[meteorite-list] scientists still at odds on Tunguska Event

From: Greg Stanley <stanleygregr_at_meteoritecentral.com>
Date: Wed, 22 Jul 2009 12:49:09 -0700
Message-ID: <SNT117-W54D8382DCC00E4C143DD1AD21B0_at_phx.gbl>

http://en.rian.ru/analysis/20090722/155587125.html



____________________________________________________________
More than 100 years have passed since the Tunguska Meteorite
Event and the mystery of its occurrence remains unsolved, but
scientists have not given up on solving the riddle. This July, an
international research group from Italy and the United States ventured
into deepest Siberia to investigate the most likely explanations of the
mysterious event, and RIA Novosti correspondent David Burghardt joined
them.

On June 30, 1908, Eastern Siberia was hit by an
explosion equal to 2,000 times the nuclear bomb that destroyed the
Japanese city of Hiroshima in 1945, destroying 2,200 square kilometers
of taiga and flattening tens of millions of trees. If this impact had
occurred four hours later, the city of St. Petersburg and other nearby
villages would have been wiped off the face of the earth.
Travel to epicenter

Some 15 hours after the devastating impact, the skies throughout
Europe were lit up for several nights and white nights were noted in
places that had never experienced such a phenomenon. Witnesses at the
time in Britain, Denmark and Germany said they were able to read a
newspaper in the middle of the night without using any artificial light.


It
was not until the winter of 1927-1928 that the first expedition was
organized to investigate reports from witnesses of the event. The
expedition was led by Russian scientist Leonid Kulik, who headed for
the epicenter in search for the meteorite he believed was the only
possible explanation for the event. Travel back then to such a remote
area was a very expensive and grueling affair, taking first a train to
Krasnoyarsk in Eastern Siberia, and then traveling north on foot for
hundreds of kilometers. Kulik?s first expedition 19 years after the
event enlisted numerous native Evenki guides and dozens of reindeer.
Kulik, like hundreds of scientists after him, found no traces of a meteorite.
Travel to the area today is much easier than in Kulik?s time, taking
an airplane from Moscow to Krasnoyarsk, then a small prop plane to the
village of Vanavara, and finally a Russian Mi-8 cargo helicopter into
the region of the epicenter.

The two-week expedition included six professors from the University of Bologna, the University of Florence, and Cornell University.
There are some 100 theories of the Tunguska Event, including some of
the more bizarre ones of a UFO crash site, a WWII bomber caught in a
time warp and returning to 1908, Earth crossing through a black hole,
and a cloud of mosquitoes that spontaneously combusted due to heat
created by flying too densely.

The first theory was created in
1908 by native Evenki tribes in Eastern Siberia who were the actual
witnesses of the event. According to their legend, the fire god, Agdy,
became angered and destroyed all that was living in the area. Witnesses
said there were several deafening explosions and trees were heard
falling thousands of miles away.
Camp at Lake Cheko

The researchers looked at two of the most probable theories:
meteorite impact and volcanic gas vent explosion. The scientific
expedition was divided into two camps, one at Lake Cheko, where they
were researching the meteorite theory, and the other at Kulik?s Cabin
near the epicenter (some 10 kilometers from the first group), where
they were researching geological explanations for the blast.
 
METEORITE IMPACT THEORY (Lake Cheko)

Of the
hundreds of expeditions into the epicenter or impact area, not one has
found any evidence that a meteorite struck the Earth?s surface. Pieces
of a meteorite have never been discovered and no crater has been
confirmed anywhere in the area.

Four professors from the
University of Bologna, Carlo Stanghellini, Maurizio Serrazanetti,
Romano Serra, and Marco Cocchi, believe Lake Cheko was created by a
meteorite impact due to its shape and tree growth in the area. The lake
is elliptical (approximately 100 meters by 300 meters) rather than
round, which is consistent with other lakes and swamps in the area.
However, no impact ring or rim residue has been discovered at the lake,
which would be noticeable had a meteorite created the lake. The native
Evenki say that the lake has always been there and the name comes from
the Evenki language meaning ?dark waters.?

Professors
Stanghellini and Serrazanetti focused their research on the lake bottom
using both technical and not so technical equipment, including a
magnetometer, radar, underwater camera and grappling hooks.

The
scientists used a magnetometer to locate magnetic elements on the floor
of the lake such as iron or other metallic elements, which would
indicate that a meteorite or its fragments were on the bottom.
Stanghellini described a magnetometer as a sophisticated compass that
will show peaks on a monitor if it finds something metal. He said that
just like a regular compass, if you set a piece of metal near it, the
arrow will point to the metal piece and not to the magnetic North.
Because of the magnetometer?s sensitivity, the scientists did their
research on an inflatable rubber raft using wooden oars so as not spike
the instrument. Before the process, they flagged
the entire lake in 10-meter swaths. They discovered a small anomaly
in the center of the lake on one of the passes and said they would
study the data more thoroughly on their return to Italy. On the
following day, however, the magnetic anomaly was not detected on the
screen and the scientists did not collect any other substantial
evidence to support their theory that there are meteorite fragments on
the bottom of the lake.
 Lake Cheko research
They also conducted radar soundings and underwater filming, but again came up with no substantial evidence.

Grappling
hooks were dragged along the lake bottom to recover debris. They
recovered mostly small branches and roots, which may or may not have
been from 1908. The scientists said that the debris could have been
under a thick layer of silt that would have preserved the debris,
though they may have been recently deposited by the stream flowing into
the lake. These samples were packed and sent to the university to
define their age and find any proof of impact damage to them.
Stanghellini said further research of the lake?s bottom was
necessary, especially in drilling a core sample beneath the lake,
though this would require international support and financing.
On shore, professors Serra and Cocchi cut down several trees and
collected slabs as well as core samples of trees that survived the 1908
event, trees that were destroyed after the event and younger trees that
appeared after the event. Samples were taken on the North and South
side of Lake Cheko. According to their preliminary studies, the samples
showed that the trees had tight rings prior to the 1908 event, which
means the trees grew very slowly due to competition with other trees
and were growing densely together. Serra said that in 1908, the trees
show scars with resin deposits (pitch) and then a very slow growth rate
for two years due to shock. After 1910, the trees show much wider
rings, which indicate there was less competition with other trees, more
sunlight and nutrients. He also said that the coniferous trees in the
area should be associated with trees from the taiga and not lakeside
forests, where there is usually heavy underbrush. Serra said that tree
samples taken 4-50 meters from the lake are similar in growth patters
of trees 2-3 kilometers away from the lake prior to 1908, indicating
that all of the trees are native to a taiga environment and not a lake.
He added that a significant growth change occurred in the trees located
by the lake after 1908; whereas, those trees kilometers away from the
lake continued to have tight rings due to slow growth and competition.
Tree research at Lake Cheko
Serra noted that the survivor trees were much smaller during the
1908 event, meaning that they were bent over or twisted during the
impact. All of the large trees, on the other hand, were uprooted. He
said this is similar to what happens to trees during a hurricane. He
also noted that the tree samples taken near Lake Cheko were similar to
those taken after the Chernobyl nuclear reactor meltdown site in
Ukraine in 1986.

Evidence collected in previous expeditions by
Serra showed that tree limbs from 1908 contained deposits of magnesium,
titanium, sulfurs, and several undefined elements, which would support
the theories of a meteorite or even volcanic activity.

All
four of the Italian researchers at Lake Cheko believe the lake was
created by one of three impacts in 1908: the first exploded in the
atmosphere, the second struck the ground, creating Lake Cheko and
changing the direction of the creek, and the third struck the ground
further North at the epicenter, presumably creating several deep bogs.
They agreed that the meteorite that created the lake would have been
1-5 meters in diameter and the tree growth around the lake proved that
it was created in 1908.

Cocchi did much research on an old creek
bed that the scientists assume was cut off or rerouted after the 1908
event. Difficulties in researching the creek bed arise due to the fact
that 20 centimeters under the surface there is permafrost that cannot
be dug up. Drilling the creek bed is also planned to get a core sample
in order to estimate when the creek changed its course and began
flowing into the lake after it was created by the meteorite, according
to the scientists.

VOLCANIC GAS VENT EXPLOSION THEORY (Tunguska Epicenter)

Jason
Phipps Morgan, a geophysicist from Cornell University, and Paola
Vanucchi, a geologist and geophysicist from the University of Florence,
believe that the 1908 event was the result of a gas vent explosion
created from the center of the earth. They did much investigation
around the epicenter, especially what is called John?s Rock, which is a
10-12 ton rock formation that is free-standing. According to Morgan,
this rock was actually ?burped up? when the gas vent exploded, pushing
the rock to the surface through a funnel. Morgan named the still
unconfirmed funnel after his colleague, Paola?s Funnel. He noted that
this rock is the only one of its kind in the area and is definitely of
volcanic nature. The scientists collected some 30 kilograms of rock
samples, especially quartz and quartzite, from and around John?s Rock,
in search of shocked quartz, which would indicate that there was
volcanic activity in the area.
Geology research at epicenter
Vanucchi said that some of the rock samples showed traces of being
shocked, or fractured, and further research on the samples would be
completed in both Italy and the United States. She also said that they
believe they have found the main vent of the volcanic gas explosion
very near to John?s Rock.

The researchers revealed that the
Russian geological mineral map they were supplied with was incorrect in
many places in regard to the elements found in the area, as well as to
the depth of some of the quartz deposits. Vanucchi said that they had
started updating the existing map, but further research would be needed
to perfect it.

The scientists were also interested in Churgym
Waterfall which showed one of the largest samples of volcanic basalt in
the world, indicating millions of years of volcanic activity in the
area. There was a constant flow of lava, which is visible in layers
around the falls and stream. Only some 30 meters of the basalt is above
the surface, which is visible due to erosion by the stream and there is
no estimate of how deep the volcanic rock extends beneath the earth.

Morgan
said the amount of basalt in the area is so great that it proves the
existence of constant volcanic activity for millions of years. Samples
from the waterfall area were also taken for comparison with those from
the John?s Rock location. Though lava has ceased to reach the surface,
lava vents still exist and can build up pressure and blow, thus
creating a blast like that in the epicenter.

COMET THEORY

One
of the most commonly acceptable theories today is that of a comet or a
piece from the tail of a comet hitting the Earth?s surface. Upon
returning to Moscow, RIA Novosti spoke with two Russian scientists on
the comet theory.

Vitaly Romeiko, the director of the Department
of Astrophysics at Zvenigorod Observatory, said in an interview in
Moscow that the 1908 event was caused by a fragment of the Encke
Comet?s tail that entered the Earth?s atmosphere as a ball of ice with
small interplanetary fragments (dust particles) and, upon entrance,
exploded due to the negative ions in the comet and the positive ions
found on Earth. He pointed out that the Encke Comet also revolves
around the sun and comes near Earth every 3.3 years.

Romeiko has participated in 23 expeditions into the Tunguska region.

Olga
Gladysheva, a senior fellow at the A.F. Ioffe Physics and Technical
Institute in St. Petersburg, supported Romeiko?s theory in a separate
interview with RIA Novosti, adding that the part of the comet?s tail
separated and created a giant ice ball that was created in a vacuum,
and, therefore, made several explosions as the particles inside
expanded and the ball disintegrated.

The Russian scientists
base their theory on the fact on the absence of any meteorite material
in the area, no rock fragments, or no impact areas that would create a
crater.

Gladysheva said part of the comet?s tail entered the
Earth?s ionosphere at more than 80 kilometers above ground, which is an
intense area of atmospheric electricity. She said a major blast
occurred over the epicenter at an altitude of 7-10 kilometers above the
Earth?s surface. The significance of the blast was due to the overly
charged ions and differences in the positive and negative poles in the
comet and Earth.

Romeiko said the ice ball that formed around
the comet?s dust particles before striking Earth would explain the
absence of a crater or meteorite particles. The particles from the
comet would be very minute and could most likely be found in the lower
layers of peat moss in the area, which is frozen in permafrost.

101 YEARS OF AN UNSOLVED MYSTERY

In
separate conversations with the researchers during the expedition into
the Tunguska epicenter, they all shared the same idea that the mystery
will never be solved because scientists with their own theories and
hypotheses will never agree on one single explanation. In regard to
this, Romeiko said: ?No one will back down on a theory that he has
defended his entire life because that would mean failure.?

Although
the researchers returned without any substantial explanations for the
event, they plan on returning to Tunguska to continue their research
and prove their theories. Serra said there would be interest in the
Tunguska Event far into the future, because the best scientists from
around the world have been there and no one has come up with an
explanation, which scientists simply cannot accept.

When the
Italian and American research group left the epicenter, a new group of
Russian ?scientists? arrived. One of the group members said that she
had worked with a psychic to identify which swamp a UFO had collided
into in 1908.

Upon returning to the town of Vanavara, some 65
kilometers to the South of the epicenter, the Tunguska Reserve
director, Ludmila Logunova, said that they know where the meteorite is
located, but if they reveal its location, people would stop visiting
the region.

_________________________________________________________________
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Received on Wed 22 Jul 2009 03:49:09 PM PDT