Nonlinear Processes: Russian Geologist on Earthquake Prediction and Earth's Deep Structure

— Roman Vitalyevich, what is known to science today about the deep structures of the Earth, about the speed of rotation of the core of our planet?

- To begin with, the Earth has an outer liquid core and a solid inner core.

Scientists have known for a relatively long time that the solid core rotates faster than the planet's mantle.

But the speed of this rotation - it is called "super rotation" - was very difficult to estimate, because the inner core starts from a depth of 2900 km.

However, in a recent study, scientists from Southern California used new approaches to more accurately estimate the speed of rotation of the inner core relative to the outer shell of the planet.

It was possible to establish that the inner core rotates 0.1 ° per year faster than the outer shells, but most importantly, they for the first time determined the orientation of the core's rotation axis, which used to be compared by default with the Earth's rotation axis, but this turned out to be wrong: the axis rotation of the core is tilted by 8° relative to the axis of rotation of the Earth.

— How have scientists' ideas about the deep structure of the earth's interior changed in recent years?

- The foundations of modern ideas about the internal structure of the Earth were laid at the beginning of the twentieth century, with the development of seismology.

The most breakthrough discoveries have recently been made in understanding the composition of the inner shells of the Earth in connection with the active development of geochemistry and petrology, as well as with the emerging opportunities for numerical and physical modeling of physicochemical conditions in the core and mantle of the Earth.

We still know that there is an upper and lower mantle of the Earth, an inner and outer core, but in their structure it is possible to identify new areas that were previously unknown to science.

• Volcanic eruption in Hawaii

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• © Alain Barbezat

One of the most interesting discoveries of the last decade, I would call the discovery of large heterogeneous structures in the lower mantle, which are associated with manifestations of volcanism on the Earth's surface.

If you look closely at the geographical map, you can see that a lot of volcanoes are concentrated in the Pacific Ocean - for example, in the area of ​​the Hawaiian Islands.

On the other side of the Earth, active volcanism is present in eastern Africa.

All of these numerous volcanoes are associated with deep structures that are located in the lower mantle, at a depth of about 2700 km.

This phenomenon is called intraplate magmatism, and its sources are located at the boundary between the mantle and the core.

And this volcanism differs from the volcanism that usually manifests itself at the boundaries of lithospheric plates.

It was possible to learn this thanks to the development of seismic tomography methods, which took place over the past 15-20 years.

 Is there any chance that at some point, with the development of scientific knowledge, it will suddenly become clear that the structure of the Earth is very different from our modern ideas?

- This probability always remains, because so far no one has descended to the earth's core to study it.

As methods improve, we will build more accurate and detailed models.

But we will not be able to know for sure exactly how the deep structure of our planet looks like until we touch it with our own hands, figuratively speaking.

— It is known that the north magnetic pole of the Earth is shifting to the east at a speed of about 55 km per year.

What caused this process?

Does the Earth face a new change of magnetic poles in the foreseeable future, as has already happened in the history of the planet?

— Indeed, the north magnetic pole of the Earth is now shifting faster than, for example, 20 years ago.

However, this is a normal phenomenon, since the Earth's magnetic field is very changeable and reflects the processes occurring in the outer liquid core of the Earth.

It is also known that before the reversal of the planet's magnetic field, the speed of the magnetic poles usually increased.

We know this from the history of the magnetic field of our planet, which is studied by the science of paleomagnetology.

We also know well that not every time the acceleration of the movement of the poles led to an inversion.

So that

it is, of course, impossible to say unequivocally that the magnetic field inversion has begun.

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• © Pete Gardner

Why is this shift happening?

- The fact is that the Earth's magnetic field is generated in the outer liquid core.

And since the change in the parameters of a liquid occurs much faster than in a solid body, the magnetic field also changes its characteristics very quickly.

- How in practice the shift of the Earth's magnetic pole can turn out for people if humanity still inhabits the planet by this moment?

- This question worries a lot of people.

It is believed that the reversal usually occurs within 2-5 thousand years.

Although according to the latest data, this process can be completed within hundreds of years, which is quite fast even by the standards of the change of human generations.

During this reversal of poles, the strength of the Earth's magnetic field drops, the planet becomes more vulnerable to cosmic radiation, the flow of cosmic particles - the solar wind and galactic radiation.

In this regard, the level of background radiation on the Earth's surface may increase.

However, you should not panic, because these deviations are still not critical for the Earth's biosphere.

For example, the radiation background can rise to the level that is now recorded in the subpolar regions of the planet, where it is higher than at the equator.

So the inversion of the poles does not threaten tragic consequences for humanity.

Unless the radio communication will work with interference, as during magnetic storms.

— To what extent do super-deep wells help to explore the bowels of the planet?

For example, in 2012, the Chaivo Z-44 well was drilled on Sakhalin, which surpassed even the Kola superdeep well in length.

What data can be collected with the help of such wells?

— The Chayvo Z-44 well was drilled as part of the development of hydrocarbon deposits.

Its depth is only 1500 meters, but the length is really the largest on Earth - 15 thousand meters.

This well is horizontal.

Therefore, in terms of studying the earth's interior, as far as I know, it did not play a big role.

But the Kola superdeep really turned out to be extremely important for understanding the structure of the upper shells of the Earth, the earth's crust.

What the researchers saw when they lifted material from this well was sometimes radically different from the scientific models and ideas that existed at that time.

Today, wells similar to the Kola Superdeep are not drilled - everything depends on the cost of such projects.

They will not be able to pay off, because they require very expensive industrial equipment.

• Kola Superdeep Well

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• © A. Varfolomeev

- The thinnest of all is the crust of the Earth under the ocean, in the region of 3-7 km.

How realistic is it to get to the earth's mantle if you drill a well in the ocean floor?

“In general, we already know what the Earth’s mantle looks like, you can even touch it with your hands if you go to the Urals or Cyprus, for example.

In these areas there are geological formations - ophiolites.

In fact, this is the oceanic crust of the Earth, pushed over the land at one time.

In ophiolites one can observe mantle rocks that were once located at a depth of 5-8 km.

Therefore, scientists have a good idea of ​​what the upper horizons of our planet's mantle consist of.

I note that if we drill where the thinnest crust is at the bottom of the ocean, then there we will encounter the largest geothermal gradient.

This means that as you go deeper into the well, the temperature will rise rapidly.

Although there are projects for drilling at ocean depths, they are not aimed at creating very deep wells.

Of interest are geological deposits that can be found at great depths - for example, in the Mariana Trench.

- Geothermal energy - the use of the temperatures of the planet's interior to generate electricity, although it exists in some countries, but in general it is not developing very actively.

Why?

— Geothermal energy is used in those regions where it is expedient.

For example, many geothermal stations operate in Iceland, and there are such stations in Kamchatka.

However, you need to understand that not everywhere geothermal energy is available for use.

The geothermal gradient is different everywhere.

For example, if we drill a well in Moscow for energy, the temperature in it will rise at a rate of 10°C per km.

This means that in order to simply boil water, we will have to drill a well 10 km deep.

But in Kamchatka, the temperature rises by about 50-70°C per km.

And in order to heat the water to a boiling state, we need to drill only a little more than a kilometer - this is already profitable and expedient.

• Geyser

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— Can such works really provoke earthquakes?

If so, doesn't this apply equally to gas and oil production by hydraulic fracturing?

- As far as I know, it is impossible to provoke large earthquakes using the hydraulic fracturing method, or by drilling wells.

The fact is that large earthquakes are caused only by the movement of lithospheric plates, tectonic phenomena.

Fortunately, a person is not capable of causing them artificially.

Although hydraulic fracturing can indeed cause small fluctuations in the upper horizons of the earth's crust, but here we are talking about such activity that only seismometers can record, but a person is unlikely to be able to notice it.

- There is a hypothesis according to which the seismic activity of the Earth, as well as other geological processes, can be influenced by solar activity, solar flares.

Is this theory confirmed?

- As for solar flares, I doubt that they can somehow affect terrestrial seismic activity.

However, the gravitational interaction of the Earth with other cosmic bodies, including the Sun, can exert such an influence.

Of course, today this impact is not very strong, and can hardly be the main cause of earthquakes and volcanic activity.

However, it should be recalled that when the Moon passes near our planet, not only the water level in the ocean rises, but also the land level by several centimeters.

And four billion years ago, when the Moon was closer to the Earth, this tidal hump of the earth's firmament was several kilometers.

- Do supervolcanoes, such as Yellowstone, come from a real threat to humanity?

- Of course, the eruption of supervolcanoes is very dangerous, because it will not only lead to the death of many living organisms, but also change the Earth's climate.

The result will be either a cooling, or, conversely, an increase in the greenhouse effect and warming.

Fortunately, such eruptions are extremely rare, so that humanity has a chance not to catch such a catastrophe.

• Yellowstone National Park, USA

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• © Dukas / Christian Heeb / Universal Images Group

- How accurate is it possible to predict the eruption of both ordinary volcanoes and supervolcanoes in our time?

Is there a risk that the eruption will take people by surprise?

How have the methods of predicting eruptions and earthquakes advanced in recent years and decades?

- If we talk, for example, about the Yellowstone supervolcano, then it is still alive, there are many manifestations of thermal activity in its area.

Volcanic activity continues, albeit in a subdued format.

And when a new super-eruption will occur, no one knows.

More or less reliable can only be a short-term forecast, when magma will already be moving in the earth's crust.

Such a forecast can be made a few hours, maybe days before the magma begins to come to the surface.

This may be enough to evacuate people from the vicinity of the volcano.

But all volcanoes are different, so it would be wrong to say that about all volcanoes.

It is impossible to predict the eruption in a month, even in two weeks with high accuracy.

As in the case of weather forecasts, in this case we are dealing with non-linear processes that are difficult to model.

Of course, scientists are working to make these predictions more long-term and more accurate.

Methods, equipment are being improved, and in addition, we are learning more and more about the past of the Earth.

And this gives science a more reliable foundation for making such predictions.