by Academician N.V. Vasilyev
The term "Tunguska meteorite fall"
refers to the cosmic phenomenon that was observed on June 30, 1908,
about 7 a.m. of the local time in Central Siberia, over
Krasnoyarsk Territory, Irkutsk Region and
Yakutiya [I ]. The most remarkable feature of the event
was an explosion of a space object of unknown origin which was
moving generally SE to NW and was seen in many settlements of the
The flight of the object was attended by sound, seismic and
electrophonic effects which covered a vast territory [1-4], and it
was equal to the whole set of manifestations of a bolide of 22m -
17m of the stellar magnitude. Its brightness was comparable to that
of the Sun, but there was no smoky trail
characteristic of large iron meteorites. Still, many witnesses
noticed a trail of iridescent bands looking like a rainbow .
At the moment when the body was flying at the approximate altitude
of 5.5 to 8 km over the area with the coordinates 60º 53’ N, 101º
54’ E (70 km to NW from the little trading station of Vanavara,
Krasnoyarsk Territory, not far from the
Podkamennaya Tunguska river), there occurred an explosion,
or, more precisely, explosion-like energy release.* The TNT
equivalent of the effect is estimated as 10-40 megatons, the energy
being 4.2? 1023 to 1.7? 1024 ergs [5-8]. There is some evidence
suggesting that following the explosion-like energy release at least
a part of the Tunguska Space Body (TSB) continued to move in the
"pre-explosion" direction upwards [9; 10].
The TSB "explosion"
gave rise to a seismic wave recorded in Irkutsk,
Tashkent, Tbilisi and Jena
, as well as pressure disturbances which traveled around the
globe [3; 11; 12]. In addition, 5.9+0.9 min. (or, according to
another estimate, 6.6 + 0.2 min) after the ’’explosion", local
magnetic storm began which persisted for more than four hours and
was similar to geomagnetic disturbances following nuclear explosions
in the atmosphere [13-16].
The shock wave of the Tunguska explosion leveled 2150
+ 25 km2 of taiga [9; 17], and the flash burnt vegetation
over an area of about 200 km [18; 19]. The Tunguska explosion
resulted in a major forest fire covering an area comparable with
that of fallen forest [20; 21].
It is noteworthy that the explosion on
the Pod-kamennaya (Stony) Tunguska was just the
most striking event in the set of natural anomalies which occurred
in the summer of 1908 and were probably interrelated. It is now
known  that beginning on June 23, 1908, atmospheric optical
anomalies were observed in many places of Western Europe, the
European part of Russia and Western Siberia. They gradually
increased in intensity till the 29th of June and then
jumped to their peak in the early morning of the 1st of
July. These anomalies which are described in detail in Refs. [22 ]
and  included unprecedented active formation of mesospheric
(silvery) clouds, bright "volcanic" twilights ("variegated
afterglows"), disturbances of the normal travel of the Arago
and Babinet neutral points, supposed increase in the emission
of the night sky, and unprecedented intense and long solar halos.
Later, after July 1, these effects exponentially reduced; still some
after-effects took place up to late July of 1908.
The area involved in these phenomena included a considerable part of
the Northern Hemisphere and was bounded by the Yenisey river
in the East, by the Tashkent - Stavropol - Sevastopol - Bordeaux
line in the South, and by the Atlantic coast in the West.
In August of the year the Western Hemisphere saw a decrease in the
air’s transparency [24 ] which was due, as V.G.Fesenkov
believed, to atmospheric circulation of the Tunguska explosion
products. It has been shown recently that along with the Tunguska
aerosol cloud, there was simultaneous circulation of products of
destruction of another large bolide which entered the Earth’s
atmosphere in May of 1908 . Superimposition of these
effects makes their separate interpretation more difficult.
It should be also noted that the summer of 1908 was quite rich in
bright bolides in Siberia, as well as elsewhere [22; 26] (if one
compares that year with the years 1907 and 1909 ).
The Tunguska meteorite explosion area was found in the
20s by surface explorations of L.A.Kulik, as well as through
analysis of geophysical data performed by A.V.Voznesensky
. The chronology and findings of subsequent studies of this area
are described in Refs. [29-32].
The expeditions before World War
II that were headed by L.A.Kulik [1 ; 2; 33], as well
as post-war field works (since 1958 till now) found no
explosion-or impact-induced astroblemes or large fragments
of the TSB [34-37]. Active search for
finely-dispersed space material in the area of the
catastrophe, over 10,000 km2 , did not result in
discovery of a material to be reliably identified with that
of the Tunguska meteorite.
The meteoritic dust and similar
particles which were found on the site [38-41; 44] cannot be
now reliably differentiated from fluctuations of the
background fall of extraterrestrial matter. However, there
have been revealed in the area of the catastrophe some
biogeochemical elemental and iso-topic anomalies which may
be related to the event under discussion [42≈47].
Interpretation of these anomalies is still more complicated
since the epicenter of the Tunguska
explosion almost ideally coincides with the
center of an ancient volcano
(click image right) , whose lava flows and
thermal ejections undoubtedly affected essentially formation
of the biogeochemical situation in the region. The post-war
expeditions revealed a complex set of ecological
consequences of the Tunguska catastrophe,
explosion epicenter is right in the middle of the ancient
volcanic crater, which after its discovery in 1972 got the
name "Kulikovskii". This volcano is part of Khushminskii
Satellite photo (in near-infrared band) of Tunguska
epicenter marked with a "star".
1) accelerated growth
of young (post-catastrophic) trees and those which survived the
2) population-genetic effects, chiefly at the
epicenter and along the TSB trajectory [52; 53]
This is a general outline of the
Tunguska phenomenon which, upon thorough study, proves to be
principally different from other impact phenomena.
The many hypotheses proposed to explain the Tunguska phenomenon
can be subdivided into two groups. One will include those based on
the concept of transfer of the kinetic energy of the Tunguska
body into the shock wave energy. The other group consists of
hypotheses emphasizing release of the internal energy of the body,
chemical or nuclear.
Among the hypotheses of the former group, worthy of detailed
consideration are primarily those involving concepts of
asteroidal (an iron or stone asteroid, or a
gigantic carbonaceous chondrite) or comet TSB
nature. These can be classified as hypotheses based on the classical
concepts of the minor bodies of the Solar System.
The hypotheses of the latter group assume a special type of the
nature of TSB, different from asteroids or comets.
These include the hypotheses of the antimatter nature of the
TSB , of the Tunguska meteorite as a
microscopic black hole , of a "solar energophore"
 and even of technogeneous origin of the TSB
The very fact of the existence of the so diverse views suggests a
situation where the phenomenon in question is difficult to explain
in all its aspects. Indeed, profound analysis of the factual data on
the phenomenon evidences its structural complexity and seeming
contradictoriness which restrict its interpretation in traditional
terms. It is thus suitable to dwell upon certain most serious
difficulties which are to be coped with in any attempt to construct
an integrated concept of the Tunguska phenomenon.
On the direction of the TSB flight
some peculiarities of the evidence of eye-witnesses who were
close to the Tunguska explosion epicenter
some specific features of destruction of the forest at the
Tunguska explosion epicenter
The energy balance of the Tunguska
the geophysical effects of the Tunguska catastrophe
1. On the direction of the TSB flight
The first investigators of the Tunguska meteorite (L.A.Kulik,
E.L.Krinov, and I.S.Astapovich [1; 2; 3 ]) who
analyzed comparatively fresh evidences of the flight of the
TSB on the Angara river did not doubt that it
had moved generally from the south to the north, though there were
three versions of its trajectory (the southern one, proposed by
L.A.Kulik, the south-eastern by E.L.Krinov and the
south-western by I.S.Astapovich). By the early 60-s it was
Krinov’s trajectory, namely 135º east of the true meridian, that
was considered the most realistic.
Later however, as more information was accumulated on the vector
structure of the fallen forest field [9; 17; 59], a "corridor"
of axially symmetric deviations of the vectors of the forest falling
from the dominating radial pattern was revealed, and this deviation
was interpreted as the track of the ballistic wave. The direction
of, the "corridor" which was initially estimated as
111º E from N (114º east of the true meridian)  was later found
to be 95º E from N (99º east of the true meridian) , which
roughly coincides with the axis of symmetry of the radiant burn area
. In this period of time, V. G.Konenkin  and later
other investigators [61-63] questioned old residents of the area who
had lived in the upper reaches of the Nizhnyaya (Lower)
Tunguska in 1908 (where there was no questioning in
the 20s and 30s). This resulted in the conclusion that TSB
had been observed in the said area as well, the analysis of the data
suggesting that the body moved from the ESE to the WNW, i.e.
by the path coinciding with the projection of that of the TSB,
as found on the basis of analysis of the vector picture of the
fallen forest area. This coincidence caused revision of the notion
of the TSB path, and since the year 1965 the ESE-WNW (in
fact, even E-W) version has been accepted in literature. For some
years it was assumed to be finally true.
A grave disadvantage of the calculations of TSB path
before the mid-80s was that there were analyzed only some separate
groups of eye-witnesses’ accounts obtained by different researchers,
in different periods of time, and not the whole body of evidence.
Publication of the catalogue of eye-witnesses information 
enabled analysis of the whole event. This was done in Ref.  and
corroborated the considerations expressed earlier in Ref.  and
also by I.S.Astapovich . Two fundamental facts were
established in particular:
1. The total
combination of evidence given by "eye-witnesses of the
Tunguska fall" contains in fact information on at
least two (most likely more) large day-time
bolides. It is important that the "images" of the "Angara"
and the "Nizhnyaya Tunguska" bolides are
quite different and everything seems to indicate that they
belong to different objects.
2. The trajectory calculated on the basis of
evidences of witnesses of the "Angara" phenomenon and
corresponding most likely to its version proposed by
E.L.Krinov  deviates considerably from that determined by
analyzing of the vector structure of the forest fall area and
the radiant burn area [9; 19]. Indeed, evidences of the
Angara eye-witnesses, including the report of a district
police officer, strongly suggest that the bolide flew "high
in the sky", which is hardly consistent with the path 99º E
of the true meridian. On the contrary, the data obtained on the
Nizhnyaya Tunguska river, though agreeing with the
configuration of the destruction area, are in contrast with the
An extra complication is that
Nizhnyaya Tunguska data suggest virtually
unambiguously that bolide’s flight took place in the afternoon,
unlike those of the Angara which refer to the early
Attempts to resolve the conflict between the data face with
considerable problems. If the Angara and Nizhnyaya
Tunguska observations are due to different bolides, which
is most probably so, then with which of them the destruction area
originally explored by L.A.Kulik is associated? Judging by
the destruction area configuration, the most probable candidate is
the eastern (Nizhnyaya Tunguska) bolide.
However none of TSB investigators doubts that the
explosion at the distance of 70 km from Vanavara
occurred in the early hours of the day, not past midday .
Moreover, there is no direct proof that the Nizhnyaya Tunguska
bolide was observed in the year 1908, inasmuch as this event
was not recorded in any official documents, unlike the Angara
Besides, even assuming the area of the leveled forest, discovered by
L.A.Kulik, to be due to the Nizhnyaya Tunguska bolide, it
remains unclear where the Angara bolide fell, then.
Throughout the Tunguska "meteorite" study there was no
doubt the latter had in fact exploded in the Vanavara region...
But if the forest leveling was caused by the Angara bolide,
how does it fit the direction of the "corridor"
impressed in the area of the fallen forest by the TSB
In the search of way out of this maze, more than one approach has
been tried. Some researchers, preferring direct physical evidence,
practically ignored eye-witnesses’ testimonies as an unreliable
subjective material. This approach could be agreed with to some
extent, if it were a matter of a few inconsistent testimonies, not
many hundreds of independent reports. Besides - what is very
important - the testimonies of the year 1908 include official
documents of the time, whose authors were responsible to the
authorities for their trustworthiness. For this reason, the
eye-witnesses’ reports should be regarded as a material equal to
other data sets or at any rate not to be ignored, even if they do
not conform to some speculative arguments.
Other investigators tried their best to combine the Angara
evidence, the Nizhnyaya Tunguska data and the geometry
of the destruction area . The results were rather dubious,
strained, and quite different in this from the sufficiently
unambiguous and clear picture which is provided when the two groups
of eye-witnesses’ reports are analyzed separately.
Then, F.Yu.Zigel  introduced the concept of a "manoeuvre"
made by the TSB, assuming it to have moved initially
in a path close to that calculated by E.L.Krinov  and
then, describing an arc, entered the space over the interfluve of
the Nizhnyaya and Podkamennaya Tunguskas
and took an eastern path which led it to the "explosion".
These contradictions have not been reconciled. It seems probable
that the eastern group of eye-witnesses’ evidence is not directly
related to the Tunguska bolide and that the latter moved in a
trajectory-close to that calculated by E.L.Krinov . The
cause of the incompatibility of the bolide path projection
with the data of the Angara eye-witnesses’ group remains
unclear. Yet it should be borne in mind that the identity of the
axis of symmetry of the observed forest destruction pattern with the
projection of the bolide path that appears almost
self-evident to the Tunguska meteorite investigators is only
an assumption of high probability, rather than an established truth.
The axially symmetric "corridor" is the trace of the
ballistic wave where it touched the earth surface’, it remains
essentially an open question what its initial space position was and
whether it could change for some reason or other.
However, the problems associated with
the TSB path parameters are not only these. Most of
the authors who studied this question conclude that the slope of the
TSB path was relatively small (some 15º) [1; 66; 67]. Still,
modeling experiments [68; 69], as well as results of mathematical
simulation of the Tunguska explosion parameters [70;
71] evidence that the slope of the final path section was most
probably 40º. The transition of the TSB from the
comparatively flat path to the steep one ("the peck") seems to have
taken place as the bolide approached the spot of the
explosion: it might be due, as is held in Refs. [72; 73], to
avalanche breaking of the "meteorite", enlargement of its frontal
surface and increasing resistance of the air.
Especially embarrassing is the fact that the "corridor",
this impression of the ballistic wave on the forest, is observed, as
has been recently shown, even beyond the epicenter of the explosion,
as if roughly-continuing the direction of the TSB flight
. The most reasonable explanation is assumption of a ricochet of
the TSB part which survived the explosion and
continued its flight, maintaining, to some degree, the same
trajectory. The question however arises if this assumption satisfies
the requirements of the theory of the strength of materials.
As was mentioned above, the TNT equivalent of the Tunguska
explosion is estimated as 10-40 megatons, the temperature of the
center of the fire ball measuring at least tens of thousands of
degrees Kelvin . What must have been the characteristics of the
TSB substance to withstand this "fiery font" and
retain compactness and ability to ricochet? And how does it go with
the above concept of the TSB consisting of comet ice
or a silicate material, suggested by the first group of hypotheses
to account for the Tunguska phenomenon?
Thus, analysis of materials characterizing the TSB
path suggests its rather complex nature. It is not improbable that
the Tunguska object moved in a non-ballistic trajectory.
2. On some peculiarities of the evidence of eye-witnesses who
were close to the Tunguska explosion epicenter
The TSB (or some part of it) exploded over a sparsely
populated area, and for this reason only few eye-witnesses of the
event found themselves close enough to the scene of the disaster.
(The number of the victims of the Tunguska catastrophe
was also very limited.) Besides Russian eye-witnesses who lived at
the Vanavara trading station (70 km SE of the
epicenter), whose reports were collected by L.A.Kulik
(see: [1 1], there were within 40 km around the epicenter detached
nomad camps of the Evenks (Tungus)
on the Nizhnyaya Dilyushma, the Avarkitta
(or possibly the Makikta, a right tributary of the
Chamba river) and near the mouth of the Yakukta river
(40 km to the south of the epicenter, close to where the so-called
Kulik’s path intersects the Chamba river). The
testimonies of the witnesses from the Nizhnyaya Dilyushma river
were published as early as in the 1920-s  and contain memories
of the fire in the forest and fallen trees. These are well known and
have been commented on by specialists more than once. As regards the
testimonies of the Evenks who had been on the Avarkitta
and the Yakukta, those were published much later and contain
some strange details that seem to deserve special attention. These
details are definitely queer, and the reader finds himself before
the alternative: either deny them as obviously absurd, or - be they
believed if to a certain degree - assume that our ideas of the
physics of the Tunguska explosion are wrong.
The first of these reports was communicated by the well-known
ethnographer and public figure I.M.Suslov who spent many
years working in Evenkiya (the territory of the
Evenks or Tungus). In 1925, during the "suglan"
(kin council), he questioned those people who had seen the
Tunguska event [ 76 ]. Much later, in the 60s, being a
pensioner, I.M.Suslov informed the Siberian Commission on
Meteorites and Cosmic Dust that he had some unknown materials on
the problem which he was ready to make public in a collection of
papers on the topic of the Tunguska meteorite. Shortly after
that he gave them a large manuscript, which was edited and abridged
by V.E.Shnitke and then published in the collection The
Problem of the Tunguska Meteorite in 1967 [ 77 ]. It remains
unclear why Suslov had not had it published before. Equally
unknown have remained the initial records on which the paper was
based. No original notes on the topic were discovered in Suslov’s
papers after the man’s-death. The impression is that the paper was
written by himself on the basis of either his personal memories or
some notes now missing.
I.M.Suslov’s paper is a detailed presentation of a report of
the Evenks of the Shenyagir kin who were at the moment
of the Tunguska explosion in the middle part of the
Avarkitta river. The scope of the present paper is not
sufficient to completely present this report, but its essence can be
summarized as follows.
There were five explosions, the second seeming to have
been the most powerful. Light flashes followed at an interval of a
few seconds and were seen at different spots of the sky. The last,
fifth explosion took place far in the north, somewhere near
the Taymura river. Trees began to fall and the fire
began after the first explosion, while the Evenks were
in their "chums" (tents of skin or bark), the latter being
thrown down. There were traumatized people.
The data communicated by I.M.Suslov are quite detailed and
enable the whole phenomenon to be estimated as lasting no less than
Another report was conveyed to the TSB investigators
by V.G.Konenkin, a local inhabitant and school teacher of
physics in Vanavara, who had questioned old residents
of settlements of the upper reaches of the Nizhnyaya Tunguska
and the Tunguska-Chunya Region of Evenkiya for
several years. Among those questioned was an Ivan lvanovich
Aksenov, an elderly Evenk man, who was said to have
been a shaman hiding for many years in taiga from the
authorities. The entire record of I.I.Aksenov’s account is
presented in Ref. . At the moment of the catastrophe the
eye-witness 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. A particular feature of
Aksenov’s account (agreeing otherwise with the early evidence of
Vanavara residents that Kulik had heard as far
back as the 20s), is the assertion of the eye-witness that 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, he told
Konenkin, I saw it was all falling around me, burning. You
don’t think, Viktor Grigoryevich [V.G.Konenkin],
that was god flying, 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..."
Afterwards I.I.Aksenov repeated
his account in the presence of V.G.Konenkin and
V.M.Kuvshinnikov, an active participant of the Tunguska
expeditions. In this case, however, he said that he had seen the
"flying devil" not during hunting but in the
afternoon, when already in the camp near the mouth of the
Yakukta, also a tributary of the Chamba. The
devil was going flying southward along the Chamba. It was
going faster than airplanes now do. While flying, the "devil"
was saying "troo-troo" (which were not at all loud).
Later, during repeated questioning in Vanavara, he did
not insisted on having seen the "devil", repeating
nevertheless the other evidence. When evaluating Aksenov’s
account it should be borne in mind that the eye-witness regarded the
expedition people with distrust, considering them representatives of
the "authorities", and thus the contact with him was not at
all easy. On the contrary, his relations with V.G.Konenkin
were fairly confidential, the latter being a local resident and a
half-caste. Therefore, in our opinion, the first version appears
to be more authentic, because Aksenov does not seem to
have had reasons to lie to Konenkin.
What is the true meaning of this queer story and how
trustworthy is it, it is now hard to say. Without overrating the
significance of individual eye-witnesses’ evidence, note
nevertheless that at least two reports provided by those (very few)
eyewitnesses who were close to the epicenter of the Tunguska
explosion are really peculiar.
3. On some specific features of destruction of the forest at
the Tunguska explosion epicenter
It has been ascertained that the main cause of forest destruction in
the area of the Tunguska catastrophe was powerful energy
release that took place at an altitude of 5.5-8.0 km. It must have
been thus a huge explosion in the air which gave rise to a spherical
shock wave, with the front at the epicenter generally parallel to
the earth surface and inclined to it away from the epicenter. Thus,
at the latter the vertical component of the shock wave was mainly
active, while away from it the horizontal component was ever
increasingly dominant, its action most pronounced in the area of
interference of the incident and reflected waves .
As a first approximation, this is indeed so. Around the catastrophe
epicenter there is a vast (about 8 km across) area of what is called
"telegraphnik" (that is, looking like a forest of telegraph
poles) - the dead forest, scorched and devoid of branches, but trees
standing upright. This is the zone of action of the blast wave
vertical component. Outside this area forest is put down radially,
to distances from 12 to 40 km or more in various directions
(see image below). This is, in its
turn, the area of action of the blast wave horizontal component.
If the above model is fully correct, then, first, at the explosion
epicenter there must be no radial forest falling, and second, the
destruction pattern should be generally uniform.
The real situation is, however, essentially different. Firstly, even
at the epicenter forest was not destroyed completely. Within 5-7 km
from the epicenter, many small groups of trees survived [ 78 ],
mainly of larches. Topography of such groups is not quite definite,
though some of them are in shallow valleys between hills or along
rivers and brooks. These groups of trees have attracted attention of
investigators more than once [ 1; 4; 79] since as early as the times
of Kulik; however attempts to account for them based on the
relief features have not yielded unambiguous results.
The highest altitude above sea level of
the whole area is 593 m, which, in the case of explosion at an
altitude no less than 5.5 km, enables treating the whole area as a
plane. At the same time, the very fact of existence of these groups
and their patchy arrangement seem to suggest high non uniformity
of the action of the kinetic factors responsible for destruction
of forest at the catastrophe epicenter. This assumption is also
supported by some other facts. According to calculations  and
observations in the field , the thermal pulse at the epicenter
must have been 15 to 55 cal cm-2. This is certainly
sufficient to singe cedar branches which are highly sensitive to
thermal influences. Meanwhile, there is a group of cedars that
survived the Tunguska catastrophe on the bank of the
Southern Swamp, no more than 2.5 km from the
projection of the center of the light flash of the Tunguska
explosion , and right in the marsh there grow fir trees
which also survived the catastrophe. B.I.Vronski, in the year
1960, found on the surface of the Southern Swamp, practically
at the center of the projection of the light flash of the
Tunguska explosion, a lively larch, aged over 60 years.
The location of the tree made improbable its being screening at the
moment of the explosion.
The structure of the forest fall area in the immediate vicinity of
the epicenter also proved strange.
Firstly, the assumption of
the absence of radial tree falling here is not true. Surface
observations  evidence that there are some leveled trees in
this area as well, and the general radial character of the
forest falling is seen up to a "special point", viz. the
geometric center of the fallen forest area, as calculated by
V.G.Fast [17 ].
Secondly, Kulik’s interpretation of the fallen
forest area on the basis of the large-scale aerophotography of
1938 not only corroborated the complex vector structure of the
epicentral area, but also enabled assumption of the existence
there of at least two or three subepicenters [ 83 ].
Thirdly, the vector structures of the forest falling on
hill-sides facing the epicenter and the opposite ones are
essentially different, which is in poor agreement with the
assumption of the center of generation of the blast wave located
high above the earth.
Thus, the conclusion suggests itself
that along with great energy release 5.5-8 km above the earth, there
were a number of low-altitude (maybe even right above the surface)
explosions that contributed to the total picture of destruction.
This seems to be sustained by other data concerning in particular
the configuration of the zones of dead trees ("poles") 
in the central part of the area of the catastrophe and deposition of
aerosols immediately after the explosion.
Extraordinary variety of effects is also suggested by
analysis of radiant damages of trees . Literally beside trees
carrying distinct signs of thermal effects, there are many undamaged
trees, the cause being not always clear.
Thus, the features of destructions at the epicenter suggest in
homogeneity of the physical parameters of the Tunguska
explosion field and complexity of the physical processes
It should be emphasized that though the patchiness of the effects
associated with the Tunguska catastrophe has been noted in
literature more than once, its origin still as a rule has not been
discussed. This sees to be due to serious difficulties of its
interpretation in terms of the existing TSB models.
Note that the range of unusual features of local effects caused by
the shock wave and the thermal factors of the Tunguska
explosion is not restricted to what has been said, as
suggested in particular by the difficulties arising in
interpretation of fiery damages of trees injured during the
explosion-induced forest fire [86; 87].
4. The energy balance of the Tunguska explosion
The TNT equivalent of the Tunguska explosion was 10 to 40
megatons, comparable to the equivalent of the largest
thermonuclear explosions. Most energy was consumed by formation of
the shock wave, no less however than 10% released as the flash [88;
89]. It was formerly assumed that the high yield of luminous energy
was a typical feature of nuclear explosions and could attest to the
nuclear nature of the Tunguska explosion . Later
however it was shown that the same effects could attend also other
types of explosions, destruction of large meteoric bodies in
The energy of the Tunguska meteorite
has been independently estimated by analyzing seismo- and barograms
[7; 8] and using mathematical modelling. However, as has been
suggested by detailed works of V.P. Korobeynikov et al. [70;
90], the models of the Tunguska catastrophe based on the
assumption of transition of the kinetic energy into the energy of
the explosion do not provide adequate explanation to the observed
pattern of destructions and require, for the energy balance, a
certain "addition" from the TSB internal energy. This
aspect of the TSB problem has not been studied more
thoroughly. Thus, the question of the energy source of the
Tunguska explosion still remains open.
5. On the geophysical effects of the Tunguska catastrophe
One of the most striking geophysical effects associated with the
Tunguska catastrophe is the local geomagnetic disturbance
detected, shortly after the explosion, in Irkutsk,
though not recorded by any other geophysical observatory of the
world existing at that time [13; 14; 15]. This disturbance was
similar to some effects following middle - and high -altitude
nuclear explosions in the atmosphere [59; 91], but unlike the
latter, it exhibited a kind of lag, i.e. it occurred some time
after the explosion. It has provided the main argument to
account for the geomagnetic effect of the Tunguska "meteorite"
as due to entering of the shock wave the ionosphere: the lag was in
good accordance with the period of time required for covering by the
wave the distance from the explosion site to the lower ionosphere
Later, however, I.P.Pasechnik  has corrected the moment
of the Tunguska explosion on the basis of direct experimental
measurements of the velocity of the seismic wave between
Vanavara and Irkutsk. It has been found that
the "lag" was actually longer than 5.9 min. This fact,
thoroughly analyzed in Ref., is radically important to the
problem, inasmuch as the ensuing velocity of a shock wave in the
atmosphere is too low. Hence any mechanism accounting for this
effect as a consequence of arrival of the shock wave in the
ionosphere appears dubious. The question thus remains open, and
again, as in 1960, we are faced with the problem, without
Neither have been found adequate explanations to the changes of the
polarimetric properties of the twilight sky that appeared as
deviations from the normal travel of the Arago and Babinet
neutral points [22; 93]. This effect was noted on July 1st,
1908 in Arnsberg (Germany) and
disappeared by July 20th. Its characteristics differ from
the polarimetric disturbances observed after other cases of
atmospheric dusting. It is not improbable that such effects are
related to global development of mesospheric (silvery) clouds ;
there has been however no experimental verification of this
The explanation of the "light nights" of the late June and
early July, 1908, with recourse to dispersal of particles of a
comet’s tail in the upper atmosphere of the Earth  is not at
Indeed, according to this assumption, particles of the comet’s tail
were to be decelerated at the altitude of 200 km or more, whereas
most light anomalies formed at altitudes of 80 km (the zone of
formation of mesospheric clouds), 50-60 km (diffraction effects that
caused dawn and afterglow anomalies) and below that (atmospheric
halos) [22 ]. Besides, in this situation the tail of the "Tunguska
comet" should have been stretched over Canada [96
], but this was not so. Recently, there has been an attempt  to
ascribe the "light nights" of the summer of 1908 to transport
of material from the site of the explosion by stratospheric winds.
This assumption however is faced with two contradictions.
Firstly, at least at 10
places of Eurasia there were anomalous light
effects on the night of June 29-30, 1908. i.e. practically
simultaneously with (and even somewhat before) the
Tunguska explosion, which makes it impossible lo explain
the optical effects of June 30, 1908 as due to mechanical
transport of space aerosols from the site of the Tunguska
Secondly, in discord with this explanation is also the
sharp exponential decrease in the intensity of the atmospheric
anomalies after the 1st of July which well conforms
to the assumption of the dominating contribution of
photochemical reactions to formation of these. If,
alternatively, the main contribution were given by refraction
and scattering by aerosol particles, it would be more reasonable
to expect gradual decrease in the effects, as in the case of
volcano-induced optical anomalies .
Thus, explanation of the geophysical
effects of the Tunguska "meteorite" has been
faced with essential problems, the main being lack of a
satisfactory explanation of the geomagnetic effect.