Asteroid Comet Impact Hazards - Florida International University

GEOMAGNETIC EFFECTS AS ONE ASPECT OF THE TUNGUSKA EVENT
been recorded by the magnetographs in the Pacific Ocean atolls in 1958 following the thermonuclear
testing [Plekhanov et al., 1960]. Those new geomagnetic effects caused a sensation that year. But even
more sensational was the realization that almost an identical geomagnetic effect had occurred on our
planet 50 years earlier!
A detailed analysis of the magnetograms of a short term local geomagnetic storm recorded in Irkutsk
(970 km away from the Tunguska explosion) was published in the 1960s [Plekhanov et al. 1960;
Kovalevsky, 1963; Ivanov,1964; Zhuravlyov et al.,1967; Zolotov, 1969]. Independently, both
Kovalevsky and Zolotov made thorough comparisons of the Tunguska geomagnetic effects and the
effects of the high-altitude thermonuclear explosions in the Pacific. According to Zolotov, both the
effects occur in four stages. The initial stage is caused by a magnetohydrodynamic wave. It's energy
depends on the volume and temperature of the explosion plasma. The main phase is caused by the
diffuse motion of secondary electrons held within a magnetic trap. Primary electrons and ions are
generated by radioactive isotopes in the plasma of the fireball of a nuclear explosion. The reserve of the
radioactive isotopes accounts for the duration of the geomagnetic storm, since only the recombination of
electrons and ions would not permit such a storm to last more than an hour. For this reason, the duration
of the magnetic disturbance of a chemical explosion could not last longer than 10 minutes. However, the
geomagnetic storm caused by the Tunguska explosion lasted for 4 to 5 hours. This is the main difficulty
in explaining the Tunguska explosion within a cometary hypotheses frame.
Attempts to explain the unusual Tunguska geomagnetic effect, based on hypotheses about the blast wave
of the explosion affecting the ionosphere, were criticized in Zolotov's monograph and in a computational
paper by Zhuravlev and Demin [Zolotov, 1969; Zhuravlyov et al., 1967]. In 1969, a paleomagnetic
anomaly was discovered in the area of the Tunguska explosion [Boyarkina and Sidoras, 1974].
Computations made by the present author allowed suggest that this anomaly is the result of the first
stage of the geomagnetic storm of 30 June of 1908. The main stage of the storm could have been caused
by the shift of fast electrons along the magnetic force lines above Irkutsk (as happens during a nuclear
geomagnetic storm). Analysis of the regional geomagnetic storm of 30 June 1908 is very important to an
understanding of the Tunguska Event. The analysis of this unexpected effect leads to a conclusion of a
paradoxical nature: the first nuclear explosion occurred not in New Mexico in 1945, but in 1908 in
Tunguska! This "crazy idea" was published by Kazantsev in 1946. This type conclusion is a challenge to
the scientific paradigm of the 20th century. In this author's opinion, it is the reason for the geomagnetic
effect-a most significant and informative effect-being lost by the way and essentially forgotten, the
effect that is most likely to lead to understanding of the Tunguska phenomenon.
However strange it may seem, all theoretical calculations made on the bases of the cometary hypothesis
ignored this fundamental fact. The regional geomagnetic storm of 1908 is the evidence that either some
comets contain an unknown source of plasma of a very high density, or that the Tunguska object was not
a comet, but a cosmic object the composition and structure of which is unknown to astronomers and
physicists. This conclusion may affect the conceptual approach in devising protective systems for Earth
against asteroids and comets. Information regarding the geomagnetic storm of 30 June 1908 should be
made available to engineers developing nuclear missiles for destruction of comets.
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