the A.A. Trofimuk Institute of Petroleum Geology and Geophysics in Novosibirsk, Russia, installed four temporary seismic stations near the volcano. From May 5 to July 13, 2018, the stations recorded a swarm of 559 earthquakes. Overall, from October 2017 through February 2019, researchers detected about 2,400 seismic events, the strongest of which was a magnitude 4.3 earthquake in February. Previous to that 16-month period, scientists detected only about 100 weak seismic events in the region from 1999 to 2017. Furthermore, by examining how some of the seismic waves decreased in velocity as they traveled through the subsurface, the team found evidence that there might be a pocket of fluid — perhaps magma — directly beneath Bolshaya Udina. The dramatic uptick in activity, along with the possible detection of magma, could mean that Bolshaya Udina is waking up, the team reports in the July 15 Journal of Volcanology and Geothermal Research.

1-24-19 Skye volcanic eruption 'changed climate'
A catastrophic volcanic eruption on the Isle of Skye is likely to have caused major changes in the world's climate. Researchers from Scotland, Sweden and England have linked the explosion to a prehistoric spike in global warming. It is the first time a large-scale explosive eruption has been confirmed in Scotland The term Palaeocene-Eocene Thermal Maximum (PETM) does not exactly trip off the tongue. It's none too easy to get out of the keyboard either. But it played a huge role in shaping the prehistoric world. It happened about 56 million years ago. We're talking geological timescales here so "about" is close enough. No need to time it down to the second or even millennium. It was a massive climate disturbance that caused global temperatures to shoot up by 8C, four times the increase predicted to create huge problems for present-day humans. Writing in the journal Scientific Reports the researchers say have found evidence of an explosion in the same league as the eruption of Krakatau in 1883. It was one of the biggest volcanic catastrophes in recorded history. The shock waves travelled round the world three and a half times. The huge amounts of particles thrown into the atmosphere caused global temperatures to fall for several years as the ashes blocked sunlight.

12-22-18 Mexico's deadliest volcano
It's a ticking time bomb, experts say — and its eruption could cause damage on the scale of Pompei. On the clear-sky morning of December 21st, 1994, Claus Siebe was standing at the foot of Popocatépetl, watching as elephantine plumes of black smoke and heaps of pyroclastic flow spewed out of Mexico's largest active volcano. Siebe stood silently next to a group of mountaineers, all of whom had their heads cocked upward. He'd never witnessed an eruption on this scale before; he was floored. Recalling that day now, nearly 24 years later, Siebe describes a scene of awe and confusion. "Everybody was watching," Siebe says. "Nobody panicked. We were all just kind of surprised that this was happening." For weeks leading up to the eruption, Siebe, a professor of volcanology at the Universidad Nacional Autónoma de México, had been busy reconstructing the eruptive history of Popocatépetl, a volcano that sits between Mexico City and Puebla and their collective 20 million people. Performing geological and gas measurements, Siebe and his team of researchers concluded that Popocatépetl (which translates to "Smoking Mountain" in the Nahuatl language) was now "reactivating." Four days before Christmas of that year, their hunch was proven correct. Over the next five years, Siebe and his colleagues would deduce that Popocatépetl's latest activity was its first in almost 1,000 years. In a 1996 paper in Geology, Siebe found, through hydrocarbon measurements and biometric dating, that the volcano experienced what's called a Plinian eruption — meaning an eruption that bears structural similarities to Mount Vesuvius' mythically destructive outburst; so named in honor of Pliny the Younger, the hawk-eyed Roman who witnessed the horror — around 215 B.C.E, and again around 823 C.E. In short, it had experienced its share of Big Ones, as he calls them. Siebe's research had estimated the occurrence of a Big One "every millennia or so," a calculation that, even with advances in monitoring technology, is a scientific shot in the dark. Among the wreckage his modeling predicts: the general devastation of everything in an eight-mile radius. In the years since the 1994 eruption, Siebe and his colleagues have witnessed a handful of eruptions placed in categories of "High Risk" to "Medium Risk" — categorizations that are determined by the expanding radius of a destruction zone from Popocatépetl's mouth — the worst being in 2000, 2003, 2013, and 2015. Theoretically speaking, the eruptions Siebe's categorized thus far from the volcano have been kind of like a treatable array of kitchen fires; a Plinian eruption, in line with its historical magnitude, would be sure to engulf the entire house. He and his team are certain that the question isn't if Latin America's deadliest volcano is going to have another Big One. It's when.

10-9-18 Falling rocks can explode so hard that only nuclear weapons beat them
If big rocks fall far enough they can explode with more energy than any non-nuclear bomb – and the ensuing shockwave can snap large trees half a kilometre away. If falling rocks are big enough and hit the ground hard enough they can create a blast so intense that the rocks are pulverised into powder. Such extreme rockfalls are followed by a shockwave that can snap trees hundreds of metres away. “They’re extremely weird phenomena, which have been somehow overlooked,” says Fabio De Blasio of the University of Milano-Bicocca in Italy. The first known example took place in Yosemite National Park, California, on 10 July 1996. Two large masses of rock fell from Glacier Point and plummeted 665 metres. When they hit the ground they released a blast of air that snapped or toppled about 1000 trees, including some half a kilometre away. This was followed by a cloud of abrasive sand, which scoured the fallen trees. The rockfall was described by researchers in 2000 but it remained a curiosity. Now De Blasio and his colleagues have identified 21 other “extremely energetic rockfalls” from the past two decades, mostly from the European Alps and the Dolomites in Italy. They argue that these extreme events are more common than had been thought. The crucial point is that the impact of the rocks on the ground is so violent that they are smashed into powder. This needs a big mass of rocks, on the order of 10,000 cubic metres, to pick up speed by falling several hundred metres. “Typically they will develop in areas where erosion has been quite fast,” says De Blasio. Yosemite is a steep gorge eroded by the Merced river, so it has lots of steep cliffs that are ideal.

3-24-18 Mount Etna is 'sliding towards the sea'
Europe's most active volcano, Mount Etna, is sliding towards the sea. Scientists have established that the whole structure on the Italian island of Sicily is edging in the direction of the Mediterranean at a rate of 14mm per year. The UK-led team says the situation will need careful monitoring because it may lead to increased hazards at Etna in the future. The group has published its findings in the Bulletin of Volcanology. "I would say there is currently no cause for alarm, but it is something we need to keep an eye on, especially to see if there is an acceleration in this motion," lead author Dr John Murray told BBC News. The Open University geologist has spent almost half a century studying Europe's premier volcano. In that time, he has placed a network of high-precision GPS stations around the mountain to monitor its behaviour. This instrumentation is sensitive to millimetric changes in the shape of the volcanic cone; and with 11 years of data it is now obvious, he says, that the mountain is moving in an east-south-east direction, on a general track towards the coastal town of Giarre, which is about 15km away. Essentially, Etna is sliding down a very gentle slope of 1-3 degrees. This is possible because it is sitting on an underlying platform of weak, pliable sediments. Dr Murray's team has conducted lab experiments to illustrate how this works. The group believes it is the first time that basement sliding of an entire active volcano has been directly observed.

1-25-18 These are the worst ready-made sandwiches for the climate
Producing ready-made sandwiches can generate twice as much carbon dioxide as simply making them at home, and one particular filling is egregiously bad. As well as saving money, making your sandwiches at home will help save the planet. Adisa Azapagic of the University of Manchester, UK and her colleagues have studied the carbon footprint of the 11.5 billion sandwiches eaten in the UK each year. They worked out how much greenhouse gas is released by making 40 types of sandwich. Overall, they found that the UK sandwich industry releases the equivalent of 9.5 million tonnes of carbon dioxide. However, homemade is better. “The main reason is that in commercial sandwiches you have longer refrigeration chains, plus packaging, and waste tends to be higher from bought sandwiches,” says Azapagic. The most climate-friendly sandwich studied is a plain, homemade cheese and ham sandwich. On average, depending on quantities in in the sandwich, it generates 550 grams of carbon dioxide equivalent, the same as driving a car for 6 kilometres. The worst is a commercial egg, bacon and sausage “all-day-breakfast” sandwich, with corresponding values of 1440g and 19km. The least harmful commercial sandwich was egg mayonnaise with cress, with carbon footprint figure of 740g, equivalent to driving 10km. The largest contributors are the farming and processing of ingredients, which account for 37 to 67 per cent of the footprints for ready-made sandwiches. Refrigeration in stores accounts for 25 per cent, and packaging 8.5 per cent.

1-25-18 Ring of Fire's volcanic and quake activity is normal, say scientists
Tens of thousands of people have had their lives disrupted in the past week by seismic and volcanic activity along the Ring of Fire. An earthquake off Alaska, an avalanche and volcanic eruption in central Japan and a volcano squirting lava in the Philippines all occurred within days of each other. It led the UN Office for Disaster Risk Reduction to send a tweet on Tuesday warning that the Ring of Fire was "active". Many are asking whether there is cause for concern that something more serious might happen. So is there reason to worry? The Ring of Fire refers to a string of volcanoes, earthquake sites and tectonic plates around the Pacific. It spreads across 40,000km (25,000 miles) from the southern tip of South America all the way to New Zealand. Roughly 90% of all earthquakes occur along the area and the ring is dotted with 75% of all active volcanoes on Earth, that's 452 individual active volcanoes. This week alone, a 7.9-magnitude earthquake struck off the coast of Alaska in the US. The quake briefly triggered a tsunami warning for coastal areas of Alaska and British Columbia in Canada. On the same day, one soldier was killed and at least 11 others injured in central Japan by an avalanche that may have been triggered by a volcanic eruption. The eruption of Mount Moto-Shirane, which is part of Mount Kusastsu-Shirane, also sent rocks raining down a kilometre-wide area near Kusatsu in central Japan, local media reported. Earlier last year, the eruption of Bali's Mount Agung led to the closure of the city's international airport and forced up to 100,000 people to evacuate.

1-23-18 Huge volcano eruption in the Philippi
More than 50,000 villagers were forced to flee their homes after the most active volcano in the Phillipines, Mount Mayon, spewed lava and ash plumes. The most active volcano in the Philippines spewed fountains of lava and massive ash plumes in a new eruption today that forced more than 50,000 villagers to evacuate. Fountains of lava fountains gushed 700m up above Mount Mayon’s crater and ash plumes rose up to 3km, according to the Philippine Institute of Volcanology and Seismology. An explosive eruption at noon local time on Monday was the most powerful since the volcano started acting up more than a week ago. Authorities warned that a violent eruption may occur in hours or days, characterised by more rumblings and pyroclastic flows – superheated gas and volcanic debris that race down the slopes at high speeds. After Monday’s explosion, officials raised Mayon’s alert level to four on a scale of five, and the danger zone was expanded 8km from the crater, requiring thousands more residents to be evacuated, including at least 12,000 who returned to their homes last week as Mayon’s rumblings temporarily eased and then scrambled back to the emergency shelters this week. At least 56,217 people were taking shelter in 46 evacuation camps on Tuesday and army troops and police were helping move more villagers from their homes, officials said.

1-15-18 Mount Etna may not really be a ‘proper’ volcano at all
Italy’s famous volcano Mount Etna may be fed mostly by hot water and carbon dioxide, with only a small dose of molten rock to make it resemble a classic volcano. Mount Etna, one of the world’s most famous volcanoes, may be misunderstood. According to one geologist, the material feeding the cone is mostly water, so Etna is effectively a giant hot spring. But other geologists are unconvinced. Mount Etna in Italy is almost constantly active. It’s been estimated that it spewed about 70 million tonnes of lava in 2011 alone. But what really puzzles Carmelo Ferlito at the University of Catania, Italy – about 30 kilometres from the volcano – is that Etna also belches out more than 7 million tonnes of steam, carbon dioxide and sulphur dioxide every year. The conventional explanation is that this gas bubbles out of magma as it loses pressure on its way up through the volcano’s vent. But Ferlito says Etna would need to erupt ten times more lava than it does to account for all the gas that burps out. Alternatively, maybe most of the molten rock in Etna loses its gas and sinks again, without erupting. But Ferlito’s calculations suggest that sustaining the gas emissions would require a fresh injection of 10,000 kilograms of magma every single second. This would “inflate the volcano like a children’s balloon”, he says. So instead, Ferlito argues the easiest way to explain Etna’s excess gas is to ditch the idea that it is fed only by magma. He has calculated that the volcano’s deep plumbing system could hold lots of water, carbon dioxide and sulphur, collectively making up about 70 per cent of the volume of material feeding the volcano. “Only 30 per cent is molten rock,” he says.

9-3-17 North America’s largest recorded earthquake helped confirm plate tectonics
North America’s largest recorded earthquake helped confirm plate tectonics
‘The Great Quake’ tells the story of the 1964 Alaska temblor. In 1964, the largest recorded earthquake in North American history shook Alaska to its core (damage in Anchorage, shown) and provided proof of tectonic plate movement. In the early evening of March 27, 1964, a magnitude 9.2 earthquake roiled Alaska. For nearly five minutes, the ground shuddered violently in what was, and still is, the second biggest temblor in recorded history. Across the southern part of the state, land cracked and split, lifting some areas nearly 12 meters — about as high as a telephone pole — in an instant. Deep, house-swallowing maws opened up. Near the coast, ground turned jellylike and slid into bays, dooming almost everyone standing on it. Local tsunamis swamped towns and villages. Not many people lived in the newly formed state at the time. If the quake had struck in a more developed place, the damage and death toll would have been far greater. As it was, more than 130 people were killed. In The Great Quake, Henry Fountain, a science journalist at the New York Times, tells a vivid tale of this natural drama through the eyes of the people who experienced the earthquake and the scientist who unearthed its secrets. The result is an engrossing story of ruin and revelation — one that ultimately shows how the 1964 quake provided some of the earliest supporting evidence for the theory of plate tectonics, then a disputed idea.

8-15-17 Seismologists get to the bottom of how deep Earth’s continents go
Seismologists get to the bottom of how deep Earth’s continents go
Analysis of seismic waves finds runny rock layer where landmass ends. Earthquake vibrations are revealing just how deep the continents beneath our feet go. Researchers analyzed seismic waves from earthquakes that have rocked various regions throughout the world, including the Americas, Antarctica and Africa. In almost every place, patterns in these waves indicated a layer of partially melted material between 130 and 190 kilometers underground. That boundary marks the bottom of continental plates, argue Saikiran Tharimena, a seismologist at the University of Southampton in England, and colleagues. Their finding, reported in the Aug. 11 Science, may help resolve a longtime debate over the thickness of Earth’s landmasses. Estimating continental depth “has been an issue that’s plagued scientists for quite a while,” says Tim Stern, a geophysicist at Victoria University of Wellington in New Zealand, who wasn’t involved in the work. Rock fragments belched up by volcanic eruptions suggest that the rigid rock of the continents extends about 175 kilometers underground, where it sits atop slightly runnier material in Earth’s mantle. But analysis of earthquake vibrations along Earth’s surface have suggested that continents could run 200 or 300 kilometers deep, very gradually transitioning from cold, hard rock to hotter, gooier material.

1-4-17 Molten iron river discovered speeding beneath Russia and Canada
Molten iron river discovered speeding beneath Russia and Canada
DEEP below our planet’s surface, a molten jet of iron, nearly as hot as the surface of the sun, is picking up speed. This stream of liquid some 420 kilometres wide has been discovered by telltale magnetic field readings 3000 kilometres below North America and Russia. It has trebled in speed since 2000, and is now circulating westwards at between 40 and 45 kilometres per year, heading from deep under Siberia towards the underside of Europe (see diagram). That is three times as fast as the typical speeds of liquid in the outer core. No one knows yet why the jet has got faster, but the team that made the discovery thinks it is a natural phenomenon, and can help us understand the formation of Earth’s magnetic fields, which keep us safe from solar winds. “It’s a remarkable discovery,” says Phil Livermore at the University of Leeds, UK, who led the team. “We’ve known that the liquid core is moving around, but our observations haven’t been sufficient until now to see this jet.” “We know more about the sun than the Earth’s core,” says team member Chris Finlay from the Technical University of Denmark in Kongens Lyngby. “The discovery of this jet is an exciting step in learning more about our planet’s inner workings.” What made the discovery possible was the combined monitoring power of the European Space Agency’s trio of satellites, called Swarm, which were launched in 2013. From orbit, they can measure magnetic field variations down to 3000 kilometres below Earth’s surface, where the molten core meets the solid mantle.

1-3-17 'Better estimate' of volcanic ash cloud return
'Better estimate' of volcanic ash cloud return
Potentially disruptive volcanic ash clouds across Northern Europe occur more frequently than previously thought, according to new research. Scientists investigated known and newly identified records of ash fall deposits over the past few thousand years and concluded the average return rate to be about 44 years. Previous research had put the recurrence at roughly 56 years. The source of the ash is almost always from Iceland. In 2010, the island’s Eyjafjallajökull volcano erupted, throwing some 250 million tonnes of fine particles into the atmosphere that grounded planes across Europe. The eruption of Grímsvötn the following year also disrupted air traffic - albeit on a much smaller scale. But despite these two recent, closely spaced events, the team behind the latest research says the general frequency of volcanic ash clouds over Northern Europe is still generally quite low.

11-4-16 Huge lake discovered 15 kilometres under a volcano
Huge lake discovered 15 kilometres under a volcano
The discovery of a vast reservoir of water – as big as the largest freshwater lakes – could help reveal how eruptions occur, and how continental crust forms. Our planet is blue inside and out. A massive reservoir of water has been discovered deep beneath a volcano in the Andes, and Earth’s interior may be dotted with similar wet pockets lurking below other major volcanoes. The unexpected water, which is mixed with partially melted magma, could help to explain why and how eruptions happen. This water may also be playing a role in the formation of the continental crust we live on, and could be further evidence that our planet has had water circulating in its interior since its formation.

11-1-16 Mount St. Helens is a cold-hearted volcano
Mount St. Helens is a cold-hearted volcano
Scientists are still searching for the source of volcano’s heat. While a volcano called Mt. Adams is fed by an obvious heat source, Mount St. Helens sits above a wedge of rock formed at the edge (or “cold nose”) of the North American tectonic plate. Below most volcanoes, Earth packs some serious deep heat. Mount St. Helens is a standout exception, suggests a new study. Cold rock lurks under this active Washington volcano. Using data from a seismic survey (that included setting off 23 explosions around the volcano), Steven Hansen, a geophysicist at the University of New Mexico, peeked 40 kilometers under Mount St. Helens. That’s where the Juan de Fuca tectonic plate melts as it sinks into the hot mantle beneath the North American plate, fueling an arc of volcanoes that line up like lights on a runway. All except for Mount St. Helens, which stands apart about 50 kilometers to the west. Still, Hansen and colleagues expected to see a heat source under Mount St. Helens, as seen at other volcanoes. Instead, thermal modeling revealed a wedge of a rock called serpentinite that’s too cool to be a volcano’s source of heat, the researchers report November 1 in Nature Communications. “This hasn't really been seen below any active arc volcanoes before,” Hansen says.

Restless Planet

Sioux Falls Scientists endorse Restless Planet for describing some
of the fundamental forces that have shaped our planet.