Lake Cheko

Lake Cheko is a small bowl-shaped lake. It is about {{convert|500|m|ft}} long, {{convert|300|m|ft}} wide and {{convert|50|m|ft}} deep.{{cite journal | url=https://www.nature.com/news/2007/070627/full/news070625-8.html | title=Siberian lake could have been made by asteroid blast| journal=News@nature| date=27 June 2007 | accessdate=14 May 2018 | author=Chandler, David| doi=10.1038/news070625-8| s2cid=129158315| doi-access=free}}{{cite web | url=https://news.nationalgeographic.com/news/2007/11/071107-russia-crater.html | archive-url=https://web.archive.org/web/20071108211755/http://news.nationalgeographic.com/news/2007/11/071107-russia-crater.html | url-status=dead | archive-date=November 8, 2007 | title=Crater From 1908 Russian Space Impact Found, Team Says | publisher=National Geographic | date=November 7, 2007 | accessdate=14 May 2018 | author=Cristina Valsecchi, Maria}}

In the lake flows the Kimchu River (Russian: Кимчу), which flows into the Chunya River (Russian: Чуня), which in turn flows into the Podkamennaya Tunguska.{{cite web | url=http://198.74.48.154/bobk/tungmet.html | title=PRELIMINARY RESULTS FROM THE 1961 COMBINED TUNGUSKA METEORITE EXPEDITION | publisher=Meteoritica | date=May 1962 | accessdate=18 May 2018 | author=Florenskiy, K P}}{{Cite journal| title=On the Fall 'Of the Podkamennaya Tunguska Meteorite In 1908 | journal=Contributions of the Society for Research on Meteorites | volume=1 | pages=35–39 | author=Kulik, L.| doi=10.1111/j.1945-5100.1935.tb00263.x | year=1935 }}{{cite web | url=https://www.rbth.com/travel/2013/03/22/vanavara_discovering_siberian_mystery | title=Vanavara, discovering Siberian meteor mystery | publisher=Russia Beyond | date=January 20, 2014 | accessdate=18 May 2018}}

Lake Cheko is roughly {{convert|8|km|mi}} north-northwest{{cite web | url=http://tunguska.tsc.ru/f/4804/MainPart/newsletter.pdf | title=Cosmic Collision: The Lake Cheko — Tunguska 1908 Bolide Event | publisher=Science Newsletter | date=July 2007 | accessdate=19 May 2018 | author=Dockweiler, T.}} of the epicenter of the Tunguska event.{{Cite web |url=https://www.scientificamerican.com/article/the-tunguska-mystery-100-years-later/ |title=The Tunguska Mystery--100 Years Later |access-date=May 18, 2018}}The Tunguska Mystery--100 Years Later The lake is inside the blast zone,{{Cite web |url=https://www.researchgate.net/figure/Geological-map-of-the-area-Surrounding-Cheko-lake_fig3_267638609?_sg=aN8Yr7IDlOPIDQP9HSmAyShXirNf4RROQZ5bueAD_ekS65stdVRo9RK7YELvQ80d2cGVI1LQOW4x6tYmnys_Ig |title=The Tunguska event and Cheko lake origin: Dendrochronological analysis |author1=Fantucci, Rosanna |author2=Romano, Serra |author3=Kletetschka, Gunther |author4=Di Martino, Mario |website=researchgate.net |access-date=May 19, 2018}} and in the probable direction of whatever caused the Tunguska event.{{cite web | url=https://www.researchgate.net/figure/left-Landsat-image-of-the-Tunguska-area-with-indicated-the-pattern-of-trees-flattened_fig1_230602622 | title=Magnetic and seismic reflection study of Lake Cheko, a possible impact crater for the 1908 Tunguska Event | date=May 2012 | accessdate=19 May 2018 |author1=Gasperini, Luca |author2=Cocchi, Luca |author3=Stanghellini, Carlo |author4=Carmisciano, C. }}

A 1961 investigation estimated the age of the lake to be at least 5000 years, based on meters-thick silt deposits on the lake bed. However, Luca Gasperini and his co-investigators working in 2008 concluded that the sediments, isotopes, and pollen "suggest that Lake Cheko formed at the time of the Tunguska Event" and thus was only 100 years old.{{cite news|last=Rincon|first=Paul|title=Team makes Tunguska crater claim|url=http://news.bbc.co.uk/2/hi/science/nature/6239334.stm|accessdate=2013-02-15|newspaper=BBC News|date=2007-06-26}} They also reported that acoustic-echo soundings revealed a conical shape for the lake bed, which they interpreted as consistent with an impact crater. They said the lake's long axis points to the hypocenter of the Tunguska explosion, about 7.0 km away, and they interpreted magnetic readings as indicative of a possible meter-sized chunk of rock below the lake's deepest point, that they suggested could be a meteorite.

In 2008, a BBC News story on the 100th anniversary of the Tunguska Event mentioned that researchers at Imperial College London had pointed out that many of the trees surrounding the lake are older than 100 years, which suggests that the lake could not have been created by an impact in 1908. The researchers also pointed out other problems, including the morphology of the lake and the surrounding terrain, and the lack of impactor debris and ejecta, noting that the characteristics of the impactor required by the impact theory are inconsistent with existing models of the known features of the event. Other researchers have said it is unlikely that a stony meteorite in the right size range would have the mechanical strength necessary to survive atmospheric passage intact, and yet still retain a velocity large enough to excavate a crater that size on reaching the ground.

In 2017, Russian scientists reported isotope evidence showing the lake is older than the Tunguska Event.{{cite journal |last1=Rogozin |first1=D. Y. |last2=Darin |first2=A. V. |last3=Kalugin |first3=I. A. |last4=Melgunov |first4=M. S. |last5=Meydus |first5=A. V. |last6=Degermendzhi |first6=A. G. |title=Sedimentation rate in Cheko Lake (Evenkia, Siberia): New evidence on the problem of the 1908 Tunguska Event |journal=Doklady Earth Sciences |date=October 2017 |volume=476 |issue=2 |pages=1226–1228 |doi=10.1134/S1028334X17100269 |bibcode=2017DokES.476.1226R |s2cid=134128473 }}

• List of possible impact structures on Earth

{{reflist|refs=

{{cite journal

| last = Florenskiy

| first = K. P.

| authorlink = Kirill Florensky

| title = Preliminary results from the 1961 combined Tunguska meteorite expedition

| journal = Meteoritica

| volume = 23

| pages = 3–29

| year = 1963

| url = http://abob.libs.uga.edu/bobk/tungmet.html

| accessdate = 2007-06-26}}

{{cite journal

| last = Gasperini

| first = L.| title = Geophysical/sedimentological study of a lake close to the centre of the great 1908 Siberian (Tunguska) Explosion

| journal = NGF Abstracts and Proceedings

| issue = 1

| pages = 29–30

| year = 2001

| url = http://www-th.bo.infn.it/tunguska/GasperiniSvalbard.pdf

| accessdate = 2008-05-27 |display-authors=etal}}

{{cite journal

| last1 = Gasperini

| first1 = L.

| title = Reply - Lake Cheko and the Tunguska Event: impact or non-impact?

| journal = Terra Nova

| volume = 20

| issue = 2

| pages = 169–172

|date=April 2008

| doi = 10.1111/j.1365-3121.2008.00792.x

| last2 = Bonatti

| first2 = Enrico

| last3 = Longo

| first3 = Giuseppe |display-authors=etal| bibcode = 2008TeNov..20..169G

| doi-access = free

}}

{{cite journal

| last = Gasperini

| first = L.| title = The Tunguska Mystery

| journal = Scientific American

| volume = 298| issue = 6| pages = 80–86

|date=June 2008

|display-authors=etal| doi = 10.1038/scientificamerican0608-80| pmid = 18642546 | bibcode = 2008SciAm.298f..80G}}

{{cite web

| last = Rincon

| first = Paul

| title = Fire in the sky: Tunguska at 100

| work = BBC News

| url = http://news.bbc.co.uk/1/hi/sci/tech/7470283.stm

| accessdate = 2008-07-01 | date=2008-06-30}}

{{cite journal|last1=Collins

|first1 = G. S.

|last2=Artemieva

|first2=N.|author2-link=Natalia Artemieva

|last3=Wünnemann

|first3=K.

|last4=Bland

|first4=P. A.

|last5=Reimold

|first5=W. U.

|last6=Koeberl

|first6=C.

|title=Evidence that Lake Cheko is not an impact crater

|journal=Terra Nova

|volume=20

|issue=2

|pages=165–168

|doi=10.1111/j.1365-3121.2008.00791.x

|year = 2008

|display-authors=etal|bibcode=2008TeNov..20..165C

|doi-access=free

}}

}}

• [https://web.archive.org/web/20090110012714/http://www.geotimes.org/feb08/article.html?id=nn_crater.html geotimes.org site with 3D reconstruction of Lake Cheko]
• [https://www.researchgate.net/figure/Morphobathymetric-map-of-the-Lake-Cheko-obtained-by-Tunguska99-survey-data-over-an-aerial_fig3_230602622 Morphobathymetric map of the Lake Cheko]

Cheko

Category:Possible impact craters on Earth

Category:Tunguska event