THE UNKNOWN TUNGUSKA:
What we know and what we do not know about the great explosion of 1908
* * *
The summer of 2012 coincides with the 104th anniversary of the enigmatic event known as the fall of the Tunguska meteorite (in reality - a space body of unknown origin, almost definitely not a meteorite at all). In the past decades, some (the most obvious) features of this event were widely publicized in the popular and scientific press. But neither the general public, nor the world scientific community has in fact paid serious attention to the real - very complicated - picture of this event. The language barrier is also difficult to surmount (the key publications on the subject matter are in Russian) and consequently the Tunguska problem is usually thought of either as solved long ago by specialists in meteoritics, or as a complete blank space in science. Neither of these approaches is close to the truth. We do know now something very essential about the Tunguska phenomenon. First of all, we know with certainty, to which great extent it is anomalous. Let's look at this startling picture...
* * *
1. A surprise from the blue
Beginning on June 27, 1908, strange atmospheric optical anomalies were observed in many places of Western Europe, the European part of Russia and Western Siberia. They included unprecedentedly active formation of mesospheric (silvery) clouds, bright "volcanic" twilights, extremely intense and long solar halos, etc. These anomalies were gradually increasing in intensity during three days, when in the sunny morning of June 30, 1908, a luminous space body of unknown origin flew over Central Siberia, moving generally to a north-westerly direction. The body was seen in many settlements of the region, its flight being accompanied by thunder-like sounds. Although this region is only sparsely-populated and, besides, systematic gathering of the eyewitnesses' testimonies started rather late (in the 1920s), we have got by now some 500 written accounts which contain more or less detailed descriptions of the flying body. Its shape was mostly described as roundish, spherical, or cylindrical; its color as red, yellow, or white. There was no smoky trail, so typical for large iron meteorites, but many witnesses saw behind the body vivid iridescent bands looking like a rainbow.
When flying at 7 h 14 m of local time (that is, at 0 h 14 m GMT) over the area with the coordinates 60° 53' N, 101° 54' E, not far from the Podkamennaya Tunguska river, the body exploded, the TNT equivalent of the effect being 30 to 50 megatons. The explosion was accompanied by a bright flash and a powerful blast. I would like to cite here an account of Semyon Semenov who lived then in the little trading station Vanavara, some 70 km to the south-east from the epicenter of the explosion. (The latter was located at a lonely marshy region, named the Southern Swamp.) In 1927 Semenov recalled: "I sat on the steps of my house, facing the north. ...Suddenly the sky in the north split apart and there appeared... a fire that spread over the whole northern part of the firmament. At this moment I felt intense heat, as if my shirt took fire. I wished to tear up my shirt and throw it off, but at this moment the sky shut and a powerful strike threw me down from the steps... At this moment I fainted, but my wife ran out of the house and helped me to get up... After the stroke there started a very loud knocking - as if stones were falling from the sky..."
The sound of the explosion was heard as far as 1200 kilometers from the epicenter, and within 200 kilometers there were broken windows which faced northwards. Its seismic wave was recorded in Irkutsk, Tashkent, Tbilisi and Jena. The shock wave of the Tunguska explosion leveled more than 2100 square kilometers of the forest; over an area of some 200 square kilometers vegetation was burnt by the flash. After that there started a major forest fire.
Some six minutes after the explosion there began a local magnetic storm, closely similar to geomagnetic disturbances following nuclear explosions in the atmosphere. It was detected by the Magnetographic and Meteorological Observatory in Irkutsk. The storm lasted for four hours.
By the early morning of July 1, strange light effects in the skies that started three days before the event jumped to their peak. Later, after July 1, these effects swiftly reduced; still some aftereffects took place up to late July of 1908.
2. Labyrinths of hypotheses
Even from this short and simplified description of the Tunguska phenomenon, one can see its real extent. The more interesting seems the lack of any serious reaction to it in science of those days. Although some scientific journals discussed the strange atmospheric anomalies, no attention was in fact paid to the extraordinary event that had taken place in Siberia. Yet some local Siberian newspapers did publish eyewitnesses' accounts, and the journalists supposed that a huge meteorite had fallen in taiga.
In this connection, we should give his due to Director of Irkutsk Magnetographic and Meteorological Observatory Dr. Arkady Voznesensky who realized immediately after the event that the curious earthquake recorded by the instruments of the Observatory had something to do with the fiery body described in the newspaper reports. After processing the seismograms, Arkady Voznesensky established approximate coordinates of the space body fall: 60° 16' N, 103° 06' E, as well as its moment: 7 h 17 m 11 s of local time. Taking into account imperfection of the instruments he used, accuracy of these results is worthy of admiration. Unfortunately, they have not been published until 1925. For more than a decade the Tunguska "meteorite" was in fact forgotten.
When I define my description of the Tunguska fall as "simplified," it is not just a form of speech. In reality, even now, 104 years after the event, many important details of the phenomenon remain obscure. We do not know for sure, how many bodies participated in it, nor how many explosions happened. It is even not clear whether we can use here the word "explosion" in its proper sense, or it would be better to carefully use the expression "an explosion-like energy release." The real level of intricacy and anomalousness of the Tunguska phenomenon was perceived only after many decades of active investigations in this region.
At first, however, the situation seemed more or less clear. In 1921 information of the Tunguska fall came to light anew, when an expedition of the Russian Academy of Sciences, aimed at gathering data about various meteorites and led by Leonid Kulik, visited Central Siberia. There was no question that it had been a huge meteorite, either stone, or iron, and therefore several well-equipped special expeditions were subsequently sent to the site. Kulik continued to actively explore the area up to World War II. In these expeditions he obtained much valuable data on the event.
Even when (immediately after discovering the area of the leveled forest) it was established that at the epicenter of the explosion the trees were still standing upright, showing no sign of a meteorite crater, no real significance was attached to this fact. There was just a little shift from the idea of a single meteorite body to that of a meteorite shower (which had to arise from destruction of the initial body due to air resistance at some altitude above the Earth's surface). Respectively, the forest was supposed to be leveled by the ballistic shock wave of the collapsed body. Leonid Kulik mistook usual thermokarst holes for meteorite ones, and nobody should throw a stone at him for this mistake: being a really eminent specialist in meteoritics, he looked for a meteorite, not for something else.
Nevertheless, as time passed, some scientists began to feel, rather intuitively, that the meteorite hypothesis had serious weak points. In spite of intensive search for remnants of the meteorite, there was not found even a milligram of its substance. In the early thirties Francis Whipple supposed that the Tunguska space body (TSB) had in fact been the core of a small comet, Vladimir Vernadsky put forward a hypothesis about a cloud of cosmic dust, and Igor Astapovich assumed that the TSB had ricocheted off the lower layer of the atmosphere...
But it was the Soviet engineer and science-fiction writer Alexander Kazantsev who understood in 1945 the real importance of the "first Tunguska anomaly" - the overground character of the explosion. He advanced the hypothesis of an extraterrestrial spaceship that had met with disaster due to a malfunction at the final stage of its space voyage. The author of this hypothesis subsequently recalled that he had been much impressed by a description of the nuclear explosion over Hiroshima and its similarity to the Tunguska explosion.
In certain respects the latter does resemble nuclear ones, but it was ascertained only 20 years later, and so one cannot but admire the deep insight of Kazantsev's.
Specialists in meteoritics at once raised objections to such a fantastic idea. Thus, a team of the most distinguished Soviet astronomers wrote in 1951 in the popular-science journal "Science and Life": "There is no question that immediately after the meteorite fall a crater-like depression formed where now the Southern Swamp exists. It was relatively small and soon became inundated with water. In subsequent years it was covered by silt and moss, filled with peat hummocks and partly overgrown with bushes. The dead trees standing upright can be seen not at the center of the catastrophe, but on the hillsides which surround the hollow..."
However the work of the first post-war Tunguska expedition, organized in 1958 by the Committee on Meteorites of the USSR Academy of Sciences (KMET) made everyone involved in the discussion to agree: the Tunguska space body had in fact exploded in the air and therefore hardly could have been a usual meteorite.
Thereafter the number of anomalies discovered on the site of the Tunguska explosion began to grow steadily. The hypothesis of a thermal explosion, according to which the Tunguska space body was a meteorite or the core of a small comet that exploded as a result of the rapid deceleration in the lower atmosphere, met with difficulties, attempting to assimilate all of them. And as soon as 1962 the Committee on Meteorites got rid of the affair, turning it over to the Commission on Meteorites and Cosmic Dust of the Siberian Branch of the USSR Academy of Sciences. The problem of the Tunguska phenomenon was, so to speak, exiled to the place of its birth.
In reality it was the Independent Tunguska Exploration Group (ITEG) that became the center of the Tunguska studies. It was not the only research body in this field, but its role can hardly be overestimated.
The Independent Tunguska Exploration Group is a kind of informal scientific research institute aimed at thorough studies of the Tunguska problem. It was formed in 1958 in the Siberian city of Tomsk and consisted at first of a dozen of specialists in various scientific disciplines, mainly physicists and mathematicians. A few years later the "core" of this informal institute involved about 50 scientists, while a hundred specialists took part in fieldwork each year, with an amazing 1,000 researchers from various scientific institutions all over the Soviet Union collecting and analyzing relevant materials.
Although traces of the Tunguska explosion begin to disappear with time, some of them are still well visible. Examining these traces, KSE performed a really huge amount of the work, and its results have been published in a series of collections of scientific papers. Nonetheless these results remain virtually unknown in the West and not fully assimilated in Russia.
In the course of these investigations the problem of the Tunguska explosion has evolved into a multidisciplinary field of research, with its own research community, a set of publications, research methodology, etc. In respect of the "meteoritic establishment" (personified in the KMET), this community turned out to be to a large extent alternative, since it was ready to consider every hypothesis of the TSB origin, even the extraterrestrial starship. However, the ITEG combines its unconventional research strategy with strictly normal, rigorous, scientific research methods. Thus, the Group has been performing a normal scientific investigation of an anomalous phenomenon. This investigation can be considered exemplary in respect of its scientific level, seriousness and unbiasedness. If we associate science with these distinctive features (and not with the automatic following of paradigmatic models even when they are obviously inconsistent with the phenomena under investigation), then we are dealing here with nothing but normal science.
I would also like to emphasize the importance of the not-so-peaceful coexistence of the "technogeneous" (or "artificial", A-) and "natural" (N-) conceptions of the TSB nature for the development of the Tunguska studies. In fact, their entire history, beginning from 1946 (the year when Alexander Kazantsev published his hypothesis) is a history of the A-N competition. The alternatives "nuclear-thermal" (explosion) and "artificial-natural" (body) have remained the key-note in the whole Tunguska affair, especially in the work of the research team led by Alexey Zolotov (at first in the town of Oktyabrsky, Bashkir ASSR, and later in Kalinin - now Tver). In particular, Zolotov succeeded in establishing, even on the basis of that empirical material which was collected by the middle of the 1960s, the most important point of the affair: that the forest destruction was made by the blast, and not by the ballistic wave.
Empirical facts gathered by the ITEG and other Tunguska investigators during the last decades, although sometimes looking "strange," are well established, and no model of the phenomenon may ignore them. What's more, any conception that does ignore these facts cannot be considered as serious and scientific. Unfortunately, many theorists (especially - although not only - Western ones) try to solve this enigma in a flash, being aware only of two facts: a) in 1908 something flew over Western Siberia; b) this "something" exploded. Sorry, gentlemen, there is much more in this story than just that.
3. Stranger and stranger...
Now, what do we know about the Tunguska explosion and the Tunguska space body? And - no less important! - what do we still NOT know?
1. The explosion on the Podkamennaya Tunguska was just the most striking event in the set of large-scale atmospheric anomalies which occurred in the summer of 1908 and were probably interrelated.
2. The main explosion occurred in the atmosphere, at an altitude of 5 to 7 kilometers. The area of the leveled forest has peculiar contours (something like a gigantic butterfly) and a complex structure. In general the forest fell strictly radially, but near the epicenter there are local deviations from the radial pattern, which enables assumption of the existence there of at least two or three subepicenters.
3. There are no meteorite craters in the region of the explosion, nor any substance that could be identified with that of the Tunguska space body. The meteoritic dust that was found on the site does not differ from the usual background fall of extraterrestrial matter.
4. The axis of symmetry of the fallen forest field is directed at 81° W of the true meridian. It is interpreted as the imprint of the ballistic shock wave of the TSB at the final stage of its flight, that is immediately before the explosion. It is essential to note that this wave was rather weak, leveling none of the trees and just introducing some little deviations in the radial pattern of forest falling. The latter was in itself fully due to the effect of the blast wave. This points to the fact that the speed of the Tunguska body at the final stage of its flight was relatively low. Alexey Zolotov has estimated this speed at 1.2 kilometers per second. Therefore the explosion was due to the internal energy of the body, not to the energy of its motion.
5. Concentration of this energy approached that of nuclear explosions, and no less than 10 percent of it was released as the flash. This suggests some kind of nuclear reaction, but what kind it was remains unknown. No firm evidence of such a reaction has been found in soil and vegetation in the region of the explosion. However:
5.1. Directly under the path of the Tunguska space body, thermoluminescence of minerals has substantially increased. This can have been due to hard radiation, emitted in the course of the flight and, possibly, at the instant of the explosion.
5.2. A complex set of serious ecological consequences has been revealed in the region of the explosion. These are: first, a very fast restoration of the forest after the catastrophe and accelerated growth of trees (both young and those which survived the incident); second, a sharply (in 12 times!) increased frequency of mutations in the local pines. Both of these effects tend to concentrate towards the "corridor" of the Tunguska body flight path. As many other anomalies in this region, the genetic impact of the phenomenon is also of patchy character. There was also discovered a rare mutation among the natives of the region, which arose in the 1910s in one of the settlements nearest to the epicenter (Strelka-Chunya).
5.3. According to Dr. Nikolay Vasilyev, medico-ecological examination of the state of health of native inhabitants of Evenkya (the territory of the Evenks or Tungus) reveals population-genetic effects similar to those observed in the regions affected by nuclear weapon tests (the Altai Territory, the Lower Ob', the areas around the coast of the Kara Sea).
These facts (as well as the local magnetic storm that started after the explosion) count in favor of the nuclear character of the Tunguska explosion.
6. Apart from the "main" explosion at a relatively high altitude, there were a number (three, or four) of "additional" low-altitude and, probably, low-power explosions. This is borne out both by fine structure of the fallen forest field and by testimonies of some eyewitnesses who found themselves in the immediate vicinity to the epicenter:
Chuchancha and Chekaren, two Evenk brothers belonging to the kin of Shaniaguir, were at the moment of the explosion sleeping in their chum (a tent of skin or bark) situated on the bank of the Avarkitta river, very close to the epicenter. Suddenly they were woken by a few tremors, whistling and a loud sound of the wind. "Both of us were very much frightened, - told Chuchancha in 1926 to the well-known ethnographer and public figure Innokenty Suslov who spent many years working in Evenkya. - We began to call our father, mother and third brother, but nobody replied. A loud noise was heard from the outside of the chum; we understood that trees were falling. Chekaren and me, we got out from our sleeping bags and were going to go out of the chum, but suddenly there was a very great clap of thunder. This was a first blow. Earth trembled, a strong wind hit our chum and threw it down. The elliun [the skins covering a chum] rode up and I saw something terrible: trees were falling down, their pine-needles burning. Dead branches and moss on the ground were burning as well.
Suddenly there appeared above a mountain, where the trees had already fallen down, bright light like a second sun. At the same moment a strong agdyllian, a thunder, crashed. This was a second blow. The morning was sunny, no clouds, the sun shone as always, and now a second sun!
With an effort I and Chekaren crawled out from under the chum poles and elliun. After that we saw a flash again appear and a thunder crash heard again overhead, although in another place. This was a third blow. Then there was a new gust of wind that knocked us down and we knocked ourselves against a leveled tree.
[A short time later] Chekaren cried out: "Look up!" and stretched his hand upward. I looked in this direction and saw new lightning, with an agdyllian. But its sound was not so loud as before. This fourth blow was like a usual thunder.
Now I can remember there was a fifth blow, but rather weak and far away from us." This last explosion took place somewhere far in the north.
7. The zone of the radiant burn of trees is also "butterfly-like" in shape, its axis of symmetry approximately coincides with the "ballistic" one. Besides, it is somewhat extended along the path of the Tunguska body; it appears that the latter was moving and exploding (or at least emitting powerful electromagnetic radiation) over the last 20, or so, kilometers. This is not in good accordance with the strict radial pattern of forest falling, and therefore we should probably assume that the source of the flash was not identical with that of the blast wave. The radiantly burned vegetation is arranged patchily, that is areas thermally seriously damaged and areas free from any thermal influence are intermittent. A workable model, explaining this peculiarity, would be a host of powerful "thermal rays," rather than a simple fireball.
The fact that Chuchancha and Chekaren (as well as some other Evenks) have survived near the epicenter of 30 to 50 megaton explosion seems also to favor the highly anisotropic character of the latter.
8. Some local geochemical anomalies have been discovered at the epicenter of the Tunguska explosion. There were found substantial shifts in isotopic compositions of carbon, hydrogen, and lead. The soil is also enriched with rare earths (samarium, europium, terbium, ytterbium, etc), as well as with barium, cobalt, copper, titanium, and some other elements. As was supposed by the late Dr. Sergey Dozmorov (a very gifted chemist from Omsk, Russia, who tragically died several years ago), these results may indicate that the TSB had contained some appreciable quantities of superconducting high-temperature ceramic made on the basis of the following combination of elements: barium - a lanthanide - copper. Such ceramic keeps superconductivity up to the temperature of liquid nitrogen (-196°C) and can be used for constructing very effective energy and information storage devices. Obviously, such a substance cannot be natural.
9. The combination of the "butterfly-like" shape of the area with the general radial pattern of forest falling suggests that the Tunguska body consisted of two different parts: an "explosive" and a non-uniform "shell," which gave rise to peculiarities of the blast wave shape. Thereby it resembled an artificial construction. As Alexey Dmitriev and Victor Zhuravlev note, the shape and structure of the fallen forest field can be easily explained if we assume that the shell had symmetric zones of increased and reduced strength of material. Another workable model would be a cone-shaped mass of explosive having cumulating hollows and a detonator in its forward part.
10. What path the Tunguska space body followed through the atmosphere remains to a large extent unclear. Immediately before the explosion it was moving almost exactly east to west. The witnesses' testimonies that were collected in the 1960s do in fact bear out this variant. Yet the witnesses' testimonies gathered in the 1920s suggest with equal likelihood that the body might have arrived from the south or "at best" from the south-east. This evidence cannot be easily rejected since it was obtained shortly after the event. Attempting to find a way out of this deadlock, Dr. Felix Zigel (a well-known scientist and the father of Soviet ufology) in 1966 suggested a possible maneuver of the Tunguska body at the final stage of its flight. However, the eastern variant of the path has been traced as far as the Lena river. This casts doubt on the possibility of a maneuver at least for this body. Shouldn't we assume that there were several bodies moving from different directions towards more or less the same final point?
11. And last but not least: what was the lot of the Tunguska body (or bodies) after the explosion? The hypothesis of a "ricochet" of the TSB, put forward in the early 1930s, was rejected, in particular, because the researchers understood well: the Tunguska space body had no chance of surviving such a powerful explosion. It may be so, but nonetheless, as was noted by Dr. Gennady Plekhanov, the imprint of the ballistic wave on the fallen forest is observed even beyond the epicenter, approximately in the same direction as before it. Therefore some part of the body (or just one of the bodies) might have continued its flight after having taken this "fiery bath."
A noteworthy fact: among other interviewed eyewitnesses of the Tunguska explosion, there was an elderly Evenk man named Ivan Aksenov, a shaman, who after the revolution of 1917 had been hiding for many years in taiga from the Soviet authorities. At the moment of the catastrophe the eyewitness (then 24 years old) was on the Chamba river, hunting near the mouth of a tributary of the Chamba, that is some 40 km to the south from the catastrophe epicenter. After the explosion he had seen an object flying down the Chamba, i.e. generally north to south. He called the object a "devil." "As I came to myself, - recalled Aksenov in 1967, - I saw it was all falling around me, burning. No, that was not god flying there, it was really devil flying. I lift up my head - and see - devil's flying. The devil itself was like a billet, light color, two eyes in front, fire behind. I was frightened, covered myself with some duds, prayed (not to the heathen god, I prayed to Jesus Christ and Virgin Mary). After some time of prayer I recovered: everything was clear. I went back to the mouth of the Yakukta where the nomad camp was. It was in the afternoon that I came there..." The devil was going faster than airplanes now do. While flying, it was saying "troo-troo" (which were not loud).
4. On the way to the truth
From all the aforesaid it follows that intricacy and complexity of the Tunguska phenomenon far exceeds the limits of the simplest models still existing in popular-science and even scientific literature. It certainly appears that the basic tendency of the results obtained during the years of Tunguska investigations favors the artificial nature of the Tunguska space body and at least unconventional character of its explosion. The technogeneous hypothesis is thus coming to the fore in the Tunguska studies. But of course, it doesn't have to be limited by its initial version - that is, by the hypothesis of an accidental crash of an extraterrestrial spaceship. It might well be not accidental.
When working in the middle of the 1970s with Alexey Zolotov and his team, the present author developed the so-called "battle model" of the Tunguska phenomenon. According to it, there happened in 1908 an aerospace battle between two or more alien spaceships, after which one of them survived and flew back to the space. Of course, I do not mean this is the final solution of the Tunguska mystery, but as a working instrument this model seems to be helpful. Whether or not it is correct, only time will tell.
Certainly, we have still much to learn about the flight and explosion of the TSB. Perhaps one day in the future it will be possible just to deduce a convincing model of the phenomenon directly from the facts accumulated. To bring this day closer, Russian and Ukrainian scientists are trying to develop their studies in this area even in the hard conditions that still prevail in their countries. Scientists and anomalists in other countries could help them as well. Anyone wishing to participate in this search is welcome to contact the author of this paper through his webpage on Facebook
. There seems to have been in the Tunguska sky much more than we can at present imagine...
1. Rubtsov, V. The Tunguska Mystery. N.Y.: Springer, 2009 & 2012 (in English).
2. Bidyukov, B. F. (Ed.) The Tunguska Phenomenon: Multifariousness of the Problem. Novosibirsk: Agros, 2008 (in Russian).
3. Vasilyev, N. V. The Tunguska Meteorite: A Space Phenomenon of the Summer of 1908. Moscow: Russkaya Panorama, 2004 (in Russian).
4. Bronshten, V. A. The Tunguska Meteorite: History of Investigations. Moscow: A. D. Selyanov, 2000 (in Russian).
5. Zhuravlev, V. K., and Zigel, F. Y. The Tunguska Miracle: History of Investigations of the Tunguska Meteorite. Ekaterinburg: Basko, 1998 (in Russian).
6. Dmitriev, A. N., and Zhuravlev, V. K. The Tunguska Phenomenon of 1908 as a Kind of Cosmic Connections Between the Sun and the Earth. Novosibirsk: IGIG SO AN SSSR, 1984 (in Russian).
7. Zolotov, A. V. The Problem of the Tunguska Catastrophe of 1908. Minsk: Nauka i Tekhnika, 1969 (in Russian).
8. Tronov, M. V. (Ed.) The Problem of the Tunguska Meteorite. Vol. 2.Tomsk: University Publishing House, 1967 (in Russian).
9. Plekhanov, G. F. (Ed.) The Problem of the Tunguska Meteorite. Tomsk: University Publishing House, 1963 (in Russian).
10. Krinov, E. L. The Tunguska Meteorite. Moscow: Academy of Sciences of the USSR, 1949 (in Russian).
Tunguska Home Page of Bologna University
“On June 30th, 1908, something exploded 8 km above the Stony Tunguska river. About 2150 square kilometers of Siberian taiga were devastated and 80 millions trees were overthrown. Up to now, it is not clear whether the great explosion was due to a comet or an asteroid or something else. We are searching for an answer.”
The Tunguska Meteorite
Website of members of the Independent Tunguska Exploration Group (ITEG). “We wish the ITEG to live and continue its investigations. Its work will certainly inspire future generations of Tunguska enthusiasts…” In Russian.
The Tunguska Phenomenon
The richest ever collection of materials on the history and current state of the Tunguska investigations. In Russian.
The Tunguska event
Wikipedia, the free encyclopedia.
An informative website containing many valuable Tunguska-related materials, including wonderful photographs and the Catalog of the Tunguska Eyewitness Reports. Authored by Vitaly Romeyko. In Russian.
The National Nature Reserve Tungussky
The National Nature Reserve Tungussky was established in 1996 by the Federal Government of Russia. It occupies an area of 3000 square kilometers and is kept in its primordial state. Generally in Russian state nature reserves, visits by tourists are forbidden, but the Tunguska nature reserve is exempted from this rule and everyone wishing to visit this area with its unforgettable aura can do so. In Russian.
The Tunguska Phenomenon
This website provides information about Tunguska investigations conducted by Krasnoyarsk Branch of the Independent Tunguska Exploration Group. In Russian.