There is evidence that there were two massive bolide explosions which occurred over South America in the 1930's. One seems to have occurred over Amazonia, near the Brazil-Peru border, on August 13, 1930, whilst the other was over British Guyana on December 11, 1935. It is noted that these dates coincide with the peaks of the Perseids and the Geminids, although any association with those meteor showers is very tentative. The identification of such events is significant in particular in that they point to the need for re-assessment of the frequency of tunguska-type atmospheric detonations.

In 1989 an article by N.Vasilyev and G.V. Andreev in the IMO Journal (1) drew attention to a discussion, published in 1931 by L.A. Kulik (2), of a possible Brazilian counterpart to the Tunguska bolide explosion of 1908. The Brazilian event, which occurred on August 13, 1930, was described in the papal newspaper L'Osservatore Romano, the report being derived from Catholic missionaries working in Amazonia. That report, in Italian, was used as the basis of a front-page story in the London newspaper The Daily Herald (since closed down), which was published on March 6, 1931, and then seen by Kulik. (For the interested reader, a copy of the story is reprinted in the December 1995 Journal).

The locality of the explosion gives it it's name: The Rio Curaca event. This is close to the border between Brazil and Peru, at Latitude: 5 degrees South, Longitude: 71.5 degrees West.

Both of these newspaper stories were discussed in a recent paper by Bailey and co-workers (4), who provide an English translation of the story which appeared in L'Osservatore Romano. Since that paper should be accessible to many readers of WGN, I will not give an extensive account of it here. I will, however, just mention that although the eye-witness accounts give do cover the phenomena which one might expect to be produced by a massive bolide, there are some other interesting reported observation which would require some explanation. These include the following:
  • An ear-piercing "whistling" sound, which might be understood as being a manifestation of the electrophonic phenomena which have been discussed in WGN over the past few years.
  • The sun appearing to be "blood-red" before the explosion. I note that the event occurred at about 8h local time, so that the bolide probably came from the sunward side of the earth. If the object were spawning dust and meteoroids-- that is, it was cometary in nature--then, since low-inclination, eccentric orbits produce radiants close to the sun, it might be that the solar coloration (which, in this explanation, would have been witnessed elsewhere) was due to such dust in the line of sight to the sun. In short, the earth was within the tail of the small comet, if this explanation is correct.
  • There was a fall of fine ash prior to the explosion, which covered the surrounding vegetation with a blanket of white: I am at a loss with regard to this, if the observation is correct (and not mis-remembered as being prior-, rather than post-impact).
Bailey et al. also discuss the fact that the Rio Curaca event occurred on the day of the peak of the annual Perseid meteor shower, but conclude that this is likely to be purely a coincidence. The date is also close to August 10, on which day in 1972 a large bolide was filmed skipping through the upper atmosphere above western Wyoming and Montana, departing from the earth above Canada (4). Again, this may be merely a coincidence.

A brief discussion of the event is also given by R. Gorelli in august 1995 issue of Meteorite! magazine.