PLEASE NOTE:


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Date sent: Thu, 26 Jun 1997 15:58:36 -0400 (EDT)
From: Benny J Peiser <B.J.PEISER@livjm.ac.uk>
Subject: VICTOR CLUBE'S VIEWS ON IMPACT HAZARDS
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL

EVOLUTION, PUNCTUATIONAL CRISES AND THE THREAT TO CIVILISATION

Although Victor Clube's attached paper was published more than a year
ago, many list members might not have come across this reference.
Researchers interested in the topics of the Cambridge Conference
and Clube & Napier's 'giant comet' hypothesis will find a comprehensive
summary of Victor's current views on societal evolution,
neo-catastrophism and the controversy about impact rates and impact
hazards.

Benny J Peiser
----------------------------------------

SVM Clube: Evolution, Punctuational Crises and the Threat to
Civilisation. In: EARTH MOON AND PLANETS, 1996, Vol.72, No.1-3,
pp.433-440

The relationship between 'punctuated equilibrium' and 'impact crises'
is critically examined in the light of our present knowledge of
asteroids and comets. It turns out that the emphasis on relatively
narrow epochs associated with occasional 'NEO' impacts is probably
misplaced. Rather priority should be given to the wider and more
frequent epochs associated with multiple 'NEO' debris impacts which
result in so-called 'punctuational crises' afflicting the planets.
These comprise the global coolings, super-Tunguska events and generally
enhanced fireball flux produced by the larger orbital debris whenever
an active, dormant or dead comet fragments and produces a trail. Taken
as a whole and in conjunction with the target, the response function is
inevitably complex. Nevertheless we broadly expect that the strength of
a punctuational crisis will vary as the progenitor comet mass, the
inverse dispersion of its debris and the inverse delay since
fragmentation. The encounter of P/SL-9 with Jupiter may be taken as
representing an extreme punctuational crisis where the dispersion and
delay were exceptionally small. The more familiar crises affecting the
Earth with less extreme values of dispersion and delay, which have
resulted in civilization being disturbed a good many times during
recent millennia, are no less important however. Indeed, the next such
threat to civilization ostensibly has a roughly 1 in 4 lifetime chance.
Any support for the Spaceguard programme which detracts from
consideration of these punctuational crises, whatever their strength,
would seem now to be peculiarly wide of the mark.



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Date sent: Thu, 26 Jun 1997 15:36:01 -0400 (EDT)
From: Benny J Peiser <B.J.PEISER@livjm.ac.uk>
Subject: RISK MANAGEMENT AND NEO HAZARDS
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL

RISK MANAGEMENT APPLIED TO PLANETARY DEFENSE

G J Friedman: "Risk management applied to planetary defense". In:
IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS, 1997,
Vol.33, No.2 Pt2, pp.721-733

Increasing scientific evidence strongly supports the conclusion that
the major extinctions in the history of life on Earth were caused by
the impact of large near-Earth-orbit objects (NEOs) and that these
impacts will continue. Although the annual likelihood of this threat
from asteroids and comets is extremely low, the consequences are so
disastrous they have no precedent in human history. Alternatives to the
mitigation of this threat are vigorously debated and the author
suggests the application of risk management to develop a consensus for
the best strategy. An example of this methodology is applied to
planetary defense. The conclusion is that present NEO detection
programs should be intensified, NEOs should be characterized through
rendezvous missions and that intercept systems studies should be
undertaken. An education and public awareness initiative is also
recommended. A graduate engineering class at the University of Southern
California worked on this problem.



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Date sent: Thu, 26 Jun 1997 15:28:13 -0400 (EDT)
From: Benny J Peiser <B.J.PEISER@livjm.ac.uk>
Subject: GLOBAL EFFECTS OF THE THERA ERUPTION
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL

ARE VOLCANIC DISASTERS OVERRATED?

Acidity signals found in Greenland ice cores and corresponding narrow
tree rings have been linked to major climate catastrophes and social
upheavals before, during and after the Bronze Age. One of the most
thoroughly researched volcanic exlosions detected in both Greenland ice
cores and European tree rings occurred around 1628BC and is linked to
the eruption of Thera in the Aegean. This natural disaster is of
particular interest because it is associated with the collapse of the
Minoan civilisation on Crete (and to the Atlantis myth by many
scholars). Whilst the link between the actual eruption and the demise
of the Minoans is still highly controversial (despite the discovery of
a massive tsunamis layer and due to chronological problems), it is
unquestionable that the Thera event had a catastrophic effect on a
local and (tsunami related) regional level. But what are the ecological
and social effects of volcanic eruptions of similar magnitude on a
global level? This questions has now been raised by Dr Pyle of
Cambridge University. According to his calculations, similar eruptions
occur on a much more frequent scale but have much less global effects
as currently believed.

Benny J Peiser
----------------------------------------------------------------------

D M Pyle: "The global impact of the Minoan eruption of Santorini,
Greece." In: ENVIRONMENTAL GEOLOGY, 1997, Vol.30, No.1-2, pp.59-61

The Minoan eruption of Santorini was a large-magnitude natural event.
However, in terms of scale it ranks smaller in erupted volume and
eruptive intensity than the historical eruption of Tambora in 1815 AD,
and smaller in sulphur emission and, by inference, climatic effects
than both the Tambora and Mt. Pinatubo, 1991, eruptions. Eruption
statistics for the past 2000 years indicate that Minoan-size eruptions
typically occur at a rate of several per thousand years. Eruptions
resulting in a Minoan-scale injection of sulphur to the stratosphere
occur far more frequently - at a rate of one or two per century.
Inferences of massive sociological, religious and political impacts
from such eruptions owe more to mythology than reality.



CCCMENU CCC for 1997

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