From: stead@skadi.CSS.GOV (Richard Stead)
Newsgroups: ca.earthquakes
Subject: Re: The VAN Method
Date: 20 Aug 92 19:35:34 GMT


In article <1992Aug20.151641.847@unocal.com>, stgprao@st.unocal.COM (Richard Ottolini) writes:
> In article <cf#n2g-.bverreau@netcom.com> bverreau@netcom.com (stargazer) writes:
> >VAN method after the three Greek scientists who developed it, Profs.
> >Varotsos, Alexopoulos, and Nomikos.
> 
> This method has been tried in the US in the 1970s by Prof Gene Simmons
> and Malcolm Johnson of the Western USGS.  They looked at magnetotellurics
> and magnetics somewhere along the San Andreas.  They did not see much,
> probably because it was a guiet period.
> 
> >Tazieff spends much of the book railing against the 'experts'.  An
> >example paragraph:
> >
> > "The explanation for this attitude [hostility to the theory] lies, I
> >  believe, in a feeling of frustration associated with the fact that
> >  Varotsos, Alexopoulos, and Nomikos are not geophysicists, much less
> >  seismologists, but two solid-state physicists (V and A) and an
> >  electronics engineer (N), and they are thus outsiders in terms of
> >
> >In my mind this is where the book loses a lot of its credibility.
> >Paranoia and conspiracy theories are a hallmark of fringe science.
> 
> Agreed.
> However, very few geophysicists in the US receive training in electrical
> methods anymore, so the authors are likely to be experts as anyone else.
> I don't think there is a single commercial electrical crew operating in the
> US anymore.  Eletrical and EM methods had some utility for sulfide exploration,
> Of three prominent schools I attended- MIT, Harvard, and
> Stanford- only Stanford had some training in electrical methods and that was
> These methods are rarely talked about at major geophysics conventions.

I agree with the original poster's comments on paranoia.  That kind of talk
always raises big doubts with me regarding the scientific validity of
whatever they are supposedly protecting or being censored regarding.

However, I have to disagree with the comments regarding the current state
of electromagnetic methods and geophysics.  You claim that "These methods
are rarely talked about at major geophysics conventions".  However, the most
important geophysics convention is the Fall AGU in San Francisco each year.
At last year's meeting 3 sessions were devoted to this topic.  Sure, other
topics get more attention, and the proportion of US scientists is probably
smaller in these sessions than in those on other topics, but it's not being
ignored, and that's certain.  It is probably used at least as often as
gravity or magnetics to locate faults.  Generally, it is just considered
another tool in the toolbox for geophysical field work, not sexy research.
There have been efforts to develop an airborn magneto-telluric system, which
could make the method much more popular again.  It is true that some of
the more prominent geophysics universities no longer teach these methods,
but there are still a lot of programs that do.

Regarding the original post again - another thing I have trouble with here
is the apparent lack of understanding of basic physics (these guys are
supposed to be physicists, right?)  For example, they claim that the
polarization of the impurities is a peizo-electric effect.

> >   of the dipoles, and when the pressure reaches a certain critical value,
> >   the dipoles will be able to pivot freely and align themselves parallel
> >   to the electric field.  This change in polarization will be accompanied
> >   by emission of a piezoelectric current, that is, a current associated
> >   with a mechanical stress.  This is inevitably a transient phenomenon,

Wrong.  First of all, I don't think there is any such term as "piezoelectric
current".  But more than that, piezoelectricity is a phenomenom of a pure
crystal.  Impure crystals may still display piezoelectricity but it is the
result of the crystal lattice, not the impurities.  Piezoelectricity
does involve a response to mechanical stress, but that doesn't mean that's
all that's required to define it.

> >  "Each of these stations consists of at least two sensors, one oriented
> >   north-south and the other east-west.  The principle of these sensors
> >   is very simple:  two electrodes buried in the ground several dozen,
> >   hundred, or even a thousand feet apart, connected by a conductive wire
> >   to a voltage amplifier and a chart recorder."

Nothing new here.  This is just part of a primitive telluric measurement setup.
Same thing that the oil companies used to use for oil exploration, except
they actually used a much more sophisticated and accurate technique
back then.  These VAN guys would do themselves a favor by reading a
standard first-year geophysics text and learn how tellurics has been
done in the past - they wouldn't have to re-invent the whole thing.

(That's right - tellurics was used for oil exploration.  Basically,
tellurics measures the path of the telluric currents.  These are currents
induced in the earth by powerful fields in space.  The paths of the
currents change if the structure changes, so fault traps, anticline
traps, etc. can be found for oil.  A similar method - the self-potential
method - is what has been extensively used for sulfide exploration.)

--
Richard Stead
Center for Seismic Studies
Arlington, VA
stead@seismo.css.gov