PLEASE NOTE:
*
CCNet 20/2003 - 21 February 2003
---------------------------------
"... These experiments indeed proved that the wave
run-up obtained
by extrapolation of what is obtained in tsunami waves cannot give
a
reliable estimate of the effect of explosion waves. As most of
the
energy is dissipated before the waves reach the shoreline, it is
evident that no catastrophe of damage by flooding can result from
explosion
waves as was initially feared. These experiments proved that wave
run-up due to explosion waves is much smaller as compared to
relative
run-up of tsunami waves."
--Van Dorn, 1968
(1) WARDING OFF ALL DOUBTS: NASA CLAIM TO HAVE "SOLVED"
1953 LUNAR FLASH
CONTROVERSY
NASANews@hq.nasa.gov
(2) 'DOUBLE WHAMMY' THAT CREATED THE MOON AND HAMMERED THE EARTH
BBC News Online, 19 February 2003
(3) HEAT IN THE HEART OF SPACE
The Oregonian, 21 February 2003
(4) 'SHOCKING' DISCOVERY BOOSTS CHANCE OF LIFE ON EUROPA
New Scientist, 21 Fenruary 2003
(5) MODELING WAVES
Science Central News, 20 February 2003
(6) VAN DORN REPORT
Jay Melosh <jmelosh@hindmost.lpl.arizona.edu>
(7) MEGA TUSNAMI: POSSIBLE LAYER LEFT BY THEM
Maximiliano Rocca <maxrocca@hotmail.com>
(8) RE: THE GREAT IMPACT DEABTE, PART II
Andy Smith <astrosafe22000@yahoo.com>
(9) WORLD REACTION TO EXTINCTION ASTEROID
Nick Sault <nsault@jadeworld.com>
===========
(1) WARDING OFF ALL DOUBTS: NASA CLAIM TO HAVE "SOLVED"
1953 LUNAR FLASH
CONTROVERSY
>From NASANews@hq.nasa.gov
Don Savage
Headquarters,
Washington
February 20, 2003
(Phone: 202/358-1727)
DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/393-9011)
RELEASE: 03-077
NASA SOLVES HALF-CENTURY OLD MOON MYSTERY
In the early morning hours of Nov. 15, 1953, an amateur
astronomer in
Oklahoma photographed what he believed to be a massive, white-hot
fireball
of vaporized rock rising from the center of the moon's face. If
his theory
was right, Dr. Leon Stuart would be the first and only human in
history to
witness and document the impact of an asteroid-sized body
impacting the
moon's scarred exterior.
Almost a half-century, numerous space probes and six manned lunar
landings
later, what had become known in astronomy circles, as
"Stuart's Event" was
still an unproven, controversial theory. Skeptics dismissed
Stuart's data as
inconclusive and claimed the flash was a result of a meteorite
entering
Earth's atmosphere. That is, until Dr. Bonnie J. Buratti, a
scientist at
NASA's Jet Propulsion Laboratory (JPL) in Pasadena, and Lane
Johnson of
Pomona College, Claremont, Calif., took a fresh look at the
50-year-old
lunar mystery.
"Stuart's remarkable photograph of the collision gave us an
excellent
starting point in our search," said Buratti. "We were
able to estimate the
energy produced by the collision. But we calculated that any
crater
resulting from the collision would have been too small to be seen
by even
the best Earth-based telescopes, so we looked elsewhere for
proof."
Buratti and Lane's reconnaissance of the 35-kilometer
(21.75-mile) wide
region where the impact likely occurred led them to observations
made by
spacecraft orbiting the moon. First, they dusted off photographs
taken from
the Lunar Orbiter spacecraft back in 1967, but none of the
craters appeared
a likely candidate. Then they consulted the more detailed imagery
taken from
the Clementine spacecraft in 1994.
"Using Stuart's photograph of the lunar flash, we estimated
the object that
hit the moon was approximately 20 meters (65.6 feet) across, and
the
resulting crater would be in the range of one to two kilometers
(.62 to 1.24
miles) across. We were looking for fresh craters with a
non-eroded
appearance," Buratti said.
Part of what makes a moon crater look "fresh" is the
appearance of a bluish
tinge to the surface. This bluish tinge indicates lunar soil that
is
relatively untouched by a process called "space
weathering," which reddens
the soil. Another indicator of a fresh crater is that it reflects
distinctly more light than the surrounding area.
Buratti and Lane's search of images from the Clementine mission
revealed a
1.5-kilometer (0.93 mile) wide crater. It had a bright blue,
fresh-appearing
layer of material surrounding the impact site, and it was located
in the
middle of Stuart's photograph of the 1953 flash. The crater's
size is
consistent with the energy produced by the observed flash; it has
the right
color and reflectance, and it is the right shape.
Having the vital statistics of Stuart's crater, Buratti and Lane
calculated
the energy released at impact was about .5 megatons (35 times
more powerful
than the Hiroshima atomic bomb). They estimate such events occur
on the
lunar surface once every half-century.
"To me this is the celestial equivalent of observing a
once-in-a-century
hurricane," observed Buratti. "We're taught the moon is
geologically dead,
but this proves that it is not. Here we can actually see weather
on the
moon," she said.
While Dr. Stuart passed on in 1968, his son Jerry Stuart offered
some
thoughts about Buratti and Lane's findings. "Astronomy is
all about
investigation and discovery. It was my father's passion, and I
know he would
be quite pleased," he said.
Buratti and Lane's study appears in the latest issue of the space
journal,
Icarus.
The NASA Planetary Geology and Planetary Astronomy Programs and
the National
Science Foundation funded Buratti's work. The California
Institute of
Technology manages JPL for NASA.
More information about NASA's planetary missions, astronomical
observations,
and laboratory measurements is available on the Internet at:
http://pds.jpl.nasa.gov
Information about NASA programs is available on the Internet at:
www.nasa.gov
MODERATOR'S NOTE: It is absolutely appropriate that NASA HQ stick
to the
findings of Bonnie Buratti, a JPL researcher, and Lane
Johnson of Pomona
College. After all, they have just published their 1953 lunar
impact theory
in the latest issue of Icarus. It is interesting to note,
nevertheless, that
all remaining doubts expressed from within the scientific
community in
recent weeks about the origins of the 1953 lunar flash have been
entirely
swept under the carpet in the latest NASA press release. As Jeff
Hecht
pointed out in a recent article in New Scientist (see CCNet 11
January 2003,
http://abob.libs.uga.edu/bobk/ccc/cc011003.html),
"if Buratti is right, such
impacts may be more frequent than thought - about once every 30
years on the
Earth, and every 500 years on the Moon." If Buratti and
Johnson are right,
it would also cast doubt over recent meteor and impact rate
estimates based
on 30 years worth of US military satellite data. Yet, despite my
own
lingering scepticism regarding the revised Tunguska-type impact
rate
estimates, I am not jumping at NASA's latest press release. Given
the rather
soft evidence provided by Buratti and Johnson (a debateable
photograph and a
tentatively 'recent' lunar impact crater), I think it is
premature for NASA
to claim that the 1953 lunar flash mystery has been
"solved" for good. Let's
not close the book on this theory as yet. Benny Peiser
===========
(2) 'DOUBLE WHAMMY' THAT CREATED THE MOON AND HAMMERED THE EARTH
>From The BBC News Online, 19 February 2003
http://news.bbc.co.uk/1/hi/sci/tech/2780399.stm
By Roland Pease
BBC Science
The Moon could have been created in a double-whammy impact, 4.5
billion
years ago, which virtually destroyed the Earth as it then
existed.
The theory, by US astrophysicist Dr Robin Canup, is outlined in
BBC Radio
4's "An Earth Made for Life" programme.
Like the climax in a firework display, the event was the
culmination of a
100-million-year process in which the Earth and its neighbouring
planets
were built through cosmic collisions between sub-planetary
objects. This was
the biggest blow our planet ever experienced.
According to Dr Canup, a proto-planet, something like the size of
Mars,
collided at high speed with an Earth that was nearly fully
formed.
The collision was a glancing one. It shattered our Earth, but
pulverised the
incoming planet.
Rain of debris
Simulations show the impactor being sprayed out into a shower of
orbiting
debris. But within a matter of hours, much of this had re-grouped
to form a
new impactor that smashed into the Earth's surface a second time.
"At this point, the impacting object was destroyed," Dr
Canup, of the
SouthWest Research Institute, in Boulder, Colorado, told the BBC.
Most of the impactor rained down onto and became incorporated
into the
Earth, the last major component to be integrated into our planet.
But 10% or so of the mass was spread out into an incandescent
disc around
the Earth - a scorching equivalent of Saturn's rings.
It was out of this material that the Moon was formed in a matter
of decades.
'Time zero'
"At the time it was 15 times closer than the Moon is
now," says Dr Canup.
"So if you had been able to stand on the surface of the
Earth then, you
would have seen something that appeared 15 times the size of what
even today
is an impressive full Moon."
Mike Drake of the Lunar and Planetary Institute calls the impact
"time zero"
for the Earth. Anything that had happened geologically to the
Earth before
that would have been erased by the impact.
The planet's surface was probably melted down to a depth of 1,000
kilometres, cloaking the Earth in a "magma" ocean that
would have radiated
like a red-hot furnace.
Tiny grains called "calcium-aluminium rich inclusions"
have been recovered
from comets, which are believed to be the oldest surviving solid
pieces of
the cloud of dust and gas that once encircled the forming Sun.
These have been dated to 4.566 billion years ago (give or take
just a couple
of million years) and are thought to represent the kind of stuff
that the
planets formed from.
The precise date the Moon was formed is still a matter of debate,
but Dr
Canup's research implies it was right at the end of the
planet-building
process, which could have taken up to 100 million years.
Curiously, recent chemical research has shown that the planet
Earth collided
with was a twin to the Earth - scientists have called it
"Theia" after the
mother of the Moon in Greek mythology.
Magma ocean
Details in the chemistry of the Moon show it to be almost
identical in some
key respects to the Earth, although it was made almost entirely
from
remnants of the impactor.
Cosmochemist Alex Halliday says that Theia must have been formed
in an orbit
almost identical to the Earth's. Time zero for Earth, it seems,
was the end
of time for its twin.
But it wasn't all destruction. As Robin Canup points out, the
Moon-forming
impact gave the Earth its spin on its axis that now gives us
24-hour days,
and stirs up the atmosphere so that no part of the Earth is too
hot or too
cold for life.
And the presence of the Moon gives the Earth a kind of
gravitational
counterbalance that stabilises its slightly inclined axis of
rotation - 23
degrees to its orbit - that gives us the congenial cycle of the
seasons over
a single orbit around the Sun.
And the scalding magma ocean, according to Mike Drake, was
(surprisingly)
the place where the water of the Earth's oceans would have been
held -
giving our planet one of its key ingredients for life.
Copyright 2003, BBC
===============
(3) HEAT IN THE HEART OF SPACE
>From The Oregonian, 21 February 2003
http://www.oregonlive.com/science/oregonian/index.ssf?/base/science/1045573592204000.xml
RICHARD L. HILL
An innovative spacecraft will soon give astronomers dazzling new
views of
the deepest reaches of the cosmos.
Called the Space Infrared Telescope Facility, or
"Sirtf" for short, the
1-ton spacecraft is scheduled for launch in mid-April aboard a
Delta rocket
from Cape Canaveral, Fla.
Scientists using the 13-foot-long telescope will be able to peer
through the
dense clouds of dust and gas that obscure many areas of the
universe,
gleaning information about how and when the first stars and
galaxies formed.
The $720 million observatory will detect longer-wavelength
infrared energy,
or heat, radiated by stars, planets, comets and other bodies.
Earth's
atmosphere blocks most of the infrared radiation that the
spacecraft's
sensitive detectors will be able to spot.
This is the fourth and final mission in NASA's Great
Observatories Program,
joining the Hubble Space Telescope, the Compton Gamma Ray
Observatory and
the Chandra X-Ray Observatory in scanning the universe across a
wide range
of the radiation wavelengths.
"This mission is the infrared cousin of the Hubble Space
Telescope," said
astronomer Michael Bicay, an official with the Sirtf Science
Center at the
California Institute of Technology. "It's going to provide a
similar kind of
capability, but at a wavelength that the Hubble cannot see."
Bicay said the new spacecraft will revolutionize scientific
thinking about
objects and processes ranging from the solar system's most remote
planets to
the edges of the universe.
"For example, I think this observatory will make major
contributions in the
area of planetary systems around other stars," he said.
"We know of more
than 100 planets around other stars, but we've never seen one --
their
presence is inferred by the gravitational effects that these
planets have on
their parent stars.
"What Sirtf will do is not only detect the star, but start
doing chemical
analyses that will characterize the planetary system around it.
We still
won't be able to image the planets directly because they are too
small, but
we can gain a more complete look at these planets."
With the spacecraft, scientists will be able to examine a variety
of
targets, including: The early universe, where most of the
radiation emitted
from stars and galaxies since the beginning of the universe have
shifted
into the infrared part of the spectrum. The distant planets of
Uranus,
Neptune and Pluto to detect temperature variations and chemical
compositions. Several of the solar system's moons, including
Saturn's
largest natural moon, Titan, and Neptune's largest moon, Triton.
The origins
and evolution of "ultraluminous" infrared galaxies,
which emit more
radiation at infrared wavelengths than in all other regions of
the
electromagnetic spectrum combined. Comets, asteroids and faint,
icy objects
in the Kuiper Belt found beyond Neptune's orbit.
Sirtf's instruments are too sensitive to examine such bright
objects as the
sun and Earth's moon.
Because its instruments are measuring infrared radiation, which
is primarily
heat, the spacecraft features innovations to keep it extremely
cold so that
it doesn't detect heat from itself.
The observatory will be placed in an Earth-trailing orbit around
the sun to
keep its instruments away from the heat-producing planet. The
spacecraft
will slowly drift away from Earth at the rate of about 10 million
miles each
year. In its frigid deep-space environment, the telescope mirror
and tube
will cool to about minus 396 degrees Fahrenheit.
One-half of the telescope's tube is painted black to radiate heat
into
space, while the side facing the sun is shaded by two flat solar
panels and
covered with a reflective coating.
To make the spacecraft's instruments even colder, they will be
bathed in
helium vapor from a tank that holds 95 gallons of liquid helium.
The feature
will keep the infrared instruments to about minus 449.5 F, a
scant 10
degrees above absolute zero -- the hypothetical point at which a
substance
would have no molecular motion, and therefore no heat.
Bicay said the amount of refrigerant determines the spacecraft's
life
expectancy. "There are three science instruments that draw
power, and each
needs to be cooled," he said. "If we use each of them
for a week at a time
-- switching them around constantly -- we think a five- or
six-year mission
is doable."
The 110-pound telescope, which has a 33.5-inch diameter aperture,
is made of
strong, lightweight beryllium.
The telescope mirrors will gather the infrared light for the
observatory's
three science instruments to image and analyze. They are: The
infrared array
camera, which provides imaging capabilities at near- and
mid-infrared
wavelengths. The general-purpose camera will be used for a wide
assortment
of astronomical observations. The camera's only moving part is
its shutter.
The infrared spectrograph that enables researchers to conduct
low- and
high-resolution spectroscopy at mid-infrared wavelengths.
Every element gives off specific electromagnetic radiation that
can be
identified. The instrument will enable astronomers to determine
which
elements are present in a distant star or galaxy and the
temperature and
chemical composition of planets within our solar system. The
multiband
imaging photometer that will provide imaging and some limited
spectroscopy
of far-infrared wavelengths.
Controllers will communicate with the observatory through NASA'S
Deep Space
Network, which has facilities at Goldstone in California's Mojave
Desert;
near Madrid, Spain; and near Canberra, Australia.
"About every 12 hours, we'll point the observatory's rear
end -- where the
antenna is located -- toward Earth and download the data that's
been
recorded during that time," Bicay said. The data will be
processed and
eventually placed in a public archive that astronomers can use.
About 100 astronomers have been selected for six teams that will
do initial
studies with the spacecraft after it's launched. Bicay said that
about 80
percent of the observing time then will be open to research
projects using a
rigorous peer-reviewed competition.
Gregory Bothun, an astronomer and professor of physics at the
University of
Oregon, said he will ask to use the observatory for research on
galaxy
evolution.
"It's going to potentially be a breakthrough for
astronomers," Bothun said,
"because it would unlock a lot of the mysteries that are
currently present.
But we're not going to know how well it works until it gets out
there.
"But I think this facility is going to be on the scale as
the Hubble Space
Telescope. It's going to be a very valuable addition in exploring
the
universe."
Copyright 2003, The Oregonian
===========
(4) 'SHOCKING' DISCOVERY BOOSTS CHANCE OF LIFE ON EUROPA
>From New Scientist, 21 Fenruary 2003
http://www.newscientist.com/news/news.jsp?id=ns99993421
Scientists simulating meteorite impacts on the frozen oceans of
Europa have
made an electrifying discovery, which raises the chances of
finding life on
Jupiter's moon.
Jerome Borucki, at the NASA Ames Research Center in California,
and his
colleagues fired aluminium bullets into a block of ice. They
found that when
the bullet impacted, sensors embedded in the ice detected an
electric shock.
A second, and much larger, electrical discharge was observed a
few moments
later.
A shell of ice many kilometres thick encases the surface of
Europa and
scientists speculate that liquid water - and therefore life -
might lie
beneath. Evidence for the presence of the molecular building
blocks for life
comes from the yellow-brown stains seen on the ice by the Galileo
probe.
"Europa is a high priority target for exploration because
the key
ingredients for life seem to be there. But even if you have the
ingredients,
the question is, is there a spark that creates the first organic
molecules?"
says Ron Greeley, a planetary scientist at the Arizona State
University.
Borucki's bullet experiments suggest meteorite impacts might have
provided
that spark. The electric shock had gone undetected because no-one
had put
sensors below an impact crater before, he told New Scientist. The
team think
the current is caused by the movement of protons as the ice
cracks.
Methane and ammonia
In the 1950s, Stanley Miller, now at the University of California
in San
Diego, showed that shooting an electric current through a mixture
of water,
methane and ammonia created complex organic molecules. Amino
acids, the
building blocks of proteins, were among the products.
Methane and ammonia are likely to be present in Europa's ice and
the energy
pumped into the ice by a meteorite impact will melt it. Shock
this mixture
with electricity, says Borucki, and complex molecules should
form.
But this still needs to be tested in the laboratory. So far the
experiments
have used only pure water ice, cooled to a chilly -196°C to
simulate
conditions on Europa.
The bullets used are about a centimetre across and were fired at
the ice at
a speed of six kilometres per second. This is the equivalent to a
kilometre-sized asteroid crashing into the moon at about 24 km/s.
"We do see a handful of very large craters on Europa, and
there would have
been a lot of energy associated with those," comments
Greeley. "These new
results are exciting."
Greeley has been appointed by NASA to set the scientific
priorities of
Jupiter's Icy Moon Orbiter. This probe, which has recently been
allocated
funding, will visit Europa and two of Jupiter's other moons,
Callista and
Ganymede. A lander may be sent to the surface of the Europa to
look for
organic matter. But it will be a long wait - Greenley estimates
the earliest
launch date for the mission to be 2011.
Journal reference: Journal of Geophysical Research - Planets (Vol
107, p 24)
Jenny Hogan
Copyright 2003, New Scientist
=========
(5) MODELING WAVES
>From Science Central News, 20 February 2003
http://www.sciencentral.com/news/articles/view.php3?language=english&type=article&article_id=218391890
It's a disaster that can kill thousands of people without
warning.
But as this ScienCentral News video reports, researchers studying
the
movement of water are now creating better ways to predict where
and how
tsunamis can affect us.
In movies like Paramount's "Deep Impact" and MGM's
"Meteor", a huge wave
caused by a comet or meteor crashing into the ocean wipes out
entire cities
and kills millions of people. But is such a wave possible?
In real life, a wave like that might be called a tsunami.
Tsunamis
(pronounced: "SOO-nah-MEEs") are usually caused by
earthquakes, explains
Stephan Grilli, a hydrodynamicist in the Department of Ocean
Engineering at
the University of Rhode Island. Grilli, who studies the movement
of water,
says, "Earthquakes shake the ocean bottom-move it up and
down-and that
produces waves on the surface. But earthquakes can also produce
underwater
landslides by shaking sediment-loosening up sediment.... Those
underwater
landslides can produce waves on the surface, and those waves, if
they occur
very close to shore, can be even more damaging" than waves
caused by
earthquakes.
The word "tsunami" is Japanese for "harbor
wave", because of the devastating
effects of these waves on low-lying Japanese coastal areas. But
because
tsunamis occur most often in earthquake-prone regions, many areas
other than
Japan are also at risk. For instance, tsunamis occur in the
Pacific Ocean,
along the coasts of Asia, Japan, and North and South America.
"These are
regions with very frequent earthquakes, and therefore very
frequent
tsunamis," says Grilli.
Not only are many areas at risk for tsunamis, but the waves occur
far more
frequently than one might think. "Many small tsunamis are
occurring on any
given day, but very few of those will be damaging," says
Grilli.
In order to forecast the effects of future tsunamis, Grilli
created a
computer program that predicts what a landslide-generated tsunami
would look
like in particular conditions. "The computer model actually
gives us numbers
that correspond to the motion, the speed, the elevation of a
tsunami,"
Grilli says.
Grilli says the computer model, which took many years to develop,
can be
used to study both past and future tsunamis. "A computer
model can help us
simulate tsunamis in many situations," he says. "So we
can actually
reproduce historical tsunamis, as well as [simulate] future
tsunamis that
could happen in an area where the potential for a landslide has
been
identified."
But how does Grilli know his computer model is accurate? He uses
real data
from two different sources: One is a wave tank, and the other is
history.
"The wave tank is like a large pool in which we can produce
all sorts of
waves," says Grilli. In fact, he created a scale model of a
landslide-a
device that he calls the "flying saucer"-that slides
down a slope in his
wave tank. That sliding motion produces waves on the surface that
look and
act just like a miniature tsunami. By measuring these small
tsunamis and
comparing those numbers to his computer data, he verifies the
predictions of
his computer model.
Grilli's use of historical accounts of tsunamis help verify his
computer
predictions-and at the same time help him investigate how they
occurred. For
example, he and some of his colleagues have studied a tragic
tsunami that
occurred in Papua New Guinea in 1998. In that event, about 15
minutes after
an average size earthquake occurred, very large waves hit the
country's
northern coast. It killed more than 2000 people, destroyed three
villages,
damaged 4 others, and left 12,000 people homeless. The waves were
much
bigger and they occurred later than what was expected for such an
earthquake. So what caused the tsunami? Researchers have been
searching for
the answer for many years.
Grilli says, "Looking at waves, we can tell by experience
where the source
was likely to be located, and it was about 40 miles
offshore." Additionally,
underwater sound recordings taken during that time revealed some
rumblings
that could have been caused by a landslide. So some of Grilli's
colleagues
created sonar images of the ocean bottom in that area and found
evidence of
a landslide. Using that data, soil samples, and his computer
model, Grilli
and his colleagues were able to piece together what happened.
Grilli says
the earthquake "produced a sizable landslide about 40 miles
off the coast,
and about 15 minutes later, very large waves reached the shore,
and those
were about 50 feet tall."
How did this help Grilli verify the accuracy of his model?
Grilli's
simulation of the tsunami matched the actual data-the size of the
wave, the
direction that it traveled, and the timing between the landslide
and the
waves hitting the coast-better than other computer models.
Grilli hopes that in the future he and others can use his
computer model to
help prevent such loss of life or the destruction of property
that occurs.
He has made his computer program available to the public via the
Internet so
others can use it to assess the risk from landslide-generated
tsunamis in
different areas. Grilli hopes the information can be used to warn
people,
and perhaps help prevent destruction from tsunamis. For example,
offshore
barriers could be built that could block or break up an incoming
tsunami
before it reaches shore; or underwater sensors could be used in
an advanced
warning system.
Grilli's research is funded by the National Science Foundation.
============================
* LETTERS TO THE MODERATOR *
============================
(6) VAN DORN REPORT
>From Jay Melosh <jmelosh@hindmost.lpl.arizona.edu>
Dear Benny:
You might be interested to post a paragraph from page 128 of Van
Dorn's 1968
report that epitomizes the message he was trying to send.
Reporter Rex
Dalton got a look at Van Dorn's personal copy and this paragraph
was marked
for emphasis, along with the handwritten addition (written in
1968!) "this goes for bolide impacts, too"!
The paragraph fragment follows a description of a series of
explosion
experiments performed in Mono Lake, CA in 1965 and 1966:
"... These experiments indeed proved that the wave
run-up obtained by
extrapolation of what is obtained in tsunami waves cannot give a
reliable
estimate of the effect of explosion waves. As most of the energy
is
dissipated before the waves reach the shoreline, it is evident
that no
catastrophe of damage by flooding can result from explosion waves
as was
initially feared. These experiments proved that wave run-up
due to
explosion waves is much smaller as compared to relative run-up of
tsunami
waves."
Sincerely, Jay Melosh
--
##############################################################
Jay
Melosh
Tel: (520) 621-2806
Professor of Planetary
Science
Fax: (520) 621-4933
Lunar and Planetary
Lab
email: jmelosh@lpl.arizona.edu
University of Arizona
Tucson AZ 85721-0092
===========
(7) MEGA TUSNAMI: POSSIBLE LAYER LEFT BY THEM
>From Maximiliano Rocca <maxrocca@hotmail.com>
Dear Benny:
I see the subject of Impact Mega Tsunamis is in nowadays CCNet.
It is a very
interesting subject.
I have something to share with the readers: a possible
sedimentary layer
left by a mega tsunami here in Argentina. I am still working on
the matter.
Thanks: max
Is the Interensenadense an impact mega tsunami deposit?
M.C.L.Rocca-Mendoza 2779-16A,Ciudad de Buenos Aires, Argentina
(1428DKU),
maxrocca@hotmail.com
This work was funded by The Planetary Society, CA, USA.
Introduction: Half a million years ago there was a major impact
event in
Argentina. Strong evidence of it comes from the studies of a
glass layer
enclosed in the mid Pleistocene age loessoid deposits of the
argentinian
pampas. There is also supporting evidence that the impact took
place
underwater, in the continental shelf, [1,2]. Oceanic impacts
create giant
waves, the mega tsunamis, so probably there should be evidences
of such
event in the coastal sediments of Argentina, [3].
A potentially nice candidate is the sediment layer left by a
'short marine
ingression' called the interensenadense. This mid Pleistocene age
sediment
was deposited in discordance and enclosed inside the Ensenada
Formation of
brown loess. Composed of brown-green sandy clay and carbonate
conglomerates
its thickness varies from 5 cm. up to 2 meters. Nice examples are
available
in the subsoil of Buenos Aires and La Plata cities, and in the
Atlantic
coast's outcrops of Buenos Aires province. The layer contains
fossil remains
of marine organisms and a mixed fauna of marine and fresh water
microfossils, [4,5].So far, this layer has been interpreted as a
'short,
sudden marine ingression'. However, some evidence supports a
close relation
with the impact. There is a report concerning the existence of
glassy
impactites ('escorias' ) enclosed 'in situ' in this layer at
Necochea, in
the Atlantic coast, [6]. The subject demands a review.
References:
[1] Schultz P.H., Zarate M. and Hames W.E. ( 2000 ) MAPS, 35(5),
supplement,
pp.A143-144.
[2] Bland P.A. et al. ( 2002 ): Science, 296, pp.1109-1111.
[3] Ward S.N. and Asphaug E. ( 2000 ) Icarus, 145, pp. 64-78.
[4] Frenguelli J. ( 1937 ) Notas Museo de la Plata , Geología,
2(4),
pp.111-123,(in Spanish).
[5] Frenguelli J. ( 1932 ) GAEA, 4 ( 1 ), pp. 29-39, ( in Spanish
).
[6] Ameghino F. (1934) "Obras completas y Correspondencia
Científica", Vol.
18, page 103 (in Spanish).
=========
(8) RE: THE GREAT IMPACT DEABTE, PART II
>From Andy Smith <astrosafe22000@yahoo.com>
Hi Benny and CCNet,
Part 2, of the debate, was very good and thought-provoking
and..thanks to
the CCNet....we can comment.
The Media
We have been very impressed with the media coverage of our
decade-old global
"wake-up call" to the dangers and the possibilities for
impact prevention
and survival. There have been lots of excellent features in print
and on the
video, internet and radio. Also, many outstanding books and
reports have
been written and they have raised the level of public awareness,
in a very
positive way. Even the movies have helped people to understand
the problem.
At this stage, we would give the media an "A" and this
Debate is an
excellent example of good media.
In our view, there has been very little hype and a lot of good
emergency
preparedness information transmission, which has helped us to get
modest funding increases, more
legislative support, etc. It has also helped tremendously, when
talking to
the public about planetary defense. In the early 90's very few
people knew
anything about the danger and the possibilities for defense. Now,
the
situation is much better.
Recorded History
We think Don Yeomans fumbled the ball, when he stated that
"scientists can
point to no person in recorded history who has been killed by an
asteroid or
comet". Our first thought was of Tunguska and Benny cited
Qingyang (1490
AD).
Reasonable Human Time Scale
Also we disagree with Joe Veverka's statement that
"asteroids and comets are
largely irrelevant to life on earth on any reasonable time
scale". We
routinely design and insure structures to withstand hundred-year
events and,
in some cases (nuclear reactors), to withstand thousand-year
events...and
the next Tunguska (or greater) impact is on that scale. The
danger is
real and the risks are alarming (in the light of the
consequences)...and
hundreds of experts, around the world, are working to prevent
impact, if
possible, and to survive impact, if we must. The Russians,
because of their
experiences, within the last century, take this threat very
seriously...and
so do many, many of us.
We also note that recorded history includes events that pre-date
the
invention of writing and that, as a result, we have reasonably
accurate
records of at least the last ten thousand years....to include
such major
events as the "great flood".
Part 3 (Nagging Little Problems)
We are looking forward to the next episode of this interesting
debate and we
hope that the points will be made that: (1) Most of the threat
population
(90%+)is in this category, (2) We cannot find most of these
objects with the
existing asteroid telescopes, (3)There are many very promising
third-generation systems in development and (4)The smallest of
these little
problems has the destructive power of a 20 megaton bomb and could
destroy
any metropolitan area on the planet.
Thanks again, to you all and to Space.Com, for producing this
great feature
and we encourage everyone to support the AIAA/Aerospace Planetary
Defense
Conference in California in early 2004. We are also working to
assist in the
organizing of a related conference in Houston in 2004. We're
making
progress.
Three Cheers.
Andy Smith/International Planetary Protection Alliance
astrosafe22000@yahoo.com
===========
(9) WORLD REACTION TO EXTINCTION ASTEROID
>From Nick Sault <nsault@jadeworld.com>
Hi Benny
I have been following the threads on whether the world would or
would not go
into panic at the news of a coming extinction event. My feeling
is not so
much that panic is the question. Call me pessimistic, but I
believe that
anarchy would be the thing to worry about.
If the world had say two months warning, what would be the
attitude of all
the workers in the world? Most ordinary workers would not go to
work if they
didn't have to. With two months to live, the majority of the
working force
would no doubt just stop. All services would stop; food growing,
food
distribution, fuel distribution, refuse collection, police, army,
law, etc,
etc. The army, of course, would be mobilized to stop
looters, but why would
the ordinary soldier care? It's not like a normal
catastrophe that would
soon be over and everything would return to normal. The
policemen and the
soldiers are going to die, so why would they bother to stop the
looters?
Then what would happen when all services came to a standstill?
People would
help themselves. Many people would moralize about how wrong
that was, but
would be forced to join the throng of looters eventually. Many
people who
had few luxuries in their lives would seize the opportunity to go
get what
they never had. Heck, we have enough people willing to do this
without the
world coming to an end in a few months.
To deny this would happen, is to really bury one's head in the
sands of
useless optimism. We get looters anyway during catastrophes.
Normally the
army and police are armed to shoot them on sight. But with
armageddon
looming, who would bother?
And if the ordinary citizen thinks everyone would rally to help
each other,
take note of this true story from my own experience:
I worked and lived in Saudi Arabia in the 70s and 80s. The giant
ARAMCO had
a number of oil towns (still do) that are anything but Arabian in
nature -
Dhahran was an American mid-west town transposed to the Arabian
desert. We
had all kinds of luxuries that you normally wouldn't get in
Saudi, not the
least of which was a commissary that sold American and European
products,
including Pork and bacon, denied to all others except the
American military
bases. Sometime during my sojourn in Dhahran, I can't remember
the exact
date, the commissary in Ras Tanura (which was the refinery town)
burned to
the ground. The good Americans and Europeans who lived in that
town had no
food to buy, so the company laid on buses for them to bus down to
Dhahran to
shop in the commissary there.
Remember these are professional people on salaries way above what
they would
get in their native countries. These are people with yachts,
large houses
and ranches back home, and many who will retire with a million or
so bucks
saved. What happened next was unbelievable. The rich residents of
Dhahran,
hearing that their colleagues and buddies were on their way down
in buses,
went on a massive shopping spree and pretty much cleaned out the
Dhahran
commissary.
I wrote to one of the CCNet correspondents who believed that
people would
rally, and he was aghast at my opinion of humanity. Well, sorry,
for being a
realist, sorry for not burying my head.
I personally would be awfully peeved at not being told of
impending doom,
but realistically it would be totally impractical to let people
know.
Nick Sault
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