Asteroid Comet Impact Hazards - Florida International University
Asteroid Comet Impact Hazards - Florida International University
Asteroid Comet Impact Hazards - Florida International University
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
GEOMAGNETIC EFFECTS AS ONE ASPECT OF THE TUNGUSKA EVENT<br />
Tunguska Home<br />
Documents Index<br />
Paper delivered at the <strong>International</strong> Workshop Tunguska -'96 Bologna, Italy<br />
GEOMAGNETIC EFFECTS AS ONE ASPECT OF THE TUNGUSKA EVENT<br />
by Victor Zhuravlev<br />
Geomagnetic effects produced by the Tunguska Event had no features in common with known<br />
disturbances caused by meteors. However, the disturbances strongly resembled local magnetic storms<br />
that occur after man made thermonuclear explosions in stratosphere. The similarity between the<br />
geomagnetic effects of the Tunguska Event and of the thermonuclear explosions just mentioned were<br />
generally dismissed by the scientific community because of its seeming unliklihood. As a result, the<br />
geomagnetic effects, as part of the accumulated Tunguska data, were forgotten, although the data were<br />
very significant and informative. An understanding of the significance and essence of those geomagnetic<br />
effects could well influence conceptual schemes in providing protection for our planet against potential<br />
asteroid and comet impacts.<br />
Two phenomena in the history of the Tunguska research are of key importance: 1) The explosion of the<br />
cosmic object occurred in the air; and 2) Analysis of the geomagnetic effects of 30 June 1908 recorded<br />
by the Irkutsk Observatory. The first phenomenon is commonly known nowadays, but the second has<br />
been all but forgotten.<br />
In spring of 1959, G.F. Plekhanov and N.B. Vassiliev found a brief report in a German scientific journal<br />
of 1908 that professor Weber of Kiel <strong>University</strong> observed unusual regular periodical deviations of the<br />
compass needle [Astronomische Nachrichten, 1908]. This effect was repeated each evening from 27<br />
June through 30 June 1908 and lasted for 7 hours during each occurrence. After the Tunguska explosion<br />
this effect disappeared. This publication, in addition to information from later scientific journals about<br />
the geomagnetic effects of thermonuclear explosions, in 1958 prompted Plekhanov and Vassiliev to send<br />
inquiries to various observatories that were in operation in 1908. However, the magnetograms that were<br />
received in response to their inquiries revealed no anomalies.<br />
However, in February 1960 the above investigators received a reply from the Irkutsk Observatory<br />
geophysicist Kim G. Ivanov informing them that he had discovered two unusual magnetograms dated 30<br />
June 1908. Both almost certainly had recorded the Tunguska disturbance. Ivanov himself did not offer<br />
his own interpretation of the physical nature of this unusual, unexpected effect. The analysis by<br />
geophysicist Alexander F. Kovalevsky and other researchers from Siberia's university city of Tomsk led<br />
scholars there to conclude that the magnetic effects of the Tunguska explosion had nothing in common<br />
with disturbances usually caused by typical meteors bodies. The closest analogy of the recorded<br />
magnetic effects, strange for meteoritics, turned out to be regional geomagnetic storms. Such storms had<br />
http://www.galisteo.com/tunguska/docs/zhur_us.html (1 of 2)12/5/2005 4:31:14 PM
Change language