[meteorite-list] 1930s Tunguska-Like Event?

[Dr. Svend Buhl]

Walter and list,

the incident Gallant refers to ocurred in the morning of the 13th August 
1930 in the area of the Curuca river near the Peruvian border. The report 
below is taken from John MC Farland's "The Day the Earth Trembled". If you 
need further information contact me off list, I can get you in contact with 
a Brasilian team which does some research on the incident.
"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 latitude 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 the perimeter 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."

Hope this helps

Best regards

Svend

www.niger-meteorite-recon.de

www.rollin-rock.com






----- Original Message ----- 
From: "Walter Branch" <branchw at bellsouth.net>
To: "Meteorite List" <meteorite-list at meteoritecentral.com>
Sent: Saturday, February 04, 2006 1:41 PM
Subject: [meteorite-list] 1930s Tunguska-Like Event?


> Hello Everyone,
>
> I have made up my mind that I am attending Tucson next year.  I am more 
> than a little jealous, reading all these wonderful reports and seeing the 
> photos.
>
> Relevant to my subject line, I have just settled down with Roy Gallent's 
> book, "Meteorite Hunter:  The Search for Siberian Meteorite Craters."  In 
> the forward, the writer (Nickolai V. Vasiliev) states. "In the 1930s a 
> similar event [to the Tunguska blast] occurred in the upper flows of the 
> Amazon River.  Again, due to it's remoteness the event is known only to a 
> small circle of specialists."
>
> I admit I have not read the rest of the book but does anyone know anything 
> about this supposed event?  Is anyone here a member of the circle of 
> specialists?
>
> -Walter Branch
> ________________________
>
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