From: D.J.Hutt@newcastle.ac.uk (D.J. Hutt)
Newsgroups: sci.geo.geology
Subject: Re: Magnetic reversal?
Date: 17 Dec 92 11:58:04 GMT
Organization: University of Newcastle upon Tyne, UK NE1 7RU

>In article <51635@seismo.CSS.GOV> stead@skadi.CSS.GOV (Richard Stead) writes:
>>D.J.Hutt@newcastle.ac.uk (D.J. Hutt) writes:
>> >stead@skadi.CSS.GOV (Richard Stead) writes:
>> >The poles reverse frequently through geologic time.  But it never causes
>> >any big problems.
>> How do you know? Were you there to see the last one?
>
>That's a pretty ill-considered and stupid flame, and I take great offense at it,
>having worked in the field of paleomagnetism.  First of all - if no one alive
>today was alive for the "last one" how do we know the field ever reversed?
>By scienctific research, of course, same reason we know why the reversals do not
>cause big problems.
>
Sorry that this obviously caused offence, But I still stand by the general
gist of the comment - to say that it NEVER causes ANY big problems seems to
be a very sweeping statement especially as no-one really knows even now
HOW the reversal occurs. 
I recently attended a colloquium in our department on this very topic with 
the idea that the dipole actually turns along one of two lines (down through
the Americas, or down the Western Pacific) in which the effect is basially
a drift of the field away from the present pole. 
The other idea that the dipole actually decays to build up again seems to
be going out of favour.

>> If the field collapses the magnetosphere fails and we get bombarded by 
>> potential lethal cosmic rays. But this aside there are still many 
>
>Nope.  The 20% or so of the field that remains will still generate a
>powerful magnetosphere.  That's why studies of extinctions during
>reversals and excursions find only a few and only in polar regions.

A few extinctions at the polar regions occur - I didn't know that. Do you
still, therefore, maintain NO adverse effects? It can't be much fun for the
creatures that are extinguished!

So in summary there seems to be two types of problem/effect:-

a) Biological effects i.e.
   Navigation of Animals and Humans,
   Biomagnetic effects
   Extra high energy particles (cancer causing)

b) Technological effects i.e.
   Communications (radio transmission)
   Power transmission

Some of these have been dealt with before but I would like to consider a
possible scenario:

The Magnetic pole has moved to being situated over New York (during its 
migration down America). A solar storm occurs. The field is weakened during
its migration and the storm is fairly severe.
What happens? (look at aurora and present storms which occur at high 
latitudes away from most centres of population and the problems they cause) 
Power transmission throughout the city is wiped out as transformers trip
due to the induced current. Similarly the telephone system goes out of 
order. A few of the transformers (older ones) catch fire. 
Meanwhile the city is being bombarded with harmful radiation which may 
cause a few incidences of cancer, (in 20-30 years).

New Yorkers will not be happy!
While this is pure conjecture it does not seem entirely unreasonable.

No offence ever intended, just a different point of view!

Duncan.
Xref: sparky sci.geo.geology:2587 ca.earthquakes:1462