Дата публикации: 03 сентября 2021
Автор(ы): Gennady KARPOV →
Публикатор: Научная библиотека Порталус
Рубрика: ТУРИЗМ И ПУТЕШЕСТВИЯ →
Источник: (c) Science in Russia, №6, 2010, C.22-31 →
Номер публикации: №1630674151
Gennady KARPOV, (c)
by Gennady KARPOV, Dr. Sc. (Geol. & Mineral.), Deputy Director of the Institute of Volcanology and Seismology, the Far Eastern Branch of the Russian Academy of Sciences (Petropavlovsk-Kamchatsky)
Kamchatka, together with the Kuril Islands to the south, is a unique volcanic region both in Russia and elsewhere in the world. Most of the planet's active volcanoes are out there. "The Kamchatka-Kuril chain is one of the most wonderful phenomena in the globe's structure. It holds a key to understanding the origin of the Pacific Ocean and the orogenic processes in general," said in the 1930s a noted Russian geologist and petrographer, member of the USSR Academy of Sciences Alexander Zavaritsky.
VOLCANISM, A GLOBAL PHENOMENON
Volcanic eruptions have taken place on the Earth in all geological epochs, and the scale of volcanic activity far back in the past was more grandiose than now. Space research shows that volcanic processes on other planets of the solar system are also of great importance in the formation of their material composition and relief. In their turn, geologists say that many mineral deposits are closely associated with old volcanoes and their rocks. That is why contemporary active volcanoes provide answers to many questions of interest to mankind.
Volcanology as a science is based on a foundation of geology. Besides, data on eruption processes and related products were a starting point of the first geological constructions. The better research methods of the deep-seated regions of the Earth, the more features of an independent science volcanology has been acquiring with the extensive use of new advances in physics, mathematics and physical chemistry. Conversely, in keeping with the feedback law, new evidence on active volcanoes spurs discoveries in physics, chemistry, mineralogy and lately, in biology, and extends our knowledge of the Earth, its history and evolution.
As a matter of fact, today the scale of volcanism is significant indeed. So, only on Kamchatka approximately 60 • 106 tons of magmatic substance is ejected to the surface every year. By estimates of Valery Yermakov, Cand. Sc. (Geol. & Mineral.), only two volcanoes of the Klyuchevskoy group, Bezymyanny and Klyuchev-skoy, have "spewed forth" around 200 km3 of geological material in the last 10 years. According to Vladimir Vlodavts (1883-1992), Dr. Sc. (Geol. & Mineral.), an eminent scientist, organizer and the first director of the Kamchatka Volcanological Station of the USSR Academy of Sciences (from 1935), the author of the Handbook on Volcanology, as many as 1,500 eruptions of 320 volcanoes took place worldwide all through the 20th century.
Volcanoes awake especially often in the zone of the Pacific Ring of Fire, which enframes the Great Ocean, namely, on Kamchatka, the Kurils, in Japan, on the Philippines and Hawaii. Widely known also are eruptions in the Mediterranean region, in East and Central Africa and that of a rather active volcano in Iceland lately. While in Russia human settlements are situated, as a rule, far from volcanoes, in other countries people have been settling close to them all the time, often due to the shortage of land and mainly because of fertile ground covered with volcanic ashes.
Therefore, the major objective of volcanology today is identification of evidence making it possible to forecast eruptions, earthquakes and tsunami waves as well as to study the mechanism of such processes. As Sophia Naboko (1909-2005), a researcher of our institute, has put it, volcanic vents are small windows through which one can peer into the earth's interior. That is why specialists seek to approach a crater as close as possible so as to take lava temperature and study the chemical composition of the outcoming liquid, solid and gaseous material. It is also important to determine the energy of an eruption, mass of substances and its duration, stages, and so on.
VOLCANOES OF KAMCHATKA
Twenty nine active volcanoes out of the world's 817 are located on Kamchatka and 37, southward on the Kurils.* Besides, there are several hundred volcanoes out there, ones that, though inactive, keep their form quite well and, therefore, are of interest to specialists.
* See: V. Znamensky, "One of a Kind", Science in Russia, No. 4, 2000; "Energy of Volcanoes", Science in Russia, No. 1, 2006,–Ed.
The volcanoes of Kamchatka are generous where great eruptions are concerned. So, in March 1956, the best-known eruption of the Bezymyanny volcano took place. A giant explosion cut off the 300 m head of the volcano, and its ashes were found as far as London. In 1961, the Plosky Tolbachik and Mutnovsky volcanoes became active again. In November 1964, the great Shiveluch volcano awoke in the north of the peninsula. Its eruption lasted about one hour, but it exceeded all previous ones in its energy (2 • 10'4 J) and ejected material (1.5 km3). The fallout speed made up 31 m/s and the pressure, 1,000 atm. Volcanic blocks of many tons were thrown away to 10-12 km. Besides, after a 16-year interval, in 1980 this volcano awoke again. Within the intracrateral caldera* a lava dome started to grow. It continues to grow even now and is accompanied by recurrent explosions. According to Nikolai Zharinov, Cand. Sc. (Geol. & Mineral.), a member of the Kamchatka (Klyuchevskaya) Volcanological Station, the intrusion of viscous lava causes deformation of the lava dome slope. A squeezing-out of separate blocks causes vertical and horizontal displacements of the volcano's slopes by dozens and sometimes hundreds of meters at a speed ranging from several decimeters to several meters per day.
In 1966 an eruption took place from a subordinate vent (at a height of 3,200 m) of the highest volcano of Eurasia, Klyuchevskaya Sopka (about 5,000 m high). In the autumn of 1974 it awoke again and for a long time ejected lava up to 1,100°C hot. Lately it has been char-acterized by practically permanent explosive and effusive (lava) activity. The Karymsky volcano is also active again. Throughout the 20th century it erupted as often as 21 times! In January of 1996 it came up with five powerful ashfalls and lava flows, when an avalanche of volcanic stones of the spherical, pear-shaped and tubular form 10 cm to 1.5 m large (occasionally even larger than that) was thrown out. The eruption of this volcano is still on.
It should be noted that volcanoes can show their violent temper for many millennia, calming down now and then (sometimes for hundreds of years) and waking up again. In the long run, eruptions cease. But pockets of high-temperature magma persist in the earth's interior still for thousands of years. They warm the overlying rocks that become reservoirs of heat. Surface waters getting in through cracks, are heated and enriched with magmatic gases and depth components, and then outcrop in the vicinity of the original source, in depression areas, as a rule.
These thermal springs and sometimes also geysers (remarkable for periodic ejections of water steam) are of great scientific and practical significance. Their reserves in volcanic regions are virtually inexhaustible. For example, Kamchatka has unique storages of hot water both in area and in volume. Owing to the work of our geologists and volcanologists around 150 groups of hot springs were detected there. The temperature of 22 springs is 75-100°С at the ground level, and that of another 16 springs it is ≥ 100°C even at moderate depths.
Young (present-day) geothermal systems joined in large natural groups have the highest thermal power.
* Caldera (from the Spanish caldera, a kettle or bowl) is a cirque depression with steep walls and more or less flat ground; it is formed due to a collapse of the volcano head and, in some cases, of the adjacent locality. The caldera differs from the crater in its origin and large size, it is up to 10-15 km and more across.–Ed.
They include the widely known Pauzhetsky, Mutnovsky and Semyachinsky geothermal regions.
Studies of these systems by exploration drilling (there are drill wells as deep as 1,500 m today) have added to our knowledge about their true nature. Research undertaken by Russian hydrogeologists specializing in geo-thermics–Valéry Averyev, Viktor Sugrobov, Yevgeny Vakin, Vladimir Kononov, Boris Polyakov and others-shows that such objects represent specific hydrodynam-ic structures occurring in the upper parts of the earth's crust at intense heat input from abyssal horizons in the form of magmatic vapor or melting. Their thermal power is 25-75 thous. cal/s*, and the specific density of flow is 50-100 times higher than that in the Mediterranean.
By expert estimates the total thermal power of the Kamchatka high-temperature thermal springs makes up 3.8 • 10s cal/s and those with the temperature of less than 100°C–7.7 • 107 cal/s. Consequently, high-temperature resources alone are sufficient for building geothermal power plants of the aggregate capacity of about 300,000 KW. By comparison, it is equivalent of burning 1 mln tons of coal per year. Besides, the comprehensive utilization of thermal waters discharged from turbines of electric power plants, say, for the heating of industrial and residential buildings, hospitals, kindergartens, swimming pools, greenhouses, and the like exceeds manifold the efficiency of geothermal power plants. In addition, minimal contamination of the environment is a great advantage of using geothermal water and steam in the national economy.
About 30 electric power plants are operating on underground heat worldwide (in Italy, New Zealand, USA, Japan, Iceland, Mexico). The capacity of the biggest of them in California is about 400,000 KW. In Russia (on Kamchatka) the Pauzhetskaya and Mut-novskaya** geothermal power plants are in service.
* Heating rate is measured by thermal power per unit of time.–Ed.
** The Pauzhetskaya geothermal power plant is near Pauzhetka village and the Koshelev and Kambalny volcanoes. The oldest geothermal power plant, it was put into operation in 1966. It supplies electric power to Ozernaya and Zaporozhye townships and local fish-processing factories. Its capacity is 14.5 MW (in 2004), and the annual electrical power output is 59.5 mln KWh. It is being upgraded so as to bring the rated power to 17 MW. The Mutnovskaya geothermal power plant is using natural heat of the Earth for electric power production. It is situated northeast of the Mutnovsky volcano in the southeastern part of the Kamchatka Peninsula 780 m above sea level and 116 km from the city of Petropavlovsk-Kamchatsky. Its first phase was commissioned in April 2003 with the installed capacity (in 2007) of 50 MW and the rated power of 80 MW. It is fully automated. The Verkhne-Mutnovskaya geothermal power plant with the installed capacity (in 2004) of 12 MW was put into operation on the same Mutnovsky thermal water deposit on December 29, 1999. Geothermal plants account for 30 percent of power supply of the Kamchatka central power system.–Ed.
Hot springs offer great opportunities for the greenhouse economy. Suffice it to say that residents of a northern island like Iceland, rich in such springs, make a rational use of them and provide themselves fully with vegetables and fruits. Our research institute has also built several greenhouse centers operating on underground hot waters.
The great curative value of natural hot waters is also well known. But while numerous baths and spas set up on the basis of the Caucasian mineral waters gained general acceptance fast, Kamchatka hot springs have still a long way to go. There are table drinking mineral waters out there, for example, Malkinskaya acidulous chalybeate chloride-hydrocarbonate sodium-calcium water similar to the Yessentuki No. 4 brand in its chemical composition and good for gastrointestinal diseases. As far back as 1818 a Russian military surgeon, Ivan Lyubarsky, set up hot spring baths in the Malki village (130 km south of Petropavlovsk-Kamchatsky) and treated rheumatic patients with much success.
Known from long ago are the Drankinsky thermal springs in the middle reaches of the right tributary of the Dranki river, the Gilmimilvayama (6 km of its estuary) and also the Nalachevsky and Kraevedchesky waters located not far from Petropavlovsk-Kamchatsky. The favorable combination of temperature, chemical composition and microelements, with arsenic and boron taking a special place, put these regions on a par with the world-famous spas, such as La Bourboule (France) and Durkheim (Germany).
Today two specialized spas, at Ketkino and Paratunka, are in service on Kamchatka. Hot mineral waters and sulfurated peloid (mud) are an important part of treatment procedures. Health baths have also been built at Esso and Anavgay hot springs. Baths and outdoor pools are in service on the Ozernovsky, Bolshe-Banny and Kireunsky thermal springs.
LABORATORY OF MINERALS
Hot springs provide extremely important information on conditions of mineral deposits formation. So, ore mineral deposits similar to those formed by ores of mined deposits are found when drilling for some modern hydrothermal systems at moderate depths and sometimes also directly in the subsurface zone. To study their formative conditions means to understand where exactly and more rationally they should be prospected for (without extra efforts and time consumption).
The Valley of Geysers* and caldera of the Uzon volcano** are an example of similar natural laboratories of minerals. They are situated 180 km north of Petropavlovsk-Kamchatsky in the so-called East Volcanic Zone of the peninsula characterized by modern volcanic activity.
There is every indication of recent magmatic activity. Several constructions of extinct volcanoes are well preserved, such as the Zhupanovsky, Taunshitsa, Unany, Krasheninnikov and Kronotsky volcanoes. The Karym-sky and Maly Semyachik volcanoes erupt from time to time. Numerous massifs are at the stage of hydrothermal activity when molten rock already cannot erupt to the surface, while underground heat is quite sufficient
* See: "Tragedy in the Valley of Geysers", Science in Russia, No. 6, 2007.–Ed.
** See: Ye. Bonch-Osmolovskaya, "Thermophils: the Planet's Past, Biotechnology's Future", Science in Russia, No. 4, 2010.–Ed.
to warm and lift water to a zone of such heating. Therefore, it comes up in the form of numerous steam-gas jets, hot springs, and sometimes geysers. Hot springs and geysers occur in lowlands in the vicinity of volcanoes. High-temperature steam-gas jets, or fuma-roles*, are found on volcanic mountains proper. Condensed on the ground surface, they form low-yield hot streams saturated with acids and acting vigorously on rocks. For many thousands of years of hydrothermal activity, the rocks, which build up the upper shield of volcanoes, change completely. They turn into a whitened clayey or dense siliceous mass whose spatial position obeys certain regularities.
Sometimes only a low-level circular framing is left instead of a volcanic massif as a result of rather intense, ignimbrite-forming eruptions**. It is formed by the oldest rocks, and fresh volcanic rocks are usually scattered around by powerful explosion and deposited in the neighborhood. Similar eruptions cause a prompt depletion of deep-seated magmatic chambers and sinking. Volcano top rocks descend through huge circular fractures and kind of "suppress" the volcanic chamber. As a result, a large structure in the form of a circle, the so-called caldera appears.
The caldera of the Uzon volcano was presumably formed just this way and, together with the adjacent Valley of Geysers, is considered a gem of Kamchatka.
All local tourist routes converge here. New minerals and shows of oil, the world's youngest, are discovered in this district. Therefore, many experts–geologists, microbiologists, ecologists are working out there.
RUSSIAN VOLCANOLOGY TODAY
Sergei Fedotov, a leading Russian volcanologist (elected to the national Academy of Sciences in 1992), who headed our research institute for more than 30 years, had this to say: "There are several volcanological research institutions in the world–in Russia, USA, Italy, Japan, New Zealand and in other countries. The Institute of Volcanology in Petropavlovsk-Kamchatsky is the largest."
This research institute was established in 1962, with corresponding member of the USSR Academy of Sciences Boris Piyp its first director. After his death in 1966 the institute came to be headed by corresponding member of the USSR Academy of Sciences Georgi Gorshkov (1966-1970), Konstantin Zelenov (1970), Dr. Sc. (Geol. & Mineral.), and Acad. Sergei Fedotov (1971-2003). In 2004 this research center was reorganized into the Institute of Volcanology and Seismology of the Far Eastern Branch of the RAS. It centers on vol-canism and related geological, geophysical, geochemi-cal and geothermal processes; it is also involved with the mechanism of volcanic activity, volcanic ore formation and geoecology. Seismic activity, tectonics, geody-namics, the structure and evolution of volcanic zones; prediction of earthquakes and volcanic eruptions as well as seismic, volcanic and tsunami hazards are among its priorities.
* Fumarole (from the Italian fumarola, fumo–smoke) is a source of hot gases in craters and on slopes of volcanoes, and also in the crust of cooling lava flows. Gases dissolved in magma come out through fumaroles.–Ed.
** Ignimbrites [Lat. ignis, fire + imber, shower]-rocks formed by showers of tiny heated fragments of volcanic lava erupted to high altitudes.–Ed.
Our institute is true to traditions of the foremost vol-canologists Academicians Alexander Zavaritsky and Franz Levinson-Lessing. On their initiative a volcanic station was set up in 1935 at Klyuchi, in the area of the world's largest concentration of volcanoes, the Klyuchevskaya group.
The names of other scientists of the younger generations, who have contributed to research in volcanology, are likewise well known to the world scientific community. They are Kamchatka volcanologists Alexander and Igor Menyailov; Sophia Naboko, Dr. Sc. (Geol. & Mineral.), formerly the head of the Postvolcanic Processes Laboratory; Alexander Svyatlovsky, Dr. Sc. (Geol. & Mineral.); Yevgeny Markhinin, a traveler, writer and scientist, and the author of the volcanic theory of the Earth's outer shells; Pavel Tokarev, Cand. Sc. (Phys. & Math.), a geophysicist heading a research team involved with prediction of volcanic eruptions and implicated mechanisms; Igor Gushchenko, Cand. Sc. (Geol. & Mineral.), a member of many scientific expeditions; Henrietta Bogoyavlenskaya, Cand. Sc. (Geol. & Mineral.), a leading researcher of our Scientific Museum; Ivan Kirsanov, a geologist and petrographer, head of the Klyuchevskaya Volcanic Station, one of the leading volcanologists, and an active organizer of field studies; Boris Ivanov, Cand. Sc. (Geol. & Mineral.), a scientist of world reputation, former head of the Klyuchevskaya Volcanic Station; Gennady Avdeyko, Dr. Sc. (Geol. and Mineral.), chief researcher and winner of the USSR Council of Ministers Award; Ivan Melekestsev, Dr. Sc. (Geol. and Mineral.), heading the Laboratory of Dynamic Volcanology, Kamchatka State University professor and Honored Scientist of the Russian Federation.
At present we employ a staff of 272, including 118 research scientists. Our analytical center is carrying out hydrochemical, silicate, X-ray fluorescent, gas chromatographic and microprobe analyses. The institute comprises 14 research laboratories, the Kamchatka Volcanological Station at Klyuchi, a network of stations, with Pauzhetsky and Paratunsky being the biggest, and also Karymskaya, Uzonskaya and Mutnovskaya field bases.
Our international cooperation is wide enough. Universities of USA, Italy, Japan, Germany, France, Great Britain and Mexico are our regular partners in joint research both in Russia and in other countries. We hold field studies, conferences, meetings and also carry out exchanges of scientific literature. Our institute publishes the Volcanology and Seismology journal (in Russian and English).
People have always wished to know how various rocks, precious stones, gold, silver and metal ores were formed. They have conducted numerous experiments and natural observations. But volcanoes seem to be most informative for the cognition of regularities implicated in the formation of rocks and minerals. They, the volcanoes, have received much notice not only because of mighty eruption and spontaneous violence of fire but also because of creative processes.
Brave explorers, who dared to look into an eruptive crater, discovered a mysterious and colorful world, and witnessed a new substance being born. From what depths do particular materials rise to the surface? What are their motive forces? Why does an eruption occur just in this particular place? These and other intriguing questions have always been on the mind of volcano-logists.
Identification of the magma origin is thus one of the main problems. As a matter of fact, volcanism is the movement of magma in the crust mantle and on the surface of the Earth. Magma is a silicate melt with gases dissolved in it and can be single-phase, that is in a liquid aggregative state. But it also can be bi - and polypha-sic with liquid, gas and solid crystals in. Types of eruptions are distinguished depending on the ratio and properties of these components, which affect, first of all, viscosity.
The phenomenon of volcanism is still a terra incognita in many respects, and so are the bowels of the earth for that matter. For example, it is not clear yet at what depth magma originates. We can assume that the melting of substance and magma formation should take place where the temperature of a material forming, most likely, the upper mantle reaches the melting point under proper pressure. Proceeding from the depth zone of volcanic earthquakes and the probable effect of almost complete nonpassage of transversal seismic waves (observed at a depth of 50-60 km), the top of the magma formative zone under Kamchatka volcanoes
should be located at a depth of around 60-80 km. But do magmatic focal points represent compact bodies or is magma dispersed in fissure zones? Both scenarios are possible. It cannot be ruled out either that the delivery of a magmatic substance to the ground surface proceeds by fits and starts directly from more remote zones of the Earth mantle. Volcanologists have found that the composition of the magmatic material changes in time even within one and the same volcano. Probably this is a consequence of the evolution of volcano inflow intensity.
It should be noted that the present-day activity of volcanoes of the Kurils-Kamchatka island arc and the ecological environment are a priority subject of our research coupled to cumulative volcanism of different types, characteristics of the eruptive (explosive) evolution of extrusive (squeezing out) domes of andesitic volcanoes, the geochemistry of solid, liquid and gaseous products of eruptions, the occurrence of dangerous processes accompanied by volcanic phenomena, their interaction with the environment and effect on the climate. Academician Yevgeny Gordeev, the present director of our research institute, is in charge of the fundamental elaboration of this research area.
It is common knowledge that Kamchatka is a land of earthquakes. According to expert data, the natural seismic hazard in this region is 100 times as high as in the Caucasus and Central Asia; this is the most active seismic zone in Russia. Therefore, long-term seismic and volcanic prognosis* for the Kurils-Kamchatka arc is all important. A group of scientists headed by Academician Sergei Fedotov is concerned with this subject. Good progress has been made in practical terms. For example, the forecast of the Ust-Kamchatka earthquake of December 15, 1971, proved true. Besides, the site of the next violent earthquake was likewise identified correctly. It took place on June 17, 1973, east of the Maly Kurils mountain range. Pavel Tokarev, Dr. Sc. (Phys. & Math.), a researcher of our institute, made an accurate calculation of the time and place of the unique Big Fissure Tolbachinsky Eruption of 1975-1976 a week before.
Acad. Sergei Fedotov in his review article on the 30th anniversary of the Council of the Institute of Volcano-logy and Seismology of the Far Eastern Division of the RAS and the Kamchatka Branch of the Geophysical Service of the RAS and dealing with prediction of earthquakes and volcano eruptions said this in part: "Observation networks were created in Kamchatka, dif-
* See: O. Kondratyev, "New Paradigm of Earthquake Prognostication", Science in Russia, No. 4, 2000; V. Morgunov, "Earthquake Forecasts for Tomorrow", Science in Russia, No. 1, 2004.–Ed.
ferent techniques developed, researchers trained, and adequate conditions prepared for large-scale work in search of early indications of earthquakes and volcano eruptions and their prediction." He is certainly right. Indeed, prediction of earthquakes and volcano eruptions is among the most difficult problems of the earth sciences. And yet, positive results are already on hand, and researchers of our institute have made a major contribution toward this end.
Furthermore, after the eruption of lava and ash dies out, the poisonous "breathing" of a volcano does not stop for a long time because of active fumaroles in its crater, with water or, rather, water steam being their main component. But the admixture of potent acids, such as sulphuric, chlorohydric and hydrofluoric acids, and also such gases as hydrogen sulphide, sulphur dioxide, carbon sulphide, disulphide and carbon monoxide, makes them rather aggressive. Condensing, the vapor and gas mixture gives rise to hydrothermal solutions, which have very high acidity in the zone of their formation. They erode, and do it fast, rocks of any hardness, dissolving them and taking out the readily soluble components Na, K, Ca, Mg, which, in their turn, enter into chemical reactions with wall rocks and form new minerals. As a result of such interactions, new modified changed rocks appear. Depending on the physicochemical conditions (temperature, pressure, solution acidity, original composition of rocks, etc.), they may occur as useful minerals. For instance, some types of clay and ocher* come into being this way.
For example, in a crater zone of one lava cone of the Big Fissure Tolbachinsky Eruption of 1975-1976 our researcher Lidiya Vergasova discovered around 30 new minerals, among them arsenates (salts H3AsO4 resembling phosphates in chemical characteristics), vanadates (raw material for the production of vanadium), selenites, sulphates and oxysulphates of copper and zinc.
Volcano craters are also wonderful natural laboratories in the open air. Stepping on the hot ground of hydrothermal systems in areas of active volcanism and watching the violent columns of vapor spurting from hot springs and geysers, the bubbling mud potholes and numerous multicolored water streams of different temperature, you come to realize: what giant energy is concealed in the underground storerooms of the Earth!
* Natural pigment consisting of iron oxide with clay admixture. The color of ocher varies from lemon to golden yellow and buff.–Ed.
Опубликовано на Порталусе 03 сентября 2021 года
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