Tag: Earthquakes

The Mystery Of Blue Diamonds And Where They Come From Finally Solved

They are the world’s most expensive diamonds, with some stones valued at £100 million.

But until now nobody has known how rare blue diamonds are made or where they come from.

Now scientists have discovered that they are formed 400 miles down in the Earth, around four times as deep as clear diamonds, where the element boron combines with carbon in such extreme pressure and heat that it crystallizes into the world’s most precious stone.

And because boron is mostly found on the Earth’s surface, scientists believe that it must have travelled down into the mantle when tectonic plates slipped beneath each other.

Eventually volcanic action brought the diamonds up closer to the surface.




The study, published in the journal Nature, suggests blue diamonds are even rarer than first thought.

We now know that the finest gem-quality diamonds come from the farthest down in our planet.”  said Steven Shirey, of the Carnegie Institution of Science.

Blue diamonds have always held a special intrigue. The world’s most famous jewel, the Hope Diamond, which was once owned by Louis XIV, Marie-Antoninette, and George IV was said to be cursed with many of its owners and their families coming to a sticky – and often headless – end.

The postman who delivered the Hope Diamond to its current location in the National Museum of Natural History in Washington DC had his leg crushed in a lorry accident shortly after and then his house burned down.

But the value and rarity of blue diamonds makes them difficult to study and researchers at the Carnegie Institution have spent two years tracking down and studying 46 blue diamonds from collections around the world.

And they were looking for the rarest of blue diamonds, those which include tiny mineral traces called inclusions which hint at their origins.

These so-called type IIb diamonds are tremendously valuable, making them hard to get access to for scientific research purposes,” said lead author Evan Smith of the Gemological Institute of America, adding,

“And it is very rare to find one that contains inclusions, which are tiny mineral crystals trapped inside the diamond.”

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A Powerful Earthquake In Alaska Didn’t Trigger A Big Tsunami

Last Tuesday night, a magnitude 7.9 earthquake struck southeast of Kodiak Island in the Gulf of Alaska, prompting a tsunami warning that forced people to flee to higher grounds in the middle of the night.

Fortunately, the tsunami waves were less than a foot high, and the advisories were canceled a little after 4AM local time. So why was Alaska so lucky?

Powerful quakes that happen out at sea are known to cause destructive tsunamis. In 2011, a magnitude 9 earthquake in northeastern Japan triggered waves as high as 126 feet, killing nearly 20,000 people.




In 2004, a similarly strong quake off the coast of Indonesia caused a tsunami that killed more than 200,000 people.

Alaska also has a history of strong earthquakes: in 1964, the state experienced the most powerful quake ever recorded in the US, a 9.2 magnitude tremor followed by a tsunami that killed over 100 people.

Earthquakes occur because the Earth’s crust is divided into plates. These plates can move smoothly against each other or become stuck.

When they become stuck, they build up strain over time, until one day, the plates unstick, releasing energy that causes an earthquake.

Just south of Alaska, the Pacific plate is sliding underneath the North American plate, an area called the subduction zone. That’s why the state is highly seismic, Blakeman tells said.

Last Tuesday night’s earthquake generated because of all the strain building up on the subduction zone, but it did not occur exactly on a fault where the Pacific Ocean seafloor is sliding under the North American plate, Blakeman says.

Instead, the quake occurred a little farther out, in a place where the fault is moving horizontally.

This type of quake, called a strike-slip earthquake, is less likely to trigger large tsunamis, and this is probably why Alaska only saw waves of less than a foot, according to Blakeman.

When earthquakes happen on the subduction zone itself, where one plate is pushing down while the other is going up, then high waves form.

To get a tsunami, you have to have substantial vertical movement on the seabed,” Blakeman says. Those types of earthquakes were responsible for the massive tsunamis in Japan and Indonesia.

Aftershocks in Alaska could continue for weeks or months, Blakeman says. If the quakes generate from the same zone as last night, then large tsunamis should not be expected.

But because the state sits by the Pacific-North America plate boundary, it’s normal that new earthquakes will happen in the future. When and where, exactly?

That’s impossible to say. Earthquakes are so complicated that scientists aren’t able to predict them — at least not yet. “Since we can’t predict them, all we can do is be prepared,” Blakeman says.

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Scientists Are Slowly Unlocking The Secrets Of The Earth’s Mysterious Hum

“In the deep glens where they lived all things were older than man and they hummed of mystery.”

— Cormac McCarthy, “The Road”

The world hums. It shivers endlessly.

It’s a low, ceaseless droning of unclear origin that rolls imperceptibly beneath our feet, impossible to hear with human ears.

A researcher once described it to HuffPost as the sound of static on an old TV, slowed down 10,000 times.

It’s comforting to think of Earth as solid and immovable, but that’s false. The world is vibrating, stretching and compressing. We’re shaking right along with it.

The earth is ringing like a bell all the time,” said Spahr Webb, a seismologist at Columbia University.

The hum is everywhere. Its ultralow frequencies have been recorded in Antarctica and Algeria, and — as announced this week by the American Geophysical Union — on the floor of the Indian Ocean.

We still don’t know what causes it.




Some have theorized that it’s the echo of colliding ocean waves, or the movements of the atmosphere, or vibrations born of sea and sky alike.

But if we could hear this music more clearly, scientists around the world say, it could reveal deep secrets about the earth beneath us, or even teach us to map out alien planets.

And the hum is getting clearer all the time.

Earth vibrates at different frequencies and amplitudes, for different reasons, and not all those vibrations are the ‘hum’. Earthquakes are like huge gong bangs.

When an enormous quake hit Japan in 2011, Webb said, the globe kept ringing for a month afterward.

People sitting on the other side of the world bounced up and down about a centimeter, though so slowly they didn’t feel a thing.

In 1998, a team of researchers analyzed data from a gravimeter in east Antarctica and realized that some of these vibrations never actually stop.

The phenomenon became popularly known as the “hum of the Earth.

Webb was one of many researchers who searched for the hum’s cause in the 21st century.

Some thought interactions between the atmosphere and solid ground caused the shaking, though he discounts the idea.

Sometimes waves sloshing in opposite directions intersect, sending vibrations deep down into Earth’s crust.

Sometimes a wave on a shallow coast somewhere ripples over the rough sea floor and adds its own frequencies to the hum.

Whatever the origin, the result is a harmony of ultralow frequencies that resonate almost identically all over the globe.

And that’s potentially invaluable to those who want to know what goes on beneath its surface, where the core spins and tectonic plates shift.

Scientists already measure how fast earthquake waves travel through different regions of the underground to make detailed subterranean maps.

The scientists collected data from seismometer stations that had been placed in the Indian Ocean near Madagascar several years ago.

These stations were meant to study volcanic hot spots nothing to do with the hum but the team worked out a method to clean the data of ocean currents, waves, glitches and other noise.

It peaked between 2.9 and 4.5 millihertz, they said — a tighter range than the first hum researchers in the 1990s had recorded.

It was also similar to measurements taken from a land-based station in Algeria.

So more evidence that the hum goes all the way around the world; and more hope that we may one day reveal all that goes on beneath it.

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Earth Will Be Rocked By A Year Of Devastating Earthquakes

earthquake roation

DEVASTATING earthquakes could be on the rise next year as the rotation of Earth slows down, scientists have warned.

The speed of Earth’s rotation fluctuates extremely mildly – extending or decreasing the length of a day by a millisecond – but this tiny deceleration could have devastating consequences.

Scientists have warned if the rotation slows it could lead to more major earthquakes.

Research from Roger Bilham of the University of Colorado in Boulder and Rebecca Bendick of the University of Montana in Missoula looked at earthquakes with a magnitude higher than seven since 1900.




The duo found five years since the turn of the 20th century where there were significantly more 7.0 earthquakes – all of which were years that earth’s rotation speed had slowed down slightly.

Prof Bilham told the observer: “In these periods, there were between 25 to 30 intense earthquakes a year.“The rest of the time the average figure was around 15 major earthquakes a year.”

And in 2018, the Earth’s rotation speed is set to slow down leading to a jump on the six magnitude seven or higher quakes we have had this year.

Prof Bilham said: “The correlation between Earth’s rotation and earthquake activity is strong and suggests there is going to be an increase in numbers of intense earthquakes next year.”

earthquake

The inference is clear. Next year we should see a significant increase in numbers of severe earthquakes.”

We have had it easy this year. So far we have only had about six severe earthquakes. We could easily have 20 a year starting in 2018.

Exactly why a decrease in rotation speed can lead to more major earthquakes is unclear, but experts believe it could be down to changes in the Earth’s core which ultimately has an effect on the surface.

The team also could not say exactly where the earthquakes will occur, but Bilham suggests that a slower rotation speed will lead to more tremors on and around the equator – such as South America, New Zealand and other places that sit on top of the Ring of Fire.

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Plastic Junk Brought Invasive Species to U.S. After Japan’s 2011 Tsunami

In 2011, a massive earthquake shook Japan and reshaped the seafloor. The quake shoved an area the size of Connecticut up by 30 feet.

The tsunami that followed killed roughly 18,000 people. As water swamped the Fukushima Daiichi nuclear power plant, three reactors melted down. Japan’s wounds are still healing.

The tsunami swept 5 million tons of debris into the ocean. Much of the junk did not degrade. Fiberglass boats, far-flung buoys and plastic shards swirled through the Pacific.

Some of the objects came to rest half a world away, like the 60-foot-long polystyrene and concrete dock that landed in Oregon in the summer of 2012.

The dock completed its 4,000-mile journey by beaching itself close to Oregon State University’s Marine Science Center.




A university biologist who specialized in marine invasive species was one of the first people to approach it. Researchers later discovered that the dock harbored close to 100 Japanese species.

That was the neon light,” said marine biologist James Carlton, a Williams College professor based in Mystic, Conn. “That was the harbinger of things to come.”

Carlton and a team of fellow scientists realized the Pacific Northwest faced a flood — not of water but borne by it, of unsinkable junk caked with marine life.

No one could stop the flood, but the researchers could at least document it. The scientists created a network of volunteers in Hawaii and Alaska, down the Pacific Northwest to the middle of California.

State and local officials, park rangers and legions of citizen scientists reported or bagged up what became known, in the biologists’ lingo, as JTMDs: Japanese tsunami marine debris.

If a boat landed on the beach in San Francisco,” Carlton said, “I’d get a call in my lab within a couple of hours.

The JTMDs ferried a lot of animals, as the scientists described in a paper published Thursday in the journal Science.

During six years of study, from June 2012 to February, Carlton and his colleagues counted more than 280 species of Japanese hitchhikers on 600 pieces of debris.

Most were spineless marine critters: sea stars, sea slugs, oysters, barnacles, mussels, amphipods, bryozoa and isopods. Only a few alien arrivals, two species of Japanese fish, had backbones.

This was unlike anything Carlton had witnessed in his 50 years of studying marine invasions, he said. “As time went on, the eyebrows keep going higher and higher. The jaw keeps dropping lower and lower.”

Although the scale of the event was unprecedented, the concept — that rafts carry animals across oceans — was not.

Transoceanic crossings have happened for millions of years.

A recent genetic study of trapdoor spiders found that they must have crossed on a raft from Africa to Australia a few million years ago.

The spider relatives on each continent were too closely related to have last shared an ancestor when Africa and Australia were still geologically connected, some 100 million years back.

Humans have witnessed these arrivals, too. In one well-documented case, 15 iguanas floated atop a cluster of uprooted trees to the Caribbean island of Anguilla in 1995.

The lizards have since established a breeding population on the island.

Of the Japanese species that arrived on the tsunami debris, about a third were already present on the American Pacific coast.

But the foreign animals colonized the wreckage long before the debris came close to shore, Carlton said. The authors of the recent study tracked how currents propelled the debris.

The JTMDs spent the bulk of their journey at sea. “It comes to shore within a few days, acquired by the coastal current — and then, bam! Onto the beach.

The debris at sea becomes like “traveling villages,” Fraser said. “Many rafting organisms brood their young — so their kids grow up on the same raft.” A raft doesn’t have to be artificial.

Fraser and her colleagues tracked marine life that moved hundreds of miles while attached to floating kelp.

Tsunami debris continues to wash up along the Pacific Northwest, most frequently following spring currents. Carlton said he expects the objects and their living cargo to arrive for the next 10 springs to come.

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Why It Is So Hard To Predict Where And When Earthquakes Will Strike?

Can earthquakes ever be predicted? This question is timely after the magnitude 7.8 earthquake that struck Nepal recently. If authorities had more warning that the earthquake was coming, they may have been able to save more lives.

While Nepal is a documented area of previous seismic activity, at the moment there is no technique that provides predictions of sufficient clarity to allow for evacuations at short notice.

So if we cannot predict these events now, are there avenues of research to provide useful predictions in the future?

The key word here is “useful”. It is possible to make long-term forecasts about future earthquake activity, partly by using the past record of earthquakes as a guide.

There is no reason to believe that a region of the Earth is going to behave differently in the next few thousands of years from its pattern over the same range back in time.




In the short term, seismologists can draw on data from recording stations, with records going back roughly 40 years on a global scale.

Within hours of a major earthquake there are estimates of its epicentre, magnitude (the amount of energy released), the depth at which it originated, the orientation of the geological fault that caused it and the direction in which it moved.

The event in Nepal was a thrust fault, meaning that the upper part of the Earth was shortened by a few metres, with the rock lying above the fault plane moving southwards over the rock lying beneath it.

Gathering the data

Information about past earthquakes comes from a number of sources, not least historical records. But such records are incomplete, even in earthquake-prone countries with long traditions of documenting natural disasters, such as China and Iran.

Other lines of evidence are available, including measuring and dating the offsets of man-made or natural features that can be accurately dated, such as the walls of a castle or a city. Faults cutting the Great Wall of China have been documented in this way.

Seismologists also dig trenches across faults known or suspected to be active, and can recover rocks and sediments affected by earthquakes.

These events can dated, for example by radiocarbon analysis of plant remains disturbed by the faulting.

By combining the earthquake ages with the size of the damaged areas, it is possible to understand earthquake patterns over hundreds or even thousands of years.

Scientists use this information as a guideline for future behaviour, but it is clear that the faults do not slip after the same period of time between earthquakes.

Nor does a fault necessarily rupture in the same place in successive earthquakes.

An earthquake releasing stress along one fault segment may place more stress on an adjacent region, thereby increasing the earthquake likelihood in that area.

This may occur soon after the original event, which explains the phenomenon of aftershocks. Nepal has already seen aftershocks of a magnitude greater than six, and is likely to see more.

Global hotspots

Instrumental and historical records combine to make a global picture of earthquake activity. There are, unfortunately, many danger areas.

Eurasia bears the brunt, because of the collision of the Indian and Arabian plates with the rest of Eurasia. Therefore China, Iran, Pakistan and India all share Nepal’s susceptibility to large earthquakes.

Other danger areas lie along the margins of the Pacific and Indian oceans, where one plate slides under another in a process called subduction. Earthquakes at such plate boundaries can cause devastating tsunamis, like in Japan in 2011.

Newer lines of research include precise measurements of the movement of a fault during earthquakes and the motion of the Earth’s surface between earthquakes.

Across the Himalayas there is around 20mm of convergence (shortening) every year, roughly half of the overall convergence between the Indian and Eurasian plates.

The remainder is accommodated further north, in ranges such as the Tian Shan and the Tibetan Plateau.

In other words, every year a person in Siberia becomes roughly 40 mm closer to a person in central India, as the Earth’s crust deforms across the broad region between them.

This strain builds up over time and is released in an earthquake like the snapping of an elastic band.

Faster strain, longer faults and greater strength in the upper part of the Earth in a particular region can all lead to larger earthquakes.

The Himalayas feature a deadly combination of these factors, leading to very large events of the kind experienced on April 25.

It is not sensible to be naively optimistic about improvements in earthquake prediction, but all research on the past and present behaviour of active faults is to be welcomed.

It is timely that the UK’s Natural Environment Research Council has just announced funding for research into earthquakes and resilience to earthquakes.

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