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Volcanoes that do not show volcanic activity. Volcanoes and volcanic activity

In the media and in some scientific publications, various statements disturbing people began to appear about the approach of some kind of global geological catastrophe.

The press service of the World Organization for Scientific Cooperation "Science without Borders" (WOSCO SWB) asked to comment on the situation of a well-known scientist - geophysicist, specialist in seismology and geodynamics, Vice-President of the H&E International Academy of Sciences (Austria, Innsbruck), Academician of the Russian Academy of Natural Sciences , Doctor of Geological and Mineralogical Sciences, Director of the Research Institute for Forecasting and Studying Earthquakes Elchin Khalilova.

Dear Professor Khalilov, recently a lot of information has appeared in the media about the approach of a global natural disaster. Some attribute this to the possibility of a so-called polarity reversal or reversal of the sign of the north and south magnetic poles of the Earth, others predict catastrophic climate change and global flooding of vast land areas, others predict earthquakes, volcanic eruptions and tsunamis of incredible power. Other forecasts are based on the possibility of a huge asteroid passing near the Earth's orbit, which, by gravitational influence, can cause global natural disasters on Earth. What to really believe? Please comment on this situation.

I have been studying seismic and volcanic activity from the point of view of global geodynamic processes for over 25 years. All these years, research has been carried out by me together with an outstanding scientist of our time, a world-famous Russian geologist, academician of the USSR Academy of Sciences, the Russian Academy of Sciences and many national and international academies, Honorary President of the International Academy of Sciences (health and ecology), Honored Professor of Moscow State University named after M.V. Lomonosov Viktor Efimovich Khain. But I want to emphasize that everything I have said is based on our many years of joint research.

First of all, I would like to note that many of the disturbing factors that you mentioned do exist, but perhaps they are not always correctly interpreted. The fact is that the research carried out by us together with famous scientists, academicians V.Khain, Sh.Mehtiyev and T.Ismailzade, made it possible for the first time to establish an unusual modern cyclicity in the manifestations of earthquakes and volcanic eruptions of our planet. It has long been noted that at certain periods of time, as if, on a special command, strong earthquakes and volcanoes erupt almost simultaneously in various parts of the planet, then a lull also suddenly sets in.

In fact, research results have shown that this cyclicity in the manifestations of strong earthquakes and volcanic eruptions is not at all simple. In particular, it turned out that while earthquakes and volcanic eruptions are activated in some zones (in the Earth's compression belts), in other zones they subside (in the Earth's extension belts), then the reverse process occurs, seismic and volcanic activity in the Earth's compression belts. decreases and increases activity in the Earth's stretch zones.

For geologists, it is obvious that earthquakes and volcanoes are an excellent indicator of tectonic activity on the planet. That is, if earthquakes of the Earth's compression belts are activated, this means that the compression processes on the planet have intensified, if activation occurs in the Earth's extension zones, it means that the extension processes are intensifying.

The results of our research were recognized as a scientific discovery in 2003.

- What comes from this and where are the zones of compression and extension of the Earth?

The Earth's compression and extension belts are planetary, relatively narrow and gigantic areas of volcanic and seismic activity, in which more than 80% of the energy of earthquakes and volcanic eruptions of the world is released. For a better understanding, without going into the wilds of geology, I will explain that the uppermost shell of our planet is divided into giant blocks that move horizontally relative to each other. They are called lithospheric plates. So, almost all the strong earthquakes and volcanoes of the world are concentrated on the boundaries of these plates. Where the plates diverge, the Earth's lithosphere stretches, and where they collide, compression processes occur.

Almost along the central axis of the entire world ocean there are oceanic rift zones - giant faults that reflect the boundaries of the lithospheric plates, where they diverge.

It is here that the Earth's lithosphere undergoes stretching and renewal. In some places, these zones also originate on the continents, for example, a giant rift zone runs in the meridional direction along the Eastern part of Africa, in the zone of Lake Baikal, through Iceland.

The belts of compression of the Earth are mainly giant mountain systems, and in the oceans - deep-sea depressions and ridges of islands bordering them, often of volcanic origin. Classic giant belts of compression of the Earth are mountain ranges that run along the western part of the continents of Northern and South America, Alpine-Himalayan seismic belt - a mountain range starting from the Alps and reaching the Himalayas, capturing part of China and India. The Alpine-Himalayan seismic belt includes some countries of the Middle and Near East, countries of Southern and Southeastern Europe, the Caucasus, Central Asia and part of Southeast Asia.

If we talk about the young and, perhaps, the most active belts of compression of the Earth, then these are mainly the countries of the so-called ring of fire.

The "Ring of Fire" is a horseshoe-shaped band of volcanoes and tectonic faults 40 thousand kilometers long, encircling the Pacific Ocean, running along the coast of the South and North America to the southern part of Alaska, then turning towards Japan (including the Russian Far East), the Philippines and Indonesia and ending in the area of ​​the island of New Guinea, New Zealand and southwestern Oceania. It is in the "Ring of Fire" that more than 80% of the approximately one and a half thousand known active volcanoes of the planet are located.

For a better understanding, we have shown a map on which all the zones I have indicated are indicated.

- What can we expect in the near future in the regions you mentioned?

I really want to reassure readers, to say that no increase in seismic and volcanic activity is expected, which I have repeatedly done in many of my statements in the past years. But, unfortunately, I cannot do this now, since it is my duty as a scientist to provide objective information to society, to try to predict the further development of events. In fact, this is the main point of seismology and volcanology, otherwise why do you need to do these studies.

Now it has already become obvious that the Earth should be considered as an integral element of the cosmos, inextricably linked with the processes taking place in it. The famous Russian scientist A.L. Chizhevsky, back in the 20s of the last century, devoted a lot scientific works study of the influence of solar activity on terrestrial processes of a biological, socio-psychological and geological nature.

Many scientists of the world confirm the fact of the influence of the activity of the Sun on the activation of earthquakes and volcanic eruptions, but nevertheless, some ambiguity is felt in these results. In our research with the participation of academicians V. Khain and Sh. Mehdiyev, we managed to discover new aspects in this matter. So it turned out that solar activity differently affects the activation of earthquakes and volcanic eruptions in different regions of our planet. For example, with an increase in solar activity, the activity of earthquakes and volcanic eruptions in the Earth's compression belts increases, while in the extension belts, on the contrary, it decreases.

Moreover, what is especially important, the higher the amplitude of the solar activity cycle, the higher the seismic and volcanic activity.

At the same time, the non-simultaneity of the planetary processes of compression and extension indicates the possibility of periodic changes in the Earth's radius within a few centimeters, which, in our opinion, is reflected in changes in the angular velocity of its rotation.

The most pronounced cycle of solar activity is the 11-year cycle. Since the start of regular observation of sunspots, 23 cycles of solar activity have been officially registered, with the 23rd cycle occurring in 2001. Surely experts remember that from the end of 1999 to 2004 there were many catastrophic earthquakes that claimed more than half a million lives. The year 2007 can be called the year of minimum solar activity, but since 2008 it has begun to rise again. It would seem, well, what's unusual here, they survived 23 cycles before that, well, another one will pass. Unfortunately, the 24th cycle is predicted to be not quite usual.

For any forecasts, first of all, process models are created. The most accurate model for the origin of sunspots was developed in 2004 by a team of scientists working under the leadership of Dr. Mausumi Dikpati from the US National Center for Atmospheric Research (NCAR). According to their calculations, the magnetic structures that form spots originate in the region of the Sun's equator. There they are “imprinted” into the plasma and together with it move towards the poles. Having reached the pole, the plasma plunges into the interior of the star to a depth of about 200,000 km. From there, it begins to flow back towards the equator at a speed of 1 m/sec. One such circle corresponds to the cycle of solar activity - 17–22 years. The researchers called their model the “magnetic flux dynamo transport model”. We are now at the beginning of the 24th 11 year solar cycle. Putting data on the 22 preceding the 23rd cycle into the model, the scientists calculated what the 23rd cycle should be. The result coincided with what we observe by 98%. Having thus tested their model, the researchers in early 2006 calculated the 24th cycle of solar activity, which will peak in 2012.

It is predicted that the 24th cycle of solar activity will be 1.5 times more powerful than the previous 23rd. And this means that the number and energy of earthquakes and volcanic eruptions during this period will be significantly higher than all previous ones. In addition, we have established that during this period the maxima of the cycles of solar activity, at least three orders of magnitude, will coincide, which should lead to a kind of energy resonance.

Our studies have shown that there is some inertia in the increase in seismic and volcanic activity, in relation to the solar one. That is, if the peak of solar activity falls on the year 2012, then the maximum seismic and volcanic activity will fall on 2012-2015. I would like to especially emphasize that this conclusion is also confirmed by the cyclical activity of earthquakes and volcanic eruptions of the compression belts of our planet, which peaks also fall on this period, which we have established. In a word, from 2012 to 2015 our planet will be, to put it mildly, “hot”.

- Which countries, in your opinion, will be the most affected? natural disasters?

I'll start, first of all, with the "ring of fire" - I listed the regions included in this zone above. The ring of fire will live up to its name, because it is there that the largest number of the largest active volcanoes in the world is located.

The strongest earthquakes will also occur there. In second place in terms of seismic activity (but not volcanic) I would put the Alpine-Himalayan seismic belt, and in it, the most dangerous territories are in the northwestern part of India, China, Pakistan and Afghanistan, the southern part of the republics Central Asia, Iran, Caucasian countries, Turkey, Italy, Greece. In Italy, there is also a high probability of triggering, during the noted period, the volcanoes Etna and Vesuvius on its territory. Along with the indicated territories, an increase in seismic activity along the entire western coast of North and South America is expected at a similar level.

- You have listed so many territories that it becomes creepy. Where, after all, will it not shake so much?

Of course, there are many areas that will not be affected by seismic and volcanic activity - these are the so-called intra-plate zones or platforms.

For example, this is the entire central and northern part of Russia, the eastern part of Scandinavia, the central and northern parts of Europe, Australia, Greenland, the entire western part of the African continent, the eastern part of South and North America and the entire northern part of North America. So, you can certainly move into these zones. But I want to warn you that some of them may be subjected to natural disasters of a different nature.

- Nu that you take away the last hope? What other surprises does nature have in store for us?

I want to remind you that at the beginning of our conversation you mentioned disturbing information regarding the possible reversal of signs of the Earth's magnetic poles.

So, I would like to dwell on this in a little more detail. The fact is that many often identify the magnetic and geographic poles of the Earth. But in fact, these are completely different concepts and their location does not match.

The geomagnetic field is not so constant and it changes from time to time.

The role of the geomagnetic field for the existence and development of life on Earth can hardly be overestimated, because the lines of force of the Earth's magnetic field create a kind of magnetic screen around the planet that protects the Earth's surface from destructive, for all living things, cosmic rays and the flow of high-energy charged particles.

The latest data on the state of the Arctic magnetic pole (moving towards the East Siberian world magnetic anomaly through the Arctic Ocean) showed that at the beginning of 2002, the drift rate of the north magnetic pole increased from 10 km / year in the 70s to 40 km/year in 2001.

In addition, according to IZMIRAN data (Russia, Moscow), there is a drop in the strength of the earth's magnetic field, and very unevenly. According to scientists from IZMIRAN, the acceleration of the movement of the poles (by an average of 3 km/year) and their movement along the corridors of magnetic pole reversal (more than 400 paleoinversions made it possible to identify these corridors) leads to the assumption that this movement of the poles should not be seen as an excursion , but the polarity reversal of the Earth's magnetic field.

In 2007, the Danish Space Research Center, after analyzing the latest data received from a satellite monitoring the Earth's magnetic fields, came to disappointing conclusions. According to Danish scientists, there is an intensive preparation of the Earth's geomagnetic field for the reversal of the magnetic poles, and this may happen much earlier than expected.

But I would like to emphasize that geophysicists cannot but be disturbed by the fact that the movement of the magnetic poles has accelerated by almost five times over the past four decades. What underlies the movements of the magnetic poles? First of all, these are processes occurring in the core of the Earth. If the magnetic poles moved much faster, then the energy in the Earth's core began to increase significantly. At the same time, as is known, it is the deep energy processes in the Earth's core that set in motion giant convective flows in the mantle, which, in turn, move lithospheric plates, at the boundaries of which earthquakes and volcanic eruptions occur.

Consequently, a five-fold acceleration of the movement of the magnetic poles indicates that the speed and scale of energy processes in the interior of our planet have increased dramatically, which corresponds to our conclusions about the approach of an unusually high level seismic and volcanic activity.

As for climate change, it will be a consequence of the above processes.

What do you mean by this, that global climate changes will be connected with earthquakes and volcanic eruptions?

You know, in the last decade, a lot of works have been devoted to global climate change, and, in most of them, the main role in global warming is given to man-made human activities. But is it really so?

In our work, we, together with Viktor Efimovich Khain, carried out detailed comparisons of the graphs of the volcanic activity cycles over the past 150 years and the average annual temperature changes on our planet. So, the result exceeded all our expectations. Firstly, the graphs almost repeat each other in form and periods of cycles. But, on the other hand, the cycles on the temperature increase graph are about 15 years late in relation to the cycles of increasing volcanic activity. This delay is based on a causal relationship between these two processes.

What is the mechanism of causal relationship between volcanic activity and temperature changes on Earth? An increase in the number of volcanic eruptions leads to an increase in the release of volcanic gases into the atmosphere, contributing to an increase in greenhouse effect and, as a consequence, leading to an increase in the temperature of the atmosphere. From 1860 to 2000, the number of volcanic eruptions increased by 80%.

An almost doubling of the average annual number of volcanic eruptions should lead to a doubling of volcanic gases entering the atmosphere, primarily CO2, which plays a leading role in the formation of the greenhouse effect and an increase in the average annual temperature on Earth.

Based on the regularities we have established, an attempt was made to make a long-term forecast of both changes in the volcanic activity of the Earth's compression belts and global changes in the average temperature on our planet until 2060.

The global increase in the average annual temperature on Earth, against the background of minor variations, according to the results of our research, will be observed from 2020 to 2050.

An increase in the average annual temperature, of course, will be accompanied by the melting of ice, an increase in the level of the world's oceans and precipitation on the Earth.

Do you want to say that even if people save themselves from earthquakes and volcanic eruptions, they will be overtaken by another misfortune - the global flooding of giant land areas?

I would not like to be unfounded, so I will resort to the official data of the Intergovernmental Commission on Climate Change (IPCC) http://www.ipcc.ch/ As follows from the reports of this commission, "greenhouse" warming is coming, as a result of which some ice sheets and ocean levels will rise by 5-7 m in just decades. It will be a truly global catastrophe: entire countries (for example, Holland), Largest cities world - New York, Tokyo, St. Petersburg, etc. - will be under water (IPCC, 2007).

The difference between our conclusions and the IPCC commission is only in assessing the scale of the geological factor in global warming. If the commission assigns the main role to man-made human activity, then we believe that the role of natural processes is much higher. In our opinion, it is impossible to single out global climate changes in a separate independent channel in isolation from the general context of the geological development of the Earth.

True, this does not make it any easier for people. Although, perhaps the realization that not so much human civilization as nature is to blame for all this, somewhat reduces our sense of guilt towards future generations.

Are you saying that the end of the world is coming?

Of course not - this is not the end of the world, but this is one of the most difficult stages in the life of human civilization. During this period, we should expect a large number of human casualties, exacerbation of the global economic crisis, destructuring of systems government controlled and international coordination of action. But in certain regions it will be relatively calm and these territories can be determined in advance in order to prepare the appropriate infrastructure for them in advance.

You predict a difficult fate for entire generations, but do you and Academician Viktor Efimovich Khain have any proposals, if not for prevention, then at least for some reduction in the catastrophic consequences of impending cataclysms?

Of course there are, and I'll list them here:

· First of all, it is necessary to adopt the United Nations Framework Convention on Global Natural Disasters, following the example of the adoption in 1992 of the United Nations Framework Convention on Climate Change (UNFCCC), in response to the emergence of increasing scientific evidence that global climate change is determined by anthropogenic changes in the content of greenhouse gases. atmospheric gases.

· At the second stage, it is necessary to create a special International Intergovernmental Commission under the UN, following the example of the Intergovernmental Commission on Climate Change (IPCC), with the inclusion in its composition of a special expert group that brings together the world's leading scientists in the fields of seismology, volcanology, geodynamics, climatology, meteorology, hydrology, etc. .

· At the third stage, it is necessary, on an urgent basis, to develop and approve the UN International Program for the study and forecasting of the development of the seismic and volcanic situation in conjunction with global climate change.

· The last and final stage of this process should be the creation of a single international financial fund and financial mechanism for preparing humanity for possible global natural disasters on a planetary scale. This stage will also include the identification of the most stable and safe territories on our planet and the creation of special infrastructure on them for the accommodation and life support of a large number of refugees who will become the basis for the emergence of new centers of human civilization.

In conclusion, I would like to emphasize that only by combining our efforts, economic, technical and human resources, regardless of race, culture and religion, human civilization will be able to cross the great threshold that nature has prepared for it. It is this stage of her life that will give rise to the creation of a new formation. human society with a whole new positive mindset.

Thank you very much for such a detailed, scientifically grounded and interesting interview. In conclusion, we would like to clarify where scientists and specialists can get acquainted with the results of your research?

Firstly, I want to inform you that recently, in the international publishing house SWB, our joint monograph with Academician Viktor Efimovich Khain was published: Khain V.E., Khalilov E.N. Spatio-temporal patterns of seismic and volcanic activity. Bourgas, SWB, 2008. ISBN 978-9952-451-00-9

Given the great interest in the problem, in agreement with the S WB publishing house, the book is placed for free use in the International Scientific Electronic Library of the World Organization for Scientific Cooperation - WOSCO Science Without Borders: www.wosco.org, as well as on the website: www.khalilov.biz

But some of the issues raised in the interview can be found right now in the articles:

V.E.Khain, E.N.Khalilov. ON THE POSSIBLE INFLUENCE OF SOLAR ACTIVITY ON SEISMIC AND VOLCANIC ACTIVITY: LONG-TERM FORECAST

V.E.Khain, E.N.Khalilov. GLOBAL CLIMATE CHANGE AND THE CYCLE OF VOLCANIC ACTIVITY

Sedimentary layers contain far fewer traces of volcanic activity than would be expected from geological history, which, according to scientists, is billions of years old. Volcanic emissions include lava, ash, cinders, and more. Eruptions are minor, and may be large, accompanied by emissions of many cubic kilometers of rock. A few years ago, a geologist, based on the rather conservative estimate that all the world's volcanoes eject an average of one cubic kilometer of volcanic material per year, calculated that in 3.5 billion years the entire Earth should have been covered with a seven-kilometer layer of such material. Since in fact its proportion is quite small, the scientist concluded that the intensity of volcanic activity must fluctuate 22 .

Currently, terrestrial volcanoes eject, apparently, about four cubic kilometers of material per year. Individual large eruption may be accompanied by significant emissions. Volcano Tambora (Indonesia, 1815) erupted 100-300 cubic kilometers; volcano Krakatau (Indonesia, 1883) - 6-18 cubic kilometers; and the volcano Katmai (Alaska, 1912) - 20 cubic kilometers 23 . Estimates that include only major volcanic eruptions over four decades (1940-1980) show an average of 3 cubic kilometers per year 24 . This estimate does not take into account the many smaller eruptions that periodically occur in regions such as Hawaii, Indonesia, Central and South America, Iceland, Italy, etc. Experts say that the average volume of volcanic emissions is 4 cubic kilometers per year 25 .

According to the classic work of the famous Russian geochemist A.B. Ronova, the Earth's surface contains 135 million cubic kilometers of sediments of volcanic origin, which, according to his estimates, is 14.4 percent of the total volume of sedimentary rocks 26 . Although the figure of 135 million sounds impressive, it is not much compared to the amount of sedimentary rocks that would have to be deposited as a result of volcanic activity over long geological epochs. If current emission rates are extrapolated to 2.5 billion years, then the Earth's crust should contain 74 times more volcanic material than is currently available. The thickness of this volcanic layer, covering the entire earth's surface, would exceed 19 kilometers. The absence of such volumes can hardly be explained by erosion, since it would only carry the products of volcanic eruptions from one place to another. It can also be assumed that a huge amount of volcanic material disappeared as a result of subduction, which is suggested by plate tectonics, but this explanation also does not hold water. Along with the volcanic material, other geological layers containing it would also disappear. However, the geologic column that includes this volcanic material is still clearly visible throughout the world. Perhaps volcanic activity is still not 2.5 billion years old.

RISE OF MOUNTAIN RANGE

The so-called solid ground that we prefer to have under our feet is not as unshakable as we think. Careful measurements show that parts of the continents are slowly rising while others are sinking. The major mountain ranges of the world are slowly rising at a rate of a few millimeters per year. Precise measurement techniques are used to determine this growth. Scientists estimate that, in general, mountains rise by about 7.6 millimeters per year 27 . The Alps in Central Switzerland grow more slowly - from 1 to 1.5 millimeters per year 28 . Studies show that for the Appalachians the rate of uplift is 0-10 millimeters per year, and for the Rocky Mountains it is 1-10 millimeters per year 29 .

I am not aware of any data regarding accurate measurements of the rate of uplift of the Himalayas, however, due to the fact that relatively recent tropical vegetation and the fossilized remains of a rhinoceros were found at an altitude of 5000 meters, as well as on the basis of overturned layers, scientists conclude that uplift rates equal to 1-5 millimeters per year (under uniform conditions over long epochs). It is also believed that Tibet is rising at about the same rate. Based on mountain structure and erosion data, researchers estimate the rate of uplift of the Central Andes at about 3 millimeters per year 30 . Parts of the Southern Alps in New Zealand are rising at a rate of 17 millimeters per year 31 . Probably the fastest gradual (not associated with catastrophic events) mountain growth is observed in Japan, where researchers note the rate of uplift of 72 millimeters per year over a 27-year period 32 .

It is impossible to extrapolate the current rapid rate of uplift of mountains to a too distant past. At an average growth rate of 5 millimeters per year, mountain ranges would rise 500 kilometers up in just 100 million years.

It will not help us to resolve this discrepancy and the reference to erosion. The rate of uplift (about 5 millimeters per year) is more than 100 times the average rate of erosion that scientists estimate existed before the advent of agriculture (about 0.03 millimeters per year). As stated earlier, erosion is faster in mountainous areas, and its rate gradually decreases as the terrain lowers; therefore, the higher the mountains, the faster they erode. However, according to some calculations, in order for erosion to keep up with the so-called "typical uplift rate" of 10 millimeters per year, the height of the mountain must be at least 45 kilometers 33 . It is five times higher than Everest. The problem of discrepancy between the rate of erosion and the rate of uplift does not go unnoticed by researchers 34 . In their opinion, this contradiction is explained by the fact that at present we are witnessing a period of unusually intense uplift of mountains (something like episodic).

Another problem for standard geochronology is that if mountains have been rising at their current rate (or even significantly slower) throughout the history of the Earth, then the geological column, including its lower layers, which, according to geologists, are hundreds of millions, if not billions of years, should have risen and vanished long ago through erosion. However, all the ancient sections of the core, as well as the younger ones, are well represented in the geological record of the continents. The mountains, where unusually high rates of uplift and erosion are observed, apparently did not go through even one cycle including these processes, although there could be at least a hundred such cycles throughout all hypothetical epochs.

CONCLUSION

The observed rates of erosion, volcanism and uplift of mountain ranges are perhaps too high for the standard scale of geological time, which takes billions of years for the formation of sedimentary layers and the evolution of the life forms represented in them. The discrepancies are very significant (see Table 15.3), and therefore they cannot be neglected. Hardly any scientist can guarantee that the conditions that existed on Earth in the past remained constant enough to ensure the same rate of change over billions of years. These changes could have gone faster or slower, but the numbers in Table 15.3 show how big the discrepancies are when we compare their current rates with the geologic time scale. Geologists put forward various explanations in an attempt to reconcile these data, but their hypotheses are largely based on conjecture.

On the other hand, it could just as well be argued that many of the above processes are too slow for the creation model, according to which the earth is less than 10,000 years old. However, this argument does not carry much weight, since the creation model includes a catastrophic, global flood that can greatly increase the rate of each of these processes. Unfortunately, our knowledge of this unique event is too poor for us to make any serious calculations, but recent trends in geological science towards catastrophic interpretations allow us to judge how quickly such changes could occur 35 .

Factors contrary to standard geochronology Table 15.3

One can try to reconcile the current high rates of change with geologic time, assuming that in the past these rates were lower, or they were distinguished by cyclicity. However, calculations show that individual processes should have proceeded tens and hundreds of times slower than now. And this is hardly possible, given the fact that the Earth of the past was not very different from the Earth of the present, as evidenced by the animal and plant species found in the fossil record. Fossil forests, for example, needed significant moisture, just like their modern counterparts. In addition, slower changes in the past seem to contradict the general geological scenario, according to which the Earth was more active at the beginning of its history 36 . Geologists believe that at that time the heat flow and volcanic activity were much larger. Is it possible for evolutionary scientists to turn this model on its head and claim that change is happening much faster now? Unfortunately, this trend is completely at odds with what we might expect from an evolutionary model. This model assumes an initially hot Earth cooling down to a more stable state, as well as rates of geological change slowly decreasing over time towards equilibrium.

When we look at the current rate of erosion and uplift of mountains, the same question periodically arises: why is the geological column so well preserved if such processes take place over billions of years. However, the current rate of geological change is easily written off as a recent creation and subsequent catastrophic flood. The retreating flood waters must have left behind significant parts of the geological column in the form in which they remain to this day. In the context of the Flood, the relatively low rates of erosion, volcanism, and uplift of mountain ranges that we now observe may represent the lingering consequences of that catastrophic event.

The current intensity of geological transformations calls into question the validity of the standard scale of geological time.

1. Smiles S.n.d. Self-help, chapter 11. Quoted in: Mackay AL. 1991. A dictionary of scientific quotations. Bristol and Philadelphia: Institute of Physics Publishing, p. 225.

2. These and related factors are discussed more fully in: Roth AA. 1986. Some questions about geochronology. Origins 13:64-85. Section 3 of this article, dealing with geochronological issues, needs to be updated.

3. a) Huggett R. 1990. Catastrophism: systems of earth history. London, New York, and Melbourne: Edward Arnold, p. 232; b) Kroner A. 1985. Evolution of the Archean continental crust. Annual Review of Earth and Planetary Sciences 13:49-74; c) McLennan SM, Taylor SR. 1982. Geochemical constraints on the growth of the continental crust. Journal of Geology 90:347-361; d) McLennan SM, Taylor SR. 1983. Continental freeboard, sedimentation rates and growth of continental crust. Nature 306:169-172; e) Taylor SR, McLennan SM. 1985. The continental crust: its composition and evolution: an examination of the geo-chemical record preserved in sedimentary rocks. Hallam A, editor. geoscience texts. Oxford, London, and Edinburgh: Blackwell Scientific Publications, pp. 234-239; f) Veizer, Jansen S.L. 1979. Basement and sedimentary recycling and continental evolution. Journal of Geology 87:341-370.

4. I.e., Garrels RM, Mackenzie FT. 1971. Evolution of sedimentary rocks. New York: W. W. Norton and Co., p. 260.

5. Judson S. RitterOF. 1964. Rates of regional denudation in the United States, Journal of Geophysical Research 69:3395-3401.

6. a) Dott RH, Jr. Batten RL. 1988. Evolution of the Earth. 4th ed. New York, St. Louis, and San Francisco: McGraw-Hill Book Co., p. 155. Other authors using the same estimates: b) Garrels and Mackenzie, p. 114 (note 4); c) Gilluly J. 1955. Geologic contrasts between continents and ocean basins. In: Poldervaart A, editor. Crust of the earth. Geological Society of America Special Paper 62:7-18; d) Schumm SA. 1963. The disparity between present rates of denudation and orogeny. Shorter contributions to general geology. G.S. Geological Survey Professional Paper 454-H.

7. Sparks B.W. 1986. Geomorphology. 3rd ed. Beaver SH, editor. Geography for advanced study. London and New York: Longman Group, p. 510.

8. a) Ahnert F. 1970. Functional relationships between denudation, relief, and uplift in large mid-latitude drainage basins. American Journal of Science 268:243-263; b) Bloom AL. 1971. The Papuan peneplain problem: a mathematical exercise. Geological Society of America Abstracts With Programs 3(7):507,508; c) Schumm (noteGd).

9. Ruxton BP, McDougall 1.1967. Denudation rates in northeast Papua from potassium-argon dating of lavas. American Journal of Science 265:545-561.

10. Corbel J. 1959. Vitesse de L "erosion. Zeitschrift fur Geomorphologie 3: 1 -28.

11. Menard HW. 1961. Some rates of regional erosion. Journal of Geology 69:154-161.

12. Mills HH. 1976. Estimated erosion rates on Mount Rainier, Washington. Geology 4:401-406.

13. OHierCD, Brown MJF. 1971. Erosion of a young volcano in New Guinea. Zeitschrift fbr Geomorphologie 15:12-28.

14. a) Blatt H, Middleton G, Murray R. 1980. Origin of sedimentary rocks. 2nd ed. Englewood Cliffs, N.J.: Prentice-Hall, p. 36; b) Schumm (note 6d).

15. The surface area of ​​our continents is approximately 148,429,000 square kilometers. With an average height of 623 meters, the volume of their constituent rocks above sea level is approximately 92,471,269 cubic kilometers. If we assume that the average density of rocks is 2.5, then their mass will be 231171x10 12 tons. Dividing this number by 24108x106 tons of sediment carried by the world's rivers into the oceans in one year, it would take about 9.582 million years for the entire continental erosion to occur. That is, in 2.5 billion years at such rates of erosion, the continents could have been eroded 261 times (2.5 billion divided by 9.582 million).

17. The remnant of ancient sedimentary rocks should be very small. All sedimentary rocks (including a significant part of those below sea level) must have been repeatedly eroded. The total mass of sedimentary rocks is 2.4x10 18 tons. Rivers before the development of agriculture carried approximately 1x10"° tons per year, so the erosion cycle must be equal to 2.4x10 18 divided by 10x10 9 tons per year, which is approximately 240 million years, or ten complete cycles of sediment erosion in 2 .5 billion years is a conservative estimate, with some scientists suggesting that there have been "three to ten such cycles since the Late Cambrian" ([a] Blatt, Middleton, and Murray, pp. 35-38; ). the eluvium (remnant) of sedimentary rocks per unit of time is even more significant in some older periods (for example, Silurian and Devonian) compared to fairly close to modern times (from Mississippian to Cretaceous) (see: [b] Raup DM. 1976. Species diversity in the Phanerozoic: an interpretation. Paleobiology 2:289-297. For this reason, some scholars have suggested two cyclical sequences of changes in Phanerozoic erosion rates (eg [c] Gregor ST. 1970. Denudation of the continents. Mature 228:273-2 75). This scheme runs counter to the hypotheses that due to cyclicity, older sediments of a smaller volume were formed. In addition, our sedimentary basins are often smaller in deep areas, limiting the volume of the lowest (earliest) sediments. One might also argue that in the past much more sediment arose from granitic rocks than we have now, and that only a small part of it remains. These precipitations could endure several cycles. Probably the biggest problem this model faces is the chemical mismatch between the sedimentary rocks and the Earth's granitic crust. Granite-type igneous rocks contain, on average, more than half less calcium than sedimentary rocks, three times more sodium, and more than a hundred times less carbon. Data and analysis can be found in: d) Garrels and Mackenzie, pp. 237, 243, 248 (note 4); e) Mason W, Mooge SW. 1982. Principles of geochemistry. 4th ed. New York, Chichester, and Toronto: John Wiley and Sons, pp. 44,152,153; f) Pettijohn FJ. 1975. Sedimentary rocks. 3rd ed. New York, San Francisco, and London: Harper and Row, pp. 21, 22; g) RonovAB, Yaroshevsky A.A. 1969. Chemical composition of the earth's crust. In: Hart PJ, editor. The earth's crust and upper mantle: structure, dynamic processes, and their relation to deep-seated geological phenomena. American Geophysical Union, Geophysical Monograph 13:37-57; h) Othman DB, White WM, Patched J. 1989. The geochemistry of marine sediments, island arc magma genesis, and crust-mantle recycling Earth and Planetary Science Letters 94:1-21 Calculations based on the premise that all sedimentary rocks originate from igneous rocks give incorrect results. based on actual measurements of different types of sediment It is difficult to imagine recyclability between granitic and sedimentary rocks with such a mismatch of basic elements One of the more serious problems is how limestone (calcium carbonate) can be obtained from granite rocks with relatively low content of calcium and carbon Moreover, the redeposition of sedimentary rocks in a localized area on the continent does not seem to solve the problem This is due to rapid erosion, since the figures used for the calculations are based on the amount of precipitation falling from the continents into the oceans and do not include local redeposition. In addition, usually the main sections of the geological column come to the surface and are eroded in the basins of the main world rivers. This erosion proceeds especially rapidly in the mountains, where there are many ancient sedimentary rocks. Why are these ancient sediments still there if they are undergoing redeposition?

18. a) Gilluly J, Waters AC, Woodford AO. 1968. Principles of geology. 3rd ed. San_Francisco: W. H. Freeman and Co., p. 79; b) Judson S. 1968. Erosion of the land, or what's happening to our continents? American Scientist 56:356-374; c) McLennan SM. 1993. Weathering and global denudation, Journal of Geology 101:295-303; (d) Milliman JD , Syvitski JPM 1992. Geomorphic/tectonic control of sediment discharge to the ocean: the importance of small mountainous rivers, Journal of Geology 100:525-544.

19. Frakes L.A. 1979. Climates throughout geological time. Amsterdam, Oxford, and New York: Elsevier Scientific Pub. Co., Figure 9-1, p. 261.

20. Daily B, Twidale CR, Milnes AR. 1974. The age of the lateritized summit surface on Kangaroo Island and adjacent areas of South Australia. Journal of the Geological Society of Australia 21(4):387-392.

21. The problem and some general solutions are given in: Twidale CR. 1976. On the survival of paleoforms. American Journal of Science 276:77-95.

22. Gregor GB. 1968. The rate of denudation in post-Algonkian time. Koninklijke Nederlandse Academic van Wetenschapper 71:22-30.

23. Isett GA. 1981. Volcanic ash beds: recorders of upper Cenozoic silicic pyroclastic volcanism in the western United States. Journal of Geophysical Research 868:10200-10222.

24 See list in: Simkin T, Siebert L, McClelland L, Bridge D, Newhall C, Latter JH. 1981. Volcanoes of the world: a regional directory, gazetteer, and chronology of volcanism during the last 10,000 years. Smithsonian Institution Stroudsburg, Pa.: Hutchinson Ross Pub. Co.

25. Decker R, Decker B, editors. 1982. Volcanoes and the earth's interior: readings from Scientific American. San Francisco: W. H. Freeman and Co., p. 47.

26. a) Ronovand Yaroshevsky (note 17g); b) Ronov say 18 percent volcanic material for the Phanerozoic alone; see: Ronov AB. 1982. The earth's sedimentary shell (quantitative patterns of its structure, compositions, and evolution). The 20th V. I. Vernadskiy Lecture, Mar. 12, 1978. Part 2. International Geology Review 24(12): 1365-1388. Volume estimates Sedimentary rocks according to Ronov and Yaroshevsky are high in relation to some others.Their conclusions are strongly influenced by discrepancies.The total calculated thickness: 2500x10 6 years x 4 cubic kilometers per year = 10000x10 6 cubic kilometers divided by 5.1x10 8 square kilometers = 19.6 kilometers in height.

27 Schumm (note 6d).

28 Mueller St. 1983. Deep structure and recent dynamics in the Alps. In: Nz KJ, editor. mountain building processes. New York: Academic Press, pp. 181-199.

29. Hand S.H. 1982. Figure 20-40. In: Press F, Siever R. 1982. Earth. 3rd ed. San Francisco: W. H. Freeman and Co., p. 484.

30. a) Gansser A. 1983. The morphogenic phase of mountain building. In: Hsb, pp. 221-228 (note 28); b) Molnar P. 1984. Structure and tectonics of the Himalaya: constraints and implications of geophysical data. Annual Review of Earth and Planetary Sciences 12:489-518; c) Iwata S. 1987. Mode and rate of uplift of the central Nepal Himalaya. Zeitschrift for Geomorphologie Supplement Band 63:37-49.

31. Wellman HW. 1979. An uplift map for the South Island of New Zealand, and a model for uplift of the southern Alps. In: Walcott Rl, Cresswell MM, editors. The origin of the southern Alps. Bulletin 18. Wellington: Royal Society of New Zealand, pp. 13-20.

32. Tsuboi C. 1932-1933. Investigation on the formation of the earth's crust found by precise geodetic means. Japanese Journal of Astronomy and Geophysics Transactions 10:93-248.

33. a) Blatt, Middleton, and Murray, p. 30 (note 14a), based on data from: b) Ahnert (note8a).

34 a) Blatt, Middleton, and Murray, p. 30 (note 14a); b) Bloom AL. 1969. The surface of the earth. McAlester AL, editor. Foundations of earth science series. Englewood Cliffs, NJ.: Prentice-Hall, pp. 87-89; c) Schumm (note 6d).

35. A few examples can be found in chapter 12.

  • Chapter 12 4) his behavior, considered as exploratory activity in a situation where the child is on his mother's lap;
  • Diuretics. Anti-pain agents. Uterotropic drugs. Means affecting the contractile activity of the myometrium
  • Case 17. Investment activity in the Russian economy

    • On the planet Earth, indicating ongoing processes inside earth's crust manifests itself daily and in different ways. During our travels, we visited a number of active and extinct volcanoes around the world, and also visited Yellowstone National Park, located in the crater of a supervolcano, where today there are many active geothermal springs and geysers. All these places are united by the fact that the active processes taking place in the earth's crust today or hundreds of millions of years ago have influenced and continue to influence our planet and the climate on it. They are the cause of changes in flora and fauna, as well as a catalyst for evolution. Let's try to briefly understand what volcanic activity causes to our planet, as well as what post-volcanic phenomena occur after eruptions.


    Volcanoes themselves are not as dangerous as we used to think. First of all, we must be wary of the various accompanying phenomena during volcanic eruptions:

    • Volcanic phenomena occur simultaneously with volcanic eruptions.
      • rock avalanches- are formed during vertically directed explosions and contain fragments of previous and freshly erupted lavas.
      • scorching clouds- have a different origin, have high mobility (up to 90 km / h) due to hot gases (up to 900 degrees) emitted by ash particles. They are able to burn in a short time everything that gets in their way.
      • Mud and water streams are formed during the rapid melting of snow caps and glaciers on the slopes of volcanoes during their eruption.
    • Post-volcanic phenomena- arise and occur after volcanic activity subsides, and are associated with the release of volcanic gases, numerous gas-steam jets and hot water with superheated steam.
      • Release of volcanic gases - fumaroles. They are dry high-temperature (more than 500 degrees), sulphurous (hydrogen sulfide) - solfatars (temperature from 100 to 300 degrees) and cold carbon dioxide - mofet (temperature below 100 degrees)
      • Thermae- underground sources of hot water in areas of volcanism. The waters in them are mineralized with various impurities: chloride, carbonate, sulfate, mixed. Often deposits of siliceous or calcareous tuffs occur around such springs. Thermae are common in Kamchatka, Iceland, Baikal, the Caucasus and Italy.
      • Geysers- these are hot springs, consisting of water and steam, which periodically throw water with superheated steam up to a height of hundreds of meters. The most famous valleys of geysers are located in Kamchatka, New Zealand, Iceland, the USA and Japan. Geysers are usually found in fault zones in the earth's crust. The water in them contains impurities of sodium chloride with a mineralization of about 2.5 grams per liter and is characterized by a diverse composition. Hot water, erupting from a geyser under the influence of steam, takes out a large number of dissolved minerals - mainly silicon oxide, which are deposited on the walls of the geyser and around its outlet channel - the vent, forming a tube in the form of a funnel on the surface of the Earth. The resulting deposits form terraces around the geyser in the form of deposits or large cones - geyserite structures.
      • mud volcanoes- cone-shaped hills of different diameters and heights, formed by loose deposits. Due to the accumulation of gases and superheated water vapor coming from below through the cracks in the earth's crust, liquid mud erupts. If the mud is so liquid that it cannot solidify over time, and new eruptions only support the process of mud formation and mixing, then the result is a mud pot.

    Due to its unpredictability, it strongly affects the processes of habitual life on earth. Everyone is well aware of the examples of the outflow of volcanic lava and its destructive properties for all living things around. We also know firsthand what happens to the atmosphere when clouds of ash rise into the air, we immediately recall the eruption of the Eyjafjallajökull volcano in Iceland, which stopped air traffic with many countries for several weeks, resulting in a real transport collapse in Europe.

    • Interesting fact: few people know that the islands were formed on the site of volcanic activity, most of them are of volcanic origin and they are located on the tops of ancient underwater volcanoes.

    Also, in addition to the most famous volcanic phenomenon - volcanic eruption, there are lesser known volcanic and post-volcanic phenomena that occur in our lives. We are talking about mud flows, geothermal springs, thermal baths and geysers. I will tell you more about them.

    Such places usually make the biggest impression on the trip, because they differ in everything from the usual landscapes. They are simply different for perception, and the experience of personal acquaintance with them is valuable. Therefore, we are glad that we visited some of the valleys of geysers personally, and we plan to see others someday! And now we will talk about volcanic activity and post-volcanic phenomena in more detail and illustrate them with photographs from our travels.

    Mud volcano at an altitude of 4300 meters on a high plateau in Bolivia

    Fumarole - the release of volcanic gases to the surface of the earth

    The Bolivian part of the Altiplano is so cold that the water freezes a short distance from the geothermal source

    Mud streams descend from the slopes of active volcanoes and contain a large amount of loose rock fragments that cover these slopes. Most volcanic mudflows are cold, but some are hot.

    A mudflow occurs when a large mass of water somehow gets on the slope of the volcano covered with a layer of debris. This may be the result of a geyser eruption or for some other reason, such as a sudden outburst of water from a crater lake. The largest of these lakes is located in Oregon -. Its volume is about 17.5 cubic kilometers, and in terms of depth it is the first in the United States - 594 meters. If an explosion occurs under such a lake and part of the water splashes onto the slope through a crack in the crater, or rising above the upper edge of the volcanic funnel, this will cause a strong mud flow.

    Facts about mudflows

    • During a study in the US state of Washington, it was found that the deposits around it were left, including prehistoric mud flows, formed as a result of lava splashing due to the rapid increase in the volume of melt water from the slopes of the volcanic funnel, when the lava flows began to move along the slope and came into contact with glacier. Mud flows, formed as a result of the eruption of Mount Rainier, are among the largest of those explored in the whole world and their volume reaches 2 billion cubic meters!
    • Some of the mudflows are formed as a result of avalanches or ash flows mixing with mountain rivers. As a result of steam explosion, the surface layer is destroyed and a mud stream is formed.
    • Mud can also form when ash is released into the atmosphere and comes into contact with rain clouds. As a result, precipitation covers the vegetation in such a thick layer that tree branches break, and weakly fortified soil is subject to shifts.
    • The detrital material, which is applied by mud volcanic flows, hardens like concrete when it cools and dries.
    • Most mud volcanic flows contain a significant proportion of small particles, but they also contain large blocks larger than 35 centimeters, which sometimes reach several meters.

    geothermal springs

    Under the ground, deep and not very deep, underground waters lie. Of the stock is so large that it makes no sense to talk about their volume. As part of the upper layer of the earth's crust, groundwater in solid, liquid and gaseous states perform various important functions and form soil water, aquifers and interstratal horizons. Heated in the earth's crust as a result of modern volcanic activity, movement of the earth's crust or contact with the magma layer, groundwater sometimes comes to the surface. The phenomenon of water rising from the bowels of the earth to the surface with a temperature above 20 degrees is called a “geothermal source”. At the same time, the water temperature must exceed the average annual temperature characteristic of the area, so that the fact of water heating takes place not in the atmosphere, but underground.

    Geothermal waters

    In addition to geothermal sources, consisting of water heated in the earth's crust as a result of volcanic activity, geothermal waters are distinguished separately. Let's see what it is.

    There is a classification of groundwater, according to which water, the temperature of which exceeds 35 degrees, is called geothermal. These waters are located in different places on our planet, which are united by signs of the manifestation of modern volcanism, the latest mountain building, or in large faults in the earth's crust. The following are shared geothermal water types:

    • low thermal(temperature from 35 to 40 °C);
    • Thermal(temperature 40 to 60 °C);
    • High thermal(temperature from 60 to 100 °C);
    • Steam thermal or overheated (temperature above 100 °C).

    High thermal waters in the north of Thailand in the city of Pai. The water temperature here is about 80 degrees.

    For household use geothermal waters are subdivided on the:

    • low potential(from 35 to 70 °C) - for spa water supply, fishing and use in swimming pools;
    • Medium(from 70 to 100 ° C) - for heating the roadbed, airfields and for use in heating buildings and structures;
    • High Potential(from 100 to 300 °C) - for use in a geothermal station to generate electricity.

    Thermae - hot springs

    Thermae, or hot springs, have been used since ancient times to treat various diseases, improve the body and prevent various diseases. It is very pleasant to lie in a warm or moderately hot mineral bath, but the sulfurous smell spoils the impression a little. But what can you not endure for the sake of improving health!

    By the way, the branch of medicine that studies the effect of geothermal waters on the human body is called balneology.

    Coming to the surface water from thermal mineral springs in balneology are divided into:

    • Warm(from 20 to 37 ° C) - heated water, with a long stay in which a person begins to freeze;
    • Thermal(from 37 to 42 ° C) - the most suitable temperature for the human body;
    • Hyperthermal(above 42 ° C) - the human body is not able to withstand such a temperature for a long time.

    Baths in the town of Pai in northern Thailand. The temperature here is from 36 to 40 degrees

    Tourists bask in thermal waters on the Altiplano plateau in Bolivia. Outside it's very cold! And the water is warm!

    Geysers

    Name " geyser" comes from the Icelandic word "geysa", which literally means "gush". A geyser is a column of hot water that shoots from the ground into the atmosphere to a height of tens of centimeters to hundreds of meters under the pressure of steam formed during magmatic overheating of groundwater. Geysers exist in areas with volcanic activity. Valleys of Geysers They form near volcanoes or in areas of volcanic activity where hot magma comes close to the Earth's surface. Groundwater near volcanoes contains impurities of many minerals. As a result of vaporization, part of the water evaporates, and impurities settle, forming a solid bottom of the pool around the geyser.

    Types of geysers:

    • small(fountains of water are thrown out every few minutes, since it does not take very much time to heat up and generate enough steam for the eruption of a geyser);
    • Large(they erupt a column of water much less often, the repetition time depends on the depth of the contact patch of magma and water).

    For example, the Giant Geyser from the Valley of Geysers on the Kamchatka Peninsula in Russia throws out a fountain of water with superheated steam once every 40 minutes, and its height reaches several tens of meters. And (Old Faithful - Old Faithful) in the US state of Wyoming erupts every 65 or 90 minutes (depending on previous eruptions) to a height of 30 to 50 meters, throwing into the atmosphere from 14 to 32 tons of hot water!

    The most famous geyser in the world is Old Faithful in Yellowstone National Park in the USA.

    Facts about geysers

    • The largest known geyser in the world - Waimangu was in New Zealand in 1899-1904 and erupted to a height of more than 400 meters, while throwing out about 800 tons of hot water! But it ceased to exist due to mineral deposits, which not only form the bottom of the geyser basin, but also form a tube on the surface, with walls along the erupting column of water with superheated steam. Thus, the depth of the geyser increases, and the pressure of the water column on the bottom becomes so high that the process of boiling and vaporization slows down and, as a result, the force of superheated steam is no longer enough for an eruption.
    • In Kamchatka, in 1941, the Valley of Geysers was discovered (more than 100 in number, 20 of which are large).
    • There are numerous geysers in the Yellowstone National Park in the USA different types, including the highest modern geyser, called the Steamboat (Steamboat) is located there. The height of its fountain varies from 90 to 120 meters in height.
    • Geysers are regular and irregular. They differ from each other in that the former has a constant cycle of eruptions, while the latter is variable in time.
    • The bulk of the water ejected by the geyser to the surface is of atmospheric origin, sometimes with an admixture of magmatic water.
    • Famous large valleys of geysers are located in Kamchatka in Russia (Valley of Geysers), in the USA (Yellowstone National Park), Iceland (Country of Geysers), New Zealand (northern part of the North Island), Chile (El Tatio High Valley of Geysers at an altitude of 4200-4300 meters in the Atacama Desert on the border with Bolivia), as well as single geysers in Canada, China, and Japan.

    Zones of volcanic activity on Earth

    fire ringCoasts and island arcs Pacific Ocean. Aleutian, Kuril, Japanese, Philippine, Sunda Islands
    Mediterranean-Indonesian zoneCoasts of Italy, Aegean Sea, Eastern Turkey, Iran
    Atlantic zoneIceland, Canary Islands. Ridge in the center of the Atlantic Ocean
    Indian Ocean zoneComoros
    Volcanoes of the central parts of the continentsSouth America - Andes, Africa - Kenya, Cameroon, Ethiopia, Uganda, Tanzania
    Volcanoes on the outskirts of the continentsNorth America, Central America, in the Andes and in the west of South America, Kamchatka, Antarctica

    Volcanoes, individual elevations above channels and cracks in the earth's crust, along which eruption products are brought to the surface from deep magma chambers. Volcanoes usually have the shape of a cone with a summit crater (several to hundreds of meters deep and up to 1.5 km in diameter). During eruptions, sometimes a collapse of a volcanic structure occurs with the formation of a caldera - a large depression with a diameter of up to 16 km and a depth of up to 1000 m. When magma rises, the external pressure weakens, the gases and liquid products associated with it break out to the surface and the volcano erupts. If ancient rocks, and not magma, are brought to the surface, and water vapor, formed during the heating of groundwater, predominates among the gases, then such an eruption is called phreatic.

    Volcanoes that have erupted in historical time or showing other signs of activity (emission of gases and steam, etc.). Some scientists consider active those volcanoes, which are reliably known to have erupted within the last 10 thousand years. For example, the Arenal volcano in Costa Rica should have been classified as active, since during archaeological excavations of the site primitive man volcanic ash has been found in the area, although for the first time in human memory, its eruption occurred in 1968, and before that there were no signs of activity.

    Volcanoes are known not only on Earth. Spacecraft images show huge ancient craters on Mars and many active volcanoes on Jupiter's moon Io.

    Spread of volcanic activity

    Surface distribution of volcanoes the globe best explained by the theory of plate tectonics, according to which the Earth's surface consists of a mosaic of moving lithospheric plates. When they move in the opposite direction, a collision occurs, and one of the plates sinks (moves) under the other in the so-called. subduction zone, which is confined to the epicenters of earthquakes. If the plates move apart, a rift zone forms between them. Manifestations of volcanism are associated with these two situations.

    Volcanoes of the subduction zone are located along the boundary of moving plates. It is known that the oceanic plates that form the bottom of the Pacific Ocean sink under the continents and island arcs. Subduction regions are marked in the topography of the ocean floor by deep-sea trenches parallel to the coast. It is believed that in the zones of plate subsidence at depths of 100-150 km magma is formed, when it rises to the surface, volcanic eruptions occur. Since the angle of subsidence of the plate is often close to 45°, the volcanoes are located between the land and the deep-sea trough at a distance of about 100-150 km from the axis of the latter and form a volcanic arc in plan, repeating the outlines of the trough and the coastline. Sometimes people talk about the "ring of fire" of volcanoes around the Pacific Ocean. However, this ring is discontinuous (as, for example, in the region of central and southern California); subduction does not occur everywhere.

    Rift zone volcanoes exist in the axial part of the Mid-Atlantic Ridge and along the East African fault system.

    There are volcanoes associated with "hot spots" located inside the plates in places where mantle jets (hot magma rich in gases) rise to the surface, for example, the volcanoes of the Hawaiian Islands. It is believed that the chain of these islands, stretched in a western direction, was formed in the process of drifting to the west of the Pacific plate while moving over the "hot spot".

    Now this "hot spot" is located under the active volcanoes of Hawaii. To the west of this island, the age of the volcanoes gradually increases.

    Plate tectonics determines not only the location of volcanoes, but also the type of volcanic activity. The Hawaiian type of eruptions prevails in areas of "hot spots" (Furnaise volcano on Reunion Island) and in rift zones. Plinian, Peleian, and Vulcanian types are characteristic of subduction zones. Exceptions are also known, for example, the Strombolian type is observed in various geodynamic conditions.

    Volcanic activity: frequency and spatial patterns.

    Approximately 60 volcanoes erupt every year, and about a third of them erupted in the previous year. There is information about 627 volcanoes that erupted over the past 10 thousand years, and about 530 - in historical time, with 80% of them confined to subduction zones. The greatest volcanic activity is observed in the Kamchatka and Central American regions, the zones of the Cascade Range, the South Sandwich Islands and southern Chile are calmer.

    Volcanoes and climate . It is believed that after volcanic eruptions, the average temperature of the Earth's atmosphere decreases by several degrees due to the release of the smallest particles (less than 0.001 mm) in the form of aerosols and volcanic dust (at the same time, sulfate aerosols and fine dust enter the stratosphere during eruptions) and remains so for 1 -2 years. In all likelihood, such a decrease in temperature was observed after the eruption of Mount Agung on the island of Bali (Indonesia) in 1962.