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It is suggested that a black hole of substellar mass could explain many
of the mysteries associated with the Tunguska meteorite. This meteorite showed a
fiery trail accompanied by thermal radiation and a blast waste that levelled
forest over several hundred square km., but no crater or meteoritic material that
can unambiguously be associated with the event has ever been found. It has been
estimated that 10/sup 22/ to 10/sup 24/ ergs, equivalent to a 0.2 to 20 Mton
nuclear explosion, would be needed to cause such destruction. ln the proposed
explanation it is assumed that the black hole had the mass of a large asteroid
(10/sup 20/ to 1O/sup 22/ g). Although the geometric radius of such an object is
measured in Angstroms, its Newtonian gravitational field can be quite strong for
some distance. The velocity of the black hole is assumed to be slightly greater
than Earth escape velocity. Observational parameters for black; hole atmosphere
interaction are shown graphically. A shock wave is set up, and the rate of
energy deposition into the shock is calculated. If the black hole begins in
interstellar space with zero velocity and falls freely to the Earth's orbit it
would travel the last 30 km of the atmosphere in about 1 s and the total energy
in the blast wave would be 10/sup 22/ to 10/sup 24/ ergs for masses in the range
10/sup 20/ to 10/sup 22/ g. The black hole vvould leave no crater or material
residue, and the rigidity of the Earth rock would allow no underground shock wave.
Because of its high velocity, and since it loses only a small fraction of its
energy in passing through the Earth, the black hole should follow very nearly a
straight line through the Eanth. lts point of exit from the Earth could provide a
check for the hypothesis, since at the exit point there would be another air
shock wave, an underwater shock wave, and disturbance of the sea surface. (UK)
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