THE 1908 TUNGUSKA CATASTROPHE: A FORMING KIMBERLITE?
Wolfgang Kundt Bonn University, Germany
More than 17 reasons are presented of why the fiery Siberian event of 30 June 1908, near the Stony Tunguska river, was not caused by the infall of a stony asteroid, nor of an (icy) comet, but rather by the volcanic ejection of some 10 Mton of natural gas. For the volcanic (outflow) interpretation, estimates are presented of the involved mass and kinetic energy of the vented natural gas, of its outflow timescale, supersonic and subsonic ranges, and buoyant escape towards the exosphere. The Tunguska event may well have been the present-day formation of a kimberlite:
(1) The fact that in the literature, the comet-versus-asteroid debate is heftily alive rules against both interpretations: an asteroid would have left a trace, whereas a comet would have exploded too high, also would have been discovered weeks before impact.
(2) An impacting body, no matter of what consistency, cannot explain the many (> 12) conical holes in the ground, now lakes, which were formed on that morning. Nor can it explain
(3) the dozens of tree stumps lying around without recognizable origin, or
(4) the tree stump at the bottom of the drained Suslov hole.
(5) Why does the epicenter lie at the intersection of several fault lines, one of them running towards lake Baikal, and why does it coincide with the Kulikovskii crater, which belongs to the Khushminskii tectono-volcanic complex ? This constellation is reminiscent of kimberlites, as well as
(6) the local surface geometry, called 'amphi-theatre' by Kulik, with the 'Merrill circus' in the middle.
(7) The treefall pattern, which should be parallel for a low-inclination infall, is roughly radial. But it follows the valleys, shows islands of survival and islands of destruction, has
(8) more than 4 centers (Kulik's airphotographs) and has
(9) inverted profiles (Krinov), with undestroyed trees in the valleys, chopped-off tree-tops on the slopes, and felled trees near the hill tops, asking for blasts from below.
(10) The 'telegraph poles' near the epicenter require supersonic shock waves; they are reminiscent of the Hiroshima blast wave.
(11) Several eyewitnesses reported a large number of 'barisal guns' before they saw
(12) 'columns of fire'; this order of events, and orientation, are expected for a volcanic blowout, not for an impact.
(13) They sensed heat in their faces, which is difficult to realize for an impact trail.
(14) The 4 bright nights, straddling the explosive event, will be treated in my accompanying talk. They require clouds in the thermosphere, reminiscent of volcanic activity like Krakatoa (1883). Such volcanic blowouts have been recently detected in the form of
(15) rising 'mystery clouds' seen by airplane pilots, and in the form of
(16) 'pockmarks' on large parts of the ocean floor. (17) All chemical peculiarities found by expeditions were consistent with earthquakes, or 'degassings in active tectonic zones'. Remarkably,
(18) the 2000 Italian expedition recorded a radonic storm at gamma-rays near lake Cheko, which lasted some four hours.
(19) It is well known to geophysicists that only a small minority of terrestrial craters are of meteoritic origin; most of them were formed by volcanism. Volcanism has many different faces, ranging from hardly noticeable outgassing through lava flows through burning torches, mud volcanoes and real volcanoes all the way to explosive, supersonic ejections. In all cases, rising natural gas is the primary piston.