lithospheric

Supercomputing helps researchers understand Earth’s interior

Contrary to posters you may have seen hanging on the walls in science buildings and classrooms, Lijun Liu, professor of geology at Illinois, knows that Earth’s interior is not like an onion.

While most textbooks demonstrate the outer surface of the Earth as the crust, the next inner level as the mantle, and then the most inner layer as the core, Liu said the reality isn’t as clear-cut.

“It’s not just in layers, because the Earth’s interior is not stationary,” Liu said.

In fact, underneath our feet there’s tectonic activity that many scientists have been aware of, but Liu and his team have created a computer model to help better explain it – a model so effective that researchers believe it has the potential to predict where earthquakes and volcanoes will occur.

Using this model, Liu, along with doctoral student Jiashun Hu, and Manuele Faccenda from the University of Padua in Italy, recently published a research paper in the journal of Earth and Planetary Science Letters that focuses on the deep mantle and its relationship to plate tectonics.

“It’s well-known that there are plate tectonics driving the Earth’s evolution, but exactly how this process works is not entirely clear,” he said.

Liu and Hu looked specifically at the continent of South America to determine which tectonic factors contribute to the deformation, or the evolution, of the mantle.

To answer this question, the team created a data-centric model using the Blue Waters supercomputer at the National Center for Supercomputing Applications at Illinois. The sophisticated four-dimensional data-oriented geodynamic models are among the first of their kind.

“We are actually the first ones to use data assimilation models in studying mantle deformation, in an approach similar to weather forecasting,” Liu said. “We are trying to produce a system model that simultaneously satisfies all the observations we have. We can then obtain a better understanding about dynamic processes of the Earth evolution.”

While there are many debates in regards to how the Earth’s internal evolution is driven, the model created by the team seemed to find an answer that better fits available observations and underlying physics. The team found that the subducting slab – a portion of the oceanic plate that slides beneath a continental plate – is the dominant driving force behind the deformation of the mantle.

Essentially, the active subduction of the slab determines most other processes that happen as part of a chain reaction. “The result is game-changing. The driving force of mantle flow is actually simpler than people thought,” Liu said. “It is the most direct consequence of plate tectonics. When the slab subducts, it naturally controls everything surrounding it. In a way this is elegant, because it’s simple.”

By understanding this mechanism of Earth evolution, the team can make better predictions regarding the movement of the mantle and the lithosphere, or crust.

The team then evaluated the model’s predictions using other data. Hu, the lead author on the paper, said that by comparing the predictions to tectonic activities such as the formation of mountains and volcanoes, a clear consistency emerged.

“We think our story is correct,” Hu said.

Consequently, the model also provides interesting insight on the evolution of continents as far back as the Jurassic, when dinosaurs roamed the Earth on Pangaea, the only continent at the time. This is still the team’s ongoing research.

Liu said that in a separate paper that uses the same simulation, published by Liu and Hu in Earth and Planetary Science Letters in 2016, the model provided an accurate prediction for why earthquakes happen in particular locations below South America. He explained that earthquakes aren’t evenly spread within the subducting slab, meaning there are potentially areas where an earthquake is more or less likely to take place.

“We found that whenever you see a lack of earthquakes in a region, it corresponds to a hole in the slab,” Liu said. “Because of the missing slab in the hole, there’s no way to generate earthquakes, so we might be able to know where more earthquakes will take place.”

The model also explained why certain volcanoes might exist further inland and have different compositions, despite the common thought that volcanoes should exist solely along the coast, as a result of water coming off the down-going slab. As the model helps explain, a volcano can form inland if the slab subducts at a shallower angle, and a hole in the shallow slab allows for a special type of magma to form by melting of the crust.

“Ultimately this model will provide a promising way of solving the question of how and why continents move the way they do,” Liu said. “The answer should depend on what the mantle is doing. This is a way to much better understand Earth evolution.”

The team is currently expanding the model to analyze the entire globe.

“We are looking forward to more exciting results,” Liu said.

IMAGE….Researchers created a three-dimensional representation of predicted slab geometry and mantle flow. The image outlines areas with a temperature at 300 degrees Celsius cooler than the surrounding mantle, with different colors representing different depths. Oceanic plates and slabs are semi-transparent, and continents are entirely transparent. Green arrows represent velocity vectors inside the mantle Credit Lijun Liu, University of Illinois.

noicecream  asked:

The lithosphere, which is the rigid outermost shell of a planet (crust and upper mantle), is broken up into tectonic plates.The Earth's lithosphere is composed of seven or eight major plates (depending on how they're defined) and many minor plates.

Cool. We can fit seven or eight major plates into our dishwasher.

5

A Guide to the Energy of the Earth

Energy moves in and out of Earth’s physical systems, and during any energy transfer between them, some energy is lost to the surroundings as heat, light, sound, vibration, or movement.

Our planet’s energy comes from internal and external sources. Geothermal energy from radioactive isotopes and rotational energy from the spinning of the Earth are internal sources of energy, while the Sun is the major external source, driving certain systems, like our weather and our climate.

Sunlight warms the surface and atmosphere in varying amounts, and this causes convection, producing winds and influencing ocean currents. Infrared radiation, radiating out from the warmed surface of the Earth, gets trapped by greenhouse gases and further affects the energy flow.

From the TED-Ed Lesson A guide to the energy of the Earth - Joshua M. Sneideman

Animation by Marc Christoforidis

Deep heat melts Greenland’s icy base

We have heard stories in recent years of the retreat of Arctic ice and the increasing amounts of summer melt, seemingly linked to global climate change. The idea that ice will melt as the atmosphere or oceans warm is rather intuitive. But news is reported today highlighting the influence of Earth’s interior heat flow on the glacial melt.

Keep reading

A new map of Mars’ gravity made with three NASA spacecraft showing the Tharsis volcanoes and surrounding flexure. The white areas in the center are higher-gravity regions produced by the massive Tharsis volcanoes, and the surrounding blue areas are lower-gravity regions that may be cracks in the crust (lithosphere).

rodzilla-world  asked:

I have asked this question in other places, but still have a few unexplained issues. About all this talk of terraforming Mars: I was under the impression that Mars lost whatever atmosphere it may have once had because of the planet's smaller size, meaning not enough gravity to "hold onto" it. The other theory I read about involved Mars' magnetic field. So how would it be possible to recreate livable conditions, now?

Hi there!

Mars actually does have an atmosphere. It’s very very very very tenuous, but there’s something there (Think about it this way, the surface of the Earth has the pressure of ~101 kilopascals (that’s 101,000 pascals), whereas Mars has ~600 pascals. Big difference, but I would still call it an atmosphere. The planet is ¼ the size of Earth, but it should still have enough gravity to “hold on” to some of the heavier gases (carbon dioxide, methane, etc). If you’re talking about H, or He, then yeah, that might not be enough gravity to hold on it. But that goes the same for Earth. H and He are light in general.

Okay, so I’ve already answered the question way back about the ways which we can terraform Mars. Here’s the answer below, and this is the link to it

Here’s the issue with terraforming Mars:

  • Temperature: Martian nights average to approximately 186K (-87 ˚C), and an average Martian day is approximately 268K (-5˚C), both of which is below the freezing point of water, and thus all water on Mars exists in solid form. It would be difficult to find anything to drink—need energy to melt the ice. Also, there would be no lakes/rivers/oceans to drive the water cycle. No water for plants and animals. Worst of all, no coffee!!
  • Atmosphere: Mars has a very tenuous atmosphere. It would be difficult to breathe because of the difference in pressure (again, we are used to approx. 1atm. Mars has about 6 x 10-3 atm).  Also, it’s mainly composed of CO2, although too thin to provide a substantial greenhouse effect, it’s still at a high enough percentage for carbon dioxide poisoning for humans. 
  • Weather: Tidal heating can lead to a dynamic cycle of CO2 sublimation/condensation. This can lead to high wind speeds, which would not be good for structural engineering, or aerospace engineering. Also, prevalent dust storms can lead to issues with…dust getting everywhere…visibility…etc. Dust storms can also change the albedo, though that might not affect human habitability as it would have by directly affecting the surface inhabitants. 
  • Nitrogen: There’s missing nitrogen in the Martian atmosphere. The nitrogen gas is an important component of the Earth atmosphere. While this might not be a huge deal, the nitrogen cycle itself is crucial to Earth life forms. Plants and bacteria are in an extremely intimate relationship via nitrogen cycling (ammonia to nitrates back to ammonia, etc). This would make it difficult for plant life to exist on Mars. If there’s nitrogen fixing bacteria around, theoretically, it can recycle the nitrates that we *think* is locked up in Martian regolith, and provide nutrients to plant/animals. Nitrogen is a crucial element for life (DNA, protein, etc). 
  • Radiation: Because of its tenuous atmosphere, and negligible (or non-existent?) magnetic field, Mars does not have a steady protection from the Sun’s radiation. So the surface is constantly bombarded with UV, cosmic rays, crazy electromagnetic waves etc. Humans wouldn’t be able to withstand this high amount of a radiation—we don’t have the biological capacity to reverse such damage (some bacteria might). 
  • Geology: Mars has a super thick lithosphere, no tectonic plates, and has many inactive (big) volcanoes. This inactive geology would make habitability difficult because there would be no movements of plates, thus no water, thus no ocean (it’s too cold anyway), thus no water cycle. Also because it’s so small, Mars may have already lost most/all of its heat. Regardless of how much energy we can pump into the system to make it warm/habitable, it’s going to become a frozen world one day, completely unable to warm up enough using solely internal heat. But this would take a very very long time, so it might not be a huge issue with temporary terraformation. 

Here is how to solve it:

  • Temperature & Atmosphere: If we pump up the heat a *little* bit (no, actually, a lot—but a little bit on a thermodynamic scale), we might be able to unlock the subsurface water that is buried underneath Martian regolith as ice. Something like this can be solved by increasing the amount of greenhouse gas in the atmosphere, to drive up the effective temperature. Pumping CO2 would require possibly jump starting a volcano (how on Earth can that even be done??—not a pun). A more plausible idea is to build power plants all over the planet (as have suggested by Chris McKay from NASA). Or simply by seeding the planet with respiring life that uses inorganic molecules to utilize energy and produce CO2. Early microbial life forms do this (before the evolution of cyanobacteria/photosynthesis). Those microbes were methanogens, sulfur-loving, and can probably also metabolize nitrates. 
  • Weather: Dust storms can be mitigated by living in closed quarters. 
  • Radiation: The problem with UV radiation (and lack of magnetic field) can probably be solved by producing artificial magnetic field. This kind of engineering can only applied to small area, not globally. Again, it’s almost impossible to jump start the solid core again, therefore such an issue can only be tackled on a small scale. 
  • Geology: Mars would have a similar problem as Venus. While there might be enough water on the surface, there’s no convection in the mantle to drive tectonic plates. So while its geology might be change momentarily (lasting maybe about a billion years), it would be difficult to keep it stable as the planet loses more and more heat.  
  • Ethics!!: If there is no Martian life, yes, we should terraform it (although we could never be sure—ack, science!). If there is Martian life, we must do everything we can to preserve it—not necessarily protect it, but at the very least observe/study it without directly affecting it like we have done so for many other endangered species on Earth. 

This is copied verbatim from one of my homeworks from my astronomy class last semester, The Science and Fiction of Planetary Systems

The actual problem with terrafoming Mars is MONEY. Who will pay for what, and which nation should get what piece of land— It’s all politics that I’m not willing to discuss. 

But we will get there. I absolutely believe it. We will get there. 

It’s a Geological Life: Spain Edition

Day 4: to Etang de Lers and FREAKING MANTLE ROCKS!!

July 21, 2016

Oh, the mantle was beautiful!

The Mantle in Etang de Lers

In the central Pyrenees, France, is the Lherz Massif, which displays one of the best exposures of the subcontinental lithospheric mantle. These Pyrenean orogenic peridotites are comprised of 40 distinct ultramafic bodies of  intermingling harzburgites and spinel lherzolites. The massifs are associated with crustal granulites and are embedded within carbonate rocks of Jurassic age. The carbonate rocks are affected by the low-pressure/high-temperature metamorphism. The exhumed mantle rocks are located within the North Pyrenean Matamorphic Zone. 

During the Lower Cretaceous, the Iberian plate (Spain) was experiencing regional rifting, which was localized along the North Pyrenean Fault Zone. The fault zone created extensional basins by transcurrent movement (strike-slip) activity. 

(Not my photos and I do not know where my professor got it. If anyone know, please tell me. I would like to give credit.)

In these basins, there was crustal thinning and resulted in the Low P-High T metamorphism. Ganolithic and ultramafic mantle rocks were emplaced in the upper crust. After the strike-slip activity, convergence between the Afro-Iberian and European plates formed an inversion of Late Jurassic and Earth Cretaceous extensional basins. The collision formed a doubly verging collisional mountain belt and pushed the mantle rocks to the surface. 


(From: “Active Tectonics of the Pyrenees: A review”)

The lovely J.D. is hammering away at the carbonate host rock.

The mighty Clark is delicately holding a beautiful sample of lherzolite

the story goes like this:

he spent the day with his friends so she had to wait for him to come back. had to take her mind off of him. so she took care of her niece for ten hours straight, she was never fond of selfies but she tried every snapchat filter that day. because she had to not think about him. she had to forget for a while, that he was not there. she assumed that vodka would be too strong and that she might forget everything. brown eyed girl just wanted to do something else because waiting would mean she misses him, and she was tired of missing him. to be honest it’s been a week. she felt the distance. like fault lines across the lithosphere, unfinished bridges or the ones waiting to be burned down.

brown eyed girl said hi over messenger. “hi?? are you ignoring me???” brown eyed girl needed to vent. brown eyed girl was fed up. brown eyed girl was tired or waiting. but she wouldn’t let him know that. because if he knew she was upset because of him, they would argue. and that was the last thing that they needed.

still, they fought over messenger. something about her apologizing for being a bitch and him trying to help. she said he didn’t know how to listen, he told her she didn’t do anything wrong. she apologized but he wouldn’t accept. because for him, she was not in the wrong. she had to beg him to accept her apology, he did, eventually.


the story goes like this:

brown eyed girl says hi over messenger and they forget about what happened moments before because they know that having each other is more important that their petty fights. brown eyed girl cracks jokes over messenger and he laughs. she hears it through the songs blasting on her earphones. she smiles. brown eyed girl is happy again.


the story goes like this:

brown eyed girl will apologize even if she knows she’s not in the wrong. brown eyed girl will forgive him for this, will forgive him in the future, will forgive him either way because she loves him. brown eyed girl loves him and tonight he will sleep alright.

—  dad told me to forgive, mom taught me how to love