When the sun began to rise on the morning of 13 August 1930 like any
other morning, little did the inhabitants along the banks of the River
Curuçá in the Brazilian Amazonas region, near the Peruvian
frontier, realise what was about to happen. The women of
the community had started washing clothing and the fishermen and
rubber-tappers had begun their days work. Suddenly, at about eight
o'clock, the sun became blood-red and a darkness fell over the region.
A large cloud of red dust filled the air, and then a fine white ash
descended to cover the trees and plants. There then followed
ear-piercing whistling sounds, three in total, after which three
mighty explosions were heard in rapid succession. Immediately after
the explosions, the whole forest became a blazing inferno which lasted
for several months, depopulating a large area. These terrifying events
caused the inhabitants to believe they were about to face death.
Five days later, Father Fedele d'Alviano, an Italian
Capuchin-Franciscan monk, began his annual missionary visit to the River
Curuçá area. He
came upon the people still in a highly agitated state, demanding of
him an explanation of what had happened. Trying to reassure them,
Fedele said that this was not the wrath of God coming upon them, but,
instead, the fall of a number of meteorites. Fedele interviewed many
hundreds of eye-witnesses of the event and sent his report to the
Informazioni Fides: L'Osservatore Romano, the Vatican newspaper
(1931). A report of the event was also published in the Daily Herald
newspaper (1931). In the Journal of the International Meteor
Organization, Vasilyev and Andreev (1989) make mention
of this event as a possible 'Brazilian twin' of 1908 Tunguska event.
In their note, Vasilyev and Andreev refer to a paper by Kulik (1931),
which contains information that was published in the Daily
Herald. Bailey et al. (1995) provide a summary of the
Daily Herald article and a complete translation of the
L'Osservatore Romano article.
In his article, Fedele states that he visited many sites along the
River Curuçá listening to what the inhabitants had to say. He
heard how that, as the whistling noises increased in intensity - like
those of artillery shells, the children ran to hide in the corners of
their huts. Some of the fishermen, however, gazed upwards and
witnessed large balls of fire falling from the sky. The three
explosions caused tremors like those of an earthquake and were heard
over distances of several hundreds of
kilometres. The Sun remained obscured by the rain of ash until
midday. The Daily Herald article refers to Fedele's report and also mentions that, when the 'meteors' struck
the ground, 'the whole forest was ablaze.' The fire is reported to
have lasted for some months, and depopulated a large region of the forest.
Bailey et al. make several comments on the L'Osservatore
Romano report, concluding that a fall apparently took place near
5° S and longitude
71.5° W. Bailey et al. point
out that the date of 13 August
coincides with the peak of the annual Perseid meteor shower. Since no
direction of travel, nor precise time of passage, of the fireballs is
given, the link with the Perseids cannot be confirmed. The appearance
of the dust before the passage of the fireballs is somewhat of a
mystery. Huyghe (1996) gives an excellent account of the events
surrounding the affair. Bailey et al. called for a search of
meteorological and seismological records covering the days and weeks
following the 13 August 1930. Lawrence Drake (1995),
Director of the San Calixto Observatory in La Paz, Bolivia, in a
letter to Mark Bailey, included the seismological record from La Paz
for 13 August 1930. The San Calixto Observatory, in operation since
1913, was one of the few places in the region which operated a
seismograph (de la Reza 2000a). In fact, one of the best seismological
registers of the day, using Galitzin photographic paper,
had been put into operation there in 1930 in time for the August
event. On this record, three events occurred, the first at 12:04:27,
the second at 12:04:51, and the third at 12:04:56 UT. These times
correspond to a few minutes after 8 o'clock in the morning local time
in the River Curuçá area. At the time, the events were,
however, assumed to have been
earthquakes at a distance of 210 km, which placed the location in Bolivia,
or possibly Peru, rather than in Brazil.
In the meantime, Ramiro de la Reza, an astrophysicist at the National
Observatory in Rio de Janeiro, noticed Bailey et al.'s paper and took
up the challenge. He organized a search for signs of an impact near
the location given by Bailey et al. On infrared images taken by the
LANDSAT satellite and from aeroplane radar maps, de la Reza identified
one major feature to the south-east of the town of Argemiro, near the
River Curuçá, which might be an impact signature. The feature
corresponds to an astrobleme about 1 km in diameter. De la Reza
led an expedition into the dense jungle along the banks of the
Curuçá to try to find evidence of an impact. The party
included the meteorite hunter Wilton de Carvalho and geologists Paolo
Martini and Arno Brichta. The expedition, also organized and financed
by Globo Television in Brazil, set out in June 1997 near the end of the rainy
season and was filmed by Richard Smith for the Quantum programme of
the ABC-TV, Australia (de la Reza 1998), which also provided partial
funding. Some "stones", i.e. compacted clay, were found in part of
wall and in the central structure at the location of the
suspected crater. However, no trace of crystallisation by impact was
found in these stones,
indicating that they were probably formed by
the upheaval of internal pressure-compacted layers. One very
interesting outcome of the expedition, was that de la Reza was able to
contact a possible eye-witness of the August 1930 event who stated
that only one
bolide was observed travelling from the north. This direction matches
very nicely the direction in which a Perseid meteor, originating from
periodic comet Swift-Tuttle, would have intercepted the Earth at
8:00am. However, one has to be cautious about how much reliance can be
placed on such a statement after the lapse of almost seventy years.
Regarding the detection of any iridium resulting from the impact,
de la Reza (2000b) believes that much more material would have
to be analysed in order to draw any firm conclusions. Also, it is uncertain
how much iridium is contained in hydrometeorites.
Roberto Gorelli, an Italian astronomer, has collected much
information about this event, and has estimated that the mass of the
meteorite was between 1000 and 25000 tons, with an energy of 100 Ktons,
making it the second largest meteoritical event in the twentieth
century after Tunguska (Gorelli 1995). Gorelli estimated a height of
disintegration of from 5 to 10 km for the body(ies). Angela Vega,
a seismologist at the San Calixto Observatory, at the
instigation of Ramiro de la Reza, carried out an in-depth study
of the La Paz record, and concluded that the signals could be the
result, not of an earthquake, but of surface waves of type Lg, that
is, Love waves crossing granite, indicative of a surface explosion or
meteorite impact (Vega 1996). Vega's reasons for the possible
acceptance of the record as a meteorite impact are: 1) the good
transmission of the seismic Lg waves, and 2) the low energy present in
the spectrum of amplitudes for periods less than 3.0 sec. Vega points out
that, assuming an impact in the River Curuçá area, 1300 km from
La Paz, the waves would have been less damped in their journey to
Bolivia because they travelled mostly parallel to the Andes mountain
range. The seismological station in Peru did not come into
commission until 1932, and for the station in Quito, Equador, the
waves would have had to cross the Andes in a transverse direction
and so suffer much damping. De la Reza (2000a) further points out that the
magnitudes of the events as recorded are consistent with those
expected from the conversion of the kinetic energy of meteorites into
seismological energy. However, Vega could not state categorically that
the waves were generated by a meteorite impact, only that it was one
possibility. The seismological record does, though, preclude an event
produced close to the La Paz station, and Vega's analysis of the
record is consistent also with only one surface event, or impact,
signature. Vega's paper is in Spanish, and
the author is indebted to Regina Aznar, a research student at the
Armagh Observatory, for providing a translation.
The structure investigated by de la Reza's expedition is of the correct
dimensions, but they could not explore the complete area of the crater
since one cannot see more than a few tens of metres in the now regrown
forest. A further, more intensive, aerial search
of the region could prove fruitful. The confirmation of this event
as a meteorite impact is of paramount
importance in helping to establish the rate at which small bodies in
the solar system collide with the Earth, and in assessing the amount
of environmental damage which is caused by such collisions.
Target South America
Incident at Curuçá by Patrick Huyghe, Sciences;Mar/Apr96, Vol. 36 Issue 2, p14
Brazilian Impact Craters - PDF format
Two "Tunguskas" in South America in the 1930's?
NEO Impact Hazard
Photograph and Reports of the Tunguska Afterglow
Bailey, M.E., D.J. Markham, S. Massai and J.E. Scriven. The 1930 August 13 "Brazilian Tunguska" Event, The Observatory, 115, p.250-253, 1995.
Daily Herald. Menace of meteors like huge bombs from space. 6 Mar 1931, p.9.
De la Reza, J. R. Rumble in the Jungle, Quantum programme of the ABC-TV, Australia, directed by Richard Smith, ABC-TV Science Unit, 1998.
De la Reza, J. R. Private communication to J. McFarland, 24 February 2000a.
De la Reza, J. R. Private communication to Dr. Serra, 21 March 2000b.
Drake, L. A. Private communication to M. E. Bailey, November 1995.
Gorelli, R. The Rio Curuçá Event. Meteorite!, August 1995, p.26.
Huyghe, P. Incident at Curuçá. The Sciences, p.14-17, March/April 1996.
Informazioni Fides, L'Osservatore Romano. The Fall of Three Bolides on the Amazonas. Strange and Frightening Phenomena. 1 March, p.5, 1931. (English translation in Bailey et al. 1995.)
Kulik, L.A. The Brazilian twin of the Tunguska meteorite. Priroda i Ljudi, 13-14, p.6, 1931.
Vasilyev, N. and G. Andreev. The Brazilian Twin of the Tunguska Meteorite: Myth or Reality? WGN, The Journal of the International Meteor Organization, 17, No.6, pp.247-248, 1989.
Vega, A. J. Posible Evidencia Sismica del Evento "Tunguska" del 13 de Agosto de 1930, Ocurrido en Brasil. Revista Geofisica Instituto Panamericano de Geografia e Historia 44, Enero-Junio, pp. 201-211, 1996.
Last Revised: 2009 November 10th