Megacryometeors: fall of atmospheric ice blocks from ancient to modern times
presented by
Jesus Martinez-Frias
Centro de Astrobiología (CSIC-INTA) Associated to the NASA Astrobiology Institute, Instituto Nacional de Técnica Aeroespacial Ctra de Torrejón a Ajalvir, km 4 28850 Torrejón de Ardoz, Madrid (Spain)
joint research with
David Travis (Department of Geography and Geology, University of Wisconsin-Whitewater, Whitewater WI, 53190, USA)
Although the term "Tunguska Event" normally refers to the tremendous cosmic explosion that was observed on June 30, 1908 in Central Siberia over the Krasnoyarsk Territory, Irkutsk Region, and Yakutiya, destroying about 2,150 square kilometre of Siberian taigà (1-5), some other alternative hypothesis have also been proposed, including, among others, a black hole (6), anti- and mirror- matter (7-9) and the coupling between tectonic and atmospheric processes (10,11). A much less violent but related threat is that of anomalously large hail and "clear air" ice blocks that have been reported striking the surface at an increasing rate during the past few years.
Since the unusual events of falls of large blocks of ice were first reported in Spain in 2000, additional occurrences have been identified in Spain as well as many others parts of the world (e.g. Italy, Austria, Argentina, Colombia, Canada and The Netherlands). A research program has been initiated in Spain (
http://tierra.rediris.es/bloquesdehielo) to accomplish the following: a) confirm the atmospheric nature of the ice blocks (12-14), with some of them of up to 18 kg in weight, b) to obtain an updated systematic database incorporating similar events around the world (15), c) to have the samples well preserved in freezer rooms for their study, d) to promote the creation of an international working group that can communicate through an electronic network, and e) to inform the public about the importance of reporting the occurrence of new falls.
The study of the textural, hydrochemical and isotopic characteristics of the ice blocks indicate that they mostly share the features which have been observed in large atmospheric hailstones, and that they were formed from water of variable mineralization. d18O and dD (V-SMOW) of the samples fall within the Craig's Meteoric Water Line. Isotopic mapping of dD values in the ice blocks display: 1) significant general variations from -24.4‰ to -126.4‰, and b) specific variations of up to 25 dD within some individual blocks. Some unusual atmospheric conditions have been observed to be occurring during the times of the falls including tropopause folding, ozone depression, and wind shear. Additional mechanisms (i.e. extra ionization, external perturbation of the system, injection of ion concentration from aircraft condensation trails) are also being considered as possible contributors to the initial formation of the first "ice nuclei". The term "megacryometeors" is proposed here as the name of these anomalous atmospheric blocks of ice.
References: (1) N. V. Vasilyev
http://www.galisteo.com/tunguska/docs/tmpt.html. (2) Whipple, F.J.W. (1930). The great Siberian meteor and the waves, seismic and aerial, which it produced. Royal Meteorological Society Quarterly Journal 56:287-304.
(3) Astapowitsch, I.S. (1934). Air waves caused by the fall of the meteorite on 30th June, 1908, in Central Siberia. Royal Meteorological Society Quarterly Journal 60:493-504.
(4) Chyba, Christopher F., Paul J. Thomas, and Kevin J. Zahnle (1993), The 1908 Tunguska Explosion: Atmospheric Disruption of a Stony Asteroid, Nature, 361, 40-44.
(5) Shuvalov, V.V. & Artemieva, N.A. (2002) Numerical modeling of Tunguska-like impacts. Planetary and Space Science 50, 181-192 (6) Jackson and Ryan, M. P. (1973) Was the Tunguska Event Due to a Black Hole?" Nature 245, 88-89.
(7) Crannel. J. (1975)Experiments to Measure the Anti-Matter Content of the Tunguska Meteorite." Nature 248, 396-398.
(8) Foot, R. (2001) The Mirror World Interpretation of the 1908 Tunguska Event and Other More Recent Events. Acta Physica Polonica B. Vol. 32, No. 10, 3133.
(9) Foot, R. & Yoon, T.L. (2002) Exotic meteoritic phenomena: The Tunguska event and anomalous low altitude fireballs -- manifestations of the mirror world? Astrophysics, abstract. astro-ph/0203152
http://arxiv.org/pdf/astro-ph/020315 (10) Ol'khovatov, A.Yu. (1991) O veroyatnoi roli seismotectonicheskikh protsessov v Tungusskom fenomene 1908 g. // Izvestiya AN SSSR, Fizika Zemli, N 7, p.105 (in Russ.).
(11) Ol'khovatov, A. Yu
http://www.geocities.com/CapeCanaveral/ ... nguska.htm (12) Martínez-Frías,J., López-Vera,J., García, N., Delgado, A., García, R. & Montero, P. (2000) Hailstones fall from clear Spain skies" Geotimes, 45-6, 5-6.
(13) Martínez-Frías, J., Millán, M., García, N., López-Vera, F., Delgado, A., García, R., Rodríguez-Losada, J.A., Reyes, E., Martín Rubí, J.A. & Gómez-Coedo, A. (2001) Compositional heterogeneity of hailstones: Atmospheric conditions and possible environmental implications AMBIO 30-7: 452-455.
(14) Santoyo, E., García, R. Martínez-Frías, J. López-Vera, F. & Verma, S. P. (2002) Capillary Electrophoretic Analysis of Inorganic Anions in Atmospheric Hailstone Samples. Journal Chromatography A (in press).
(15) Meaden, G.T. (1977). The giant ice meteor mystery. J. Met. 2, 137-141.
(16) Corliss, W.R. (1983). Ice falls or hydrometeors. In: Tornados, Dark Days, Anomalous Precipitation and Related Weather Phenomena. A Catalog of Geophysical Anomalies. The Sourcebook Project. P.O. Box 107, Glen Arm, MD 21057, pp. 40-44.
Date received: April 30, 2002