Nature of the tunguska impactor based on peat material from the explosion area

Abstract

The nature of the bright bolide and the giant explosion that took place on June 30, 1908, in the Podkamennaya Tunguska river basin, Central Siberia, is still being discussed. The area with fallen trees is in excess of 2000 square km (Fast et al. 1967), whereas the kinetic energy deposited by the impactor has been estimated to be ca. 15 million tons of TNT equivalent (or 1500 Hiroshima bombs; Vasiljev 1998). Nevertheless, Kolesnikov et al. (1973) have shown that the explosion could not be of nuclear nature. Its energy release was, in fact, too big to be a nuclear explosion. Two other nuclear hypotheses, one of annihilation and one of thermonuclear origin, have been tested by measuring 39Ar activity in rocks and soil at the explosion epicenter. No excess 39Ar was detected, and this method is much more sensitive than the method of measuring radiocarbon in tree rings (Cowan et al. 1965). Likewise no excess beta activity was observed in 1908, or the following years, in two ice cores from Camp Century nor in an ice core from DYE-3, all three on the Greenland ice sheet (Rasmussen et al. 1984). © 2007 Springer-Verlag Berlin Heidelberg.