Subject: Roberto Gorelli article on recent megaton class impacts
Date sent: Mon, 26 May 1997 23:31:03 -0500 (CDT)

I came across the following message from George Zay while perusing the
archives of the meteorite mailing list at Meteorite Central. Zay summarizes
an article by Roberto Gorelli which appeared in a recent issue of the
International Meteor Organization journal "WGN." I have not read the
original article myself. Mr. Gorelli presented a paper on this same topic
at last summer's Tunguska '96 conference. I do not believe the proceedings
of that conference are available yet. They are scheduled to appear in a
special issue of the journal "Planetary and Space Science."

-- Phil "Pib" Burns
Northwestern University, Evanston, IL. USA


I thought some of you might find this of some interest?
George Zay

Roberto Gorelli of Italy wrote a short article in the International Meteor
Organizations journal WGN about "Real Frequency of Meteoritical Events of
Megatonic Class".

Paraphrasing the articles conclusion, he calculated that the frequency of a
Megatonic impact somewhere over the earth is at every 10 years and the
frequency of such an event occuring over land would be about every 30-35
years...and this is believed to be an underestimation. He provided a list of
the known 7 megatonic impact events of the last two centuries. They are:

1. April 5, 1800. North America: Fall of a big meteorite with an earthquake
and destruction of a forest. Released Energy unknown. Source: E.Howard in
Transactions Philosoph. Ann; 1802, 23, Chapter 338.

2. November 9 or 19, 1819, Canada and Northern United States: Black rain
accompanied by bolids, shaking as of an earthquake, and obscuration of the
sky, Released energy unknown. Sources: (1) Zurcher, Meteors. p.238; (2)
Edinburgh Philosophical Journal 2-381; (3) F.G. Plummer in U.S. Forest
Service bulletin no. 117.

3. February 24, 1885, Pacific Ocean Long: 170 deg East, Lat: 37 deg North;
Red inflamed sky, blinding mass fell on the ocean and lifted a big mass of
water. Released energy unknown. Source report of Mr. Innerwish transmitted to
the Hydrographic Office in Washington by the San Francisco branch and
published in Science, 5-242.

4. May 3, 1892, Sweden, Norway, Denmark and surrounding locations: Fall of
500 tons of dust. Released energy unknown.

5. June 30, 1908, tunguska, Siberia, Russia; Released energy: 12.5 megatons.

6. August 13, 1930, Rio Curuca, Amazonia, Brazil: Released Energy: 0.1 - 1

7. December 11, 1935, West Marudi Mountain, British Guyana, Released Energy:
more than 10 megatons?


CCCMENU CCC for 1997

The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of

The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of Georgia or the University System of Georgia.