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Giant mountains discovered inside the Earth

Giant mountains discovered inside the Earth 86

Studying the boundary between the Earth’s core and mantle, geophysicists have found that it is not as smooth as previously thought. Surfaces separating the inner layers also have a complex relief. It turns out that our planet is not at all like a set of spheres nested into each other, as is customary to portray it.

Reading the waves. Earth’s crust

The deep bowels of geophysics are judged by seismic waves generated by earthquakes. There are longitudinal P-waves – when elastic mechanical vibrations occur along the propagation direction and transverse S-waves – the vibrations in them are perpendicular.At the boundary of layers with different densities, the wave velocity changes dramatically. In the transition from a solid crust to a more plastic upper mantle, it increases. This border is called the surface of Mokhorovichich. The lower mantle is harder than the upper. The outer core, in which transverse seismic waves do not propagate, is liquid, and the inner core is again solid, but slightly plastic.

While the network of seismographs was rare, the sections between the inner shells with a certain degree of conventionality were depicted as spheres. As the data accumulated, it became clear that each of these boundaries is a complex surface with its relief and internal “mountains” even higher than on the Earth’s surface, and the “troughs” are deeper. From the top of Everest to the bottom of the Mariana Trench about 20 kilometers, and, for example, the differences of the border of Mokhorovichich, dividing the crust and upper mantle, reach 40 kilometers. And all this at a depth of five to 70 kilometers.

This was proved by scientists from China and the United States . They analyzed the results of observations of hundreds of seismic stations obtained from the same events: the earthquakes in Bolivia of 1994 and the Sea of ​​Okhotsk in 2008 and 2012, as well as archival records of seismographs of the National Center for Information on Earthquakes of the US Geological Survey.

The authors of the study found that for the boundary between the upper and lower mantle, located at a depth of about 660-670 kilometers, the data of the various stations almost completely coincide. That is, she has a stable relief, which she even managed to map. Signal processing of the Bolivian earthquake made it possible to literally create a “topographic map” of the surface of the lower mantle for an entire region in Southeast Asia .

The most dynamic area. Mantle and core

When talking about the dynamics of the Earth, they usually mean large-scale surface processes associated with the movement of lithospheric plates. In the zones of mid-ocean ridges and rifts, the lithosphere moves apart, and in subduction zones on the outskirts of the continents, oceanic plates sink under the continental.

But no less dynamic processes and surface movements occur inside the Earth – only their reflection. First of all, we are talking about mantle convection, which arises due to the temperature difference in the bowels and on the surface of the planet. 

Upward flows of convection cells stretch the lithosphere, downward flows drag it into the mantle. Moreover, in the upper parts of the cells, the substance flows in a horizontal plane and these flows cause lithospheric plates to move.The most dynamic region of the Earth is located on the border of the core and mantle, at a depth of about 2900 kilometers.

It is believed that its heterogeneity affects many geological processes, in particular, the oscillation of the axis of rotation of the Earth and the characteristics of the geomagnetic field. In addition, convection itself is a consequence of what happens in the D ”layer at the boundary with the core.On its surface, scientists discovered arrays of unusually dense, hot rocks – zones of abnormally low seismic wave velocities (ULVZ – Ultra-low velocity zones). They stretch for hundreds of kilometers, and their “height” – tens of kilometers.Above them are hot spots with volcanoes: Hawaiian, Marquesas, Galapagos Islands and the Samoa archipelago in the Pacific Ocean, Canary Islands and Azores , Iceland in the Atlantic, Kerguelen archipelago in the Indian, Afar volcanism zone in the Great African Rift.

Using the new machine learning algorithm, American scientists at Johns Hopkins University and the University of Maryland at College Park together with their Israeli colleagues from Tel Aviv University performed a parallel analysis of seven thousand seismograms covering hundreds of earthquakes from 1990 to 2018, and for the first time compiled a detailed section map the core and mantle of the Pacific region, on which all ULVZ zones were applied.It turned out that ULVZ are only separate protrusions within the larger, low-shear-velocity provinces (LLSVP) provinces, which are also called superplumes. Their branches penetrate up into the mantle for thousands of kilometers. Now scientists distinguish two such provinces – African and Pacific.

Superplumes (provinces with a low shear rate) at the boundary of the core and mantle look like they look from the North (a) and South (b) poles.  The center shows the core of the Earth with the projection onto it of the contours of the continents;  outer contour - conditional border of the lower mantle
© Sanne Cottaar, Vedran Lekic / Geophysical Journal International, 2016Superplumes (provinces with a low shear rate) at the boundary of the core and mantle look like they look from the North (a) and South (b) poles. The center shows the core of the Earth with the projection onto it of the contours of the continents; outer contour – conditional border of the lower mantle

The circulation of matter in the mantle

Australian scientists from the University of Curtin suggested that the periods when all the land of the Earth united into single supercontinents – Pangea, Rodinia, Colombia and others, coincided with activity in the deep LLSVP provinces. They built a dynamic model linking the evolution of superplumes to the assembly and decay of supercontinent. According to this model, LLSVP arrays are formed from lithospheric plates, which, as it turned out, sinking, does not dissolve in the mantle, as previously thought, but descend to the very boundary of the core. Here they melt, and giant drops of preheated matter – mantle plumes – coming off from LLSVP, float to the surface, giving rise to a new geodynamic cycle. The lithosphere rises above the plumes, forming a dome, and then cracks and diverges.

Inside the core

Researchers from the US and China have analyzed how seismic waves passing through the boundary between the outer and inner core change. For this, we used signals from doublets – repeated earthquakes with the same epicenter.

It turned out that these changes have a certain periodicity, which can be explained by two mechanisms: either the inner core rotates by about 0.05-0.1 degrees per year, or high “mountains” and deep “canyons” appear on its surface. So, a dynamically changing relief can also be at the deepest boundary between the earth’s shells.


Planet Earth

Polar vortex: “wild” winter is coming in the US, Northern Europe and East Asia after the 16th of January

Polar vortex: "wild" winter is coming in the US, Northern Europe and East Asia after the 16th of January 89

In the upper atmosphere above the North Pole, experts saw a rapidly swirling vortex of cold air that could bring severe frosts to the United States, Northern Europe and East Asia. Serious cold snap and snowy weather are expected after January the 16th.

Snowfalls and a cold snap hit South Korea since the start of 2021, hitting historic snow maximums and temperatures. In the country, for the first time since 1964, television and newer communications are sending people cold snap warnings:

The situation is similar in Japan, where a new snow storm hit historic highs:

On January 7, the thermometer In Beijing dropped to -20 degrees Celsius, breaking the 1966 record. In other regions of China, the temperature is also not sugar, and you can only move around in special uniforms:

The cold even reached Taiwan, where the temperature in some areas dropped below freezing point, snow poured down and people realized that rice terraces can be used as a ski jump:

Even more snow went to Spain, where on January 6, 2021, a temperature of -34.1 ° C was recorded – the lowest on record. After that, a snow storm hit the country, which has not been seen for 80 years:

The same thing happens in Canada and in the northern states of the United States:

It seems that after a stratospheric warming, the subpolar vortex began to split:

The vortex itself is a standard phenomenon. However, this time experts were surprised at his movement. It is possible that in the near future it will be divided into two parts. 

Scientists associate the strange behavior with the changed climate in the Arctic, which has become warmer. From September to December, the amount of ice cover decreased significantly.

The polar vortex is a low-pressure region located in the stratosphere and filled with cold air. When the jet stream of air that holds the vortex weakens, the low pressure area moves south. 

As the ice shrinks, more moisture will move inland. It will turn to snow, so snowfalls are expected. Snow, in turn, reflects heat, leading to a cold snap.

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Planet Earth

Hospital in Naples was evacuated after a new, huge sinkhole appeared

Hospital in Naples was evacuated after a new, huge sinkhole appeared 90

Eyewitnesses said they heard a loud crash at dawn when a huge hole in the ground formed outside the Ponticelli Ospedale del Mare hospital in eastern Naples.

Early in the morning of January 8, 2021, a sinkhole occurred in the parking lot of a clinic in Naples. The depth of the formed cavity is about 20 meters, the total area of ​​the hole is about 2,000 square meters.

No casualties were found at the scene; firefighters say the sinkhole “affected an area of ​​about 500 square meters” and engulfed several cars parked near the hospital.

As the press writes and as a little can be seen from the videos, rescuers and firefighters were running around the pit together with the governor of the area.  But who should be there in the forefront are Italian geologists, since Naples stands in the very center of the volcanic system known as the Phlegrean Fields.

If the surface collapsed, moreover – the surface reinforced with concrete and reinforced from below with some kind of communications, then we are talking about serious soil deformations caused by the activity of magma.

Italy has been in doubt since the summer of 2020, because swarms were observed there in very atypical places in May, and according to the forecasts of old Italian seismologists, who had witnessed many strong earthquakes, it should have boomed in the August region.

Fortunately, nothing bad happened to Italy and there was no big earthquake. But, since there are swarms, it means that something is being prepared, the magma is gathering strength. 

Following this particular sinkhole event – an obvious sign that a major earthquake in Italy is already very close.

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Planet Earth

A new great pandemic cycle has begun (again) in China

A new great pandemic cycle has begun (again) in China 91

In the first months of 2020, the whole world with a certain fright followed the events unfolding in China, where people fell on the streets during the day and astronauts wandered, and in the evening crematoria began to smoke. And now, with the onset of December, the cycle seems to be repeating itself.

Shunyi area in Beijing, where the authorities announced “wartime status” the day before. As you can see in the videos, thousands of people are lined up in the queue for mandatory testing:

Dalian city, where “wartime” is also declared. Neighborhoods are blockaded, people are walled up in entrances, familiar characters of George Lucas roam the streets:

Chinese ‘rescuers’, before performing a combat mission:

Chengdu City:

Daluo Port, Yunnan – tourists came for adventure and they received the ‘time of their life’ after leaving the ramp:

If something happens in Beijing, it does not mean that tomorrow the same will happen everywhere. However, the trend towards such dynamics is observed and, as the practice of the first wave of the pandemic has shown, all countries and people, to one degree or another, have taken into account the ‘Chinese experience’. 

Therefore, one must think that everything will now be in peace, as in spring – a new global round of the fight against the Covid has begun in China, a new great pandemic cycle!

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