At present you can unknowingly stand on top of a mountain.
Although it sounds like a fantastic feature of Jules Verne's journey to the center of the earth underground mountains are real, albeit different from any novelist's planned landscape. This strange area is part of the layered structure of our planet, ripples along a geological boundary about 410 miles down. It contains huge peaks, with some being able to towers even higher than the mighty Mount Everest.
Now, scientists have their best appearance yet on these underground mountains using the seismic waves from several major earthquakes. Published recently in Science suggests their analysis that peaks are not only high but surprisingly robust ̵
"Because we have been able to observe so much already, people believe that we have made the most of the first-order discoveries and that everything else is adding details to the basic discoveries," says Christine Houser. a global seismologist at the Institute of Science at the Tokyo Institute of Technology.
But as this study shows, "we" are still able to make fundamental discoveries of the interior of our own planet. "
Earth's mantle constitutes about 84 percent of our planet's mass and acts as A slow-moving convection drives the stable march of plate tectonics, which sends plates in depth, meanwhile increasing magma freely spreads on the surface and provides a fresh supply of minerals.
"Almost everything about how life has evolved depends on this fluxing of elements from the surface, "says Elizabeth Day, a deep-ground seismologist at Imperial College London who was not involved in this work." We need plates to sink and volcanoes erupt and all these kinds of things to support the bikes we have on the ground. "
But how much our mantle flows and mixes is still unknown. Think of it as a yogurt cup with fruit on the bottom; did the sweet jelly stir up through the tangy dairy product?
This is an important question, because soil in relation to other rocky bodies in our solar system seems to lack some elements. For example, chondrites are rocky meteorites that scientists believe may be remnants of the ancient planetary formation. If so, they must be similar in composition to the earth's stones. But, unlike condoms, the earth's cover has a relatively small amount of silicon compared to magnesium.
This is where deep mixing can come into play. Some of the "missing" elements like iron could turn into the planet's core, but it's not clear where others can hide. Part of the problem is that it's hard to figure out what lies miles below our feet.
Previous work using earthquake waves showed that these seismic signals dance around the border 410 miles deep in ways that suggest that the rocks below are closer than the above. Other hints come from the chemistry of volcanic monasteries, remnants of a molten mantle, and rare jackets of mantle brought to the surface.
The image that has emerged is much different from the standard yellow and red layers seen in most earth charts; much of the upper mantle is likely to light live green olivine, while more dark roses mixed with blue minerals flash over the border 410 miles down, and terrestrial bridgmanite sits below.
Most researchers agree that the changes in density are from physical rearrangements of elements in different crystal structures, similar to graphite turning to diamond at high pressure and temperatures, explains study leader Wenbo Wu, who completed the work as a PhD. students at Princeton University. But there could also be chemical differences.
"Perhaps our understanding of what the earth is made of is hampered by the few samples we have of what the mantle is," said Jackie Caplan-Auerbach, a seismologist at Washington University.
To look into the interior of the earth for this latest work, Wu and his colleagues turned to reverberation from really big earthquakes. Wu, now a postdoc at the California Institute of Technology, resembles the process of reflecting light from a mirror. If the mirror is completely flat, the light reflects clean. But add some bumps and curves to the mirrored surface and the recurring rays will spread.
"This is a similar idea to our study," Wu says. "The difference is that we look at seismic waves." The team especially exploited the earthquake force, which smoked the earth as a bell, sending waves all the way through our planet and back again to look at the spread from its interior structures. To achieve this achievement, the researchers looked at earthquakes that were at least 6 and began quite deeply. They then drafted the signals from several earthquakes in the hope that patterns would emerge that could reveal details of the underground landscape.
A Vault of Early Earth
These great earthquakes dug up some surprising information: Some regions of the border where Deep Mountain areas are remarkably robust, with towering ravines rising from the flanks of the underground peaks. Although it is difficult to give the exact heights of the hard areas, Wu says, their presence points to some kind of chemical differences in the mantle.
The authors suggest that the robustness could be a cemetery for stone slabs originating from the surface at subduction zones where a tectonic plate is pushed under another. When a plate sinks down, the pieces eventually break free and continue their sliding into the depth. But it seems that some can be hung up 410 miles down, and the slope of these plates can be what creates the rough, crooked part of the border region.
This will again indicate regions where the mantle does not mix. Other border regions seem smooth and can therefore be mixed much more freely and suggested that the sheath generally has areas of deep mixing and zones that are slower to mix.
In addition, the work suggests that the Earth's "missing" elements may deceive under these rugged areas. As Houser explains, some zones in the lower cloak can withstand mixing since the Earth's early years and keep some chemical components trapped in the depths. The trick is that it is difficult to say exactly how long these functions have existed.
"The picture we saw now does not mean that it is the same as many millions of years ago," says Wu.
Still, it's an exciting clue that Houser writes in a News and Views article accompanying the study. While parts of the jacket are certainly in an active curvature, "it appears that the lower cap is also a vault-preserving relic of the time when Earth emerged from dust to become a card-bearing planet."