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Beautiful and mysterious: but was Lake Cheko formed from the exploding Tunguska meteorite?

By The Siberian Times reporter
23 January 2017

Russian scientists deny theory of respected Italian team by 'proving' that the remote blue lake is older than the famous 1908.

Lake Cheko is located some 8 km from the supposed ground zero of the Tungiska Event. Picture: V. Romejko

The so-called Tunguska event, 109 years ago, remains an intriguing challenge for modern science and the subject of sharp disagreement among authorities. 

What is known is this: on 20 June 1908, a large fireball crossed the sky above the taiga over the Stony Tunguska River, and a mega explosion followed; it could be heard in villages 1,200 kilometres away, and its consequences on atmospheric pressure were detected in Britain. Some 2,000 square km (770 square miles) of forest was flattened, around 80 million trees, thousands of charred carcasses of reindeer were strewn on the ground. The explosion some 9 km above the surface was equivalent to 185 Hiroshima bombs, yet it was in one of Siberia's most remote areas and there were no reports of human fatalities. 

Tunguska event


Tunguska event

Some 2,000 square km (770 square miles) of forest was flattened, around 80 million trees. Pictures: The Siberian Times, Leonid Kulik

To witnesses, it appeared like Armageddon. One, 65 km away, was thrown from his chair by the heat blast. 'Suddenly...the sky was split in two, and high above the forest the whole northern part of the sky appeared covered with fire... at that moment there was a bang in the sky and a mighty crash. The crash was followed by a noise like stones falling from the sky, or of guns firing. The earth trembled.'

Another quote: 'I became so hot I couldn't bear it, as if my shirt was on fire. I wanted to tear off my shirt and throw it down, and then the sky slammed shut. A strong thump sounded and I was thrown a few yards.' Europe, in the days that followed, was treated to a sky show of silvery, glowing clouds, colourful sunsets and a strange nighttime luminescence. In England, it was light enough at midnight to play cricket and golf. Its impact was noticed by both the Smithsonian Astrophysical Observatory and the Mount Wilson Observatory, in the east and west of the USA, with the night sky glowing bright enough for people to read by its light.

Tunguska event


Tunguska event


Tunguska event

Traces of Tunguska event can be seen even now.  Pictures: The Siberian Times, Tunguska Page of Bologna University

It was reported early on as a meteorite falling to earth in Krasnoyarsk region, while foreign newspapers speculated on a volcanic eruption or even a UFO. No shortage of other explanations emerged:  a comet made of ice not rock that evaporated in the atmosphere; local Evanki people believed a visitation by the god Ogdy was responsible; some scientists claimed a black hole had collided with Earth; other sources asserted friendly aliens had shot down a meteorite that could have destroyed the planet.

It took decades - and only after the 1917 Bolshevik Revolution - for the area to be properly investigated, and expeditions led by Russian mineralogist Leonid Kulik led to a conundrum which still puzzles scientists: if it was a meteorite, where are the craters and the extraterrestrial matter?

Map


Italian team

Italian team registres the sediment cores on lake Cheko in 1999. Pictures: The Siberian Times, Tunguska Page of Bologna University

A decade ago, a research team from Italy's University of Bologna led by Luca Gasperini pointed to small bowl-shaped 500-metre diameter Lake Cheko as the impact crater. It is located some 8 km from the supposed ground zero of the Tungiska Event; it had not been marked on maps previously; seismic measurements of its bottom indicated that sediment had been building for around a century; and that the depth of the lake - which is shaped like a crater - was deeper than is typical for the region. They also concluded there is dense stony matter beneath the floor and sediment, the 'remnant' of the exploding meteorite. 

They reported that seismic reflection and magnetic data revealed an anomaly close to the lake's centre, less than 10 metres below the floor. This anomaly was compatible with the presence of a buried stony object and supports the notion Cheko is a an impact crater lake, they concluded.

Tunguska event

Landsat image of the Tunguska area with indicated the pattern of trees flattened after the 1908 explosion and the inferred epicenter. Yellow box indicates location of topographic маp (right). Picture: Luca Gasperini et al. 

The Italian team has also previously argued that flattened trees show that 'two bodies entered the atmosphere. One exploded about five miles (8km)  above ground, while the other hit the Earth where Lake Cheko is now'.

Russian scientists have now taken a closer look at Lake Cheko, and strongly dispute the Italian theory. They suggest the area was badly mapped and there is nothing surprising about Cheko not appearing on old maps. 

Researchers from Krasnoyarsk and Novosibirsk assessed the age by analysing the its bottom sediments, undertaking geochemical and biochemical analysis. 

Recently their colleagues from the Institute of Geology and Mineralogy, Siberian Branch of The Russian Academy of Sciences (RAS) completed radioscopic analysis of the core samples.

Lake Cheko

Morphobathymetric map of the Lake Cheko obtained by Tunguska99 survey data over an aerial photograph collected during TUNGUSKA99 expedition.  Picture: Luca Gasperini et al. 

The study indicates that the deepest sample they obtained is about 280 years old, which means that the lake is probably even older, because the researchers did not manage to obtain samples from the very bottom. So geologically the lake appears young: but not young enough to be a crater lake caused by Tunguska.

'Besides, there are other deep, practically round lakes in the Tunguska reserve, which look like Lake Cheko and probably have the same geological origin,' said a statement from the expedition centre of the Russian Geographical Society in the Siberian Federal District.

Full details of the Russian research are expected in scientific publications in July.

Lake Cheko


Russian team

Krasnoyarsk scientists take samples of the bottom sediments of lake Cheko in 2016. Pictures: RGO

An earlier 1961 investigation of the lake by Soviet scientists had dismissed a modern origin of Lake Cheko, arguing the presence of thick silt deposits in the lake's bed suggested an age of at least 5,000 years.

Other investigations have shown  small traces of silicate and magnetite in the soil in the Tunguska Event area. These were high in nickel.

The most likely theory appears to be that the celestial objects exploded and were destroyed in the atmosphere to the extent that only tiny particles of cosmic dust ended up on the surface. 

A 2013 study found rock samples of meteoric origin with traces of a carbon mineral called lonsdaleite, known to form when meteorites crash to Earth. But were these from the Tunguska event or unreleated meteor showers?

And another puzzle: if the Tunguska explosion did not cause this magical lake to form, what did? It does not appear to be ancient, perhaps only hundreds or thousands of years old. 

Comments (3)

Re: Gumi : Easyest way to get small piece of old tree trunk is walk to woods :-) just kidding,



But seriously: I dont understand theory about old/young lake - how they know that deposits are not from woods or marsh - it could be there before explosion, maybe like everywhere else in that area. Everybody know that Siberia is during summer marshy and wet - so everybody may be right - deposits are older, but lake is new.



Another point: I found page of simulated atomic blast on google map http://nuclearsecrecy.com/nukemap/ , you can try it yourself. Some scientist estimated , that power of explosion was 15MT, that means 1000xhiroshima bomb. I would believe even in much stronger power, because 55km far from ground zero -in Vanavara was man knocked down from chair- you need strong wind to do that. 30km from blast were evenks in tents lifted in the air, one of them kill thrown against tree - so there were fatalities, but "only" for natives - so nobody counted them.
Andrej, Slovakia
03/02/2017 14:26
1
0
Artist depicts Tunguska http://endaism.tumblr.com/post/149875125006/enda-odonoghue-tunguska-2016-oil-on-canvas
Hoover, Zurich
26/01/2017 16:29
0
1
Very good story!
Tell me please, how can i get a small piece of an old tree trunk. Thank you
Gumi, Austria
24/01/2017 19:33
2
1
1

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