A recent question about interpreting seismograms:

A modern book that is used as a classroom textbook is:

"Modern Global Seismology", by Thorn Lay and Terry C. Wallace.
Academic Press; 1995; ISBN 0-12-732870-X.

It covers the whole range of seismology and solid earth geophysics.
There is math and formulas, but it is quite readable, with lots
of figures, without deciphering the math.


About magnetic leviation:

There was an article in PHYSICS TODAY last September about diamagnetism
(the magnetism of normally non-magnetic materials). THey use a hugh
magnet (that takes 20 000 amperes at several megawatts) to levitate
things like blobs of water and a live frog in a 20 Tesla specially shaped
field (a common Alnico magnet is about 1 Tesla).
Since levitation is in fact balancing gravity, and gravity is changing
from 50 to 300 microgals daily due to earth tides, continuous fine-tuning
of the field is necessary. The diamagnetism is due to the forces on electrons
in the material that when immersed in the intense magnetic field become
weak magnets of the order of 1 gauss. THey report that the 1 gauss frog
is quite confused but otherwise unharmed.


Regards,
Sean-Thomas

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