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

From: Dr. Svend Buhl <info_at_meteoritecentral.com>
Date: Sat Feb 4 09:35:16 2006
Message-ID: <002a01c62998$396adbb0$a2fdfea9_at_SVEND>

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 Curu?? 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 Curu?? 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
Curu?? 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 Curu?? 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 Curu??, 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 Curu?? 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 Curu??
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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Received on Sat 04 Feb 2006 09:35:19 AM PST