In 1880, Piere and Jacques Curie identified quartz as a piezoelectric material. It took awhile longer to
identify the mechanism that made it piezoelectric and now many materials other than quartz are
manufactured with this characteristic.
One of the characteristics of piezoelectric materials is that they do not create an electrical output until
there is a change in pressure. The characteristics of the output, polarity and shape, will depend upon
the rapidity of the pressure change and whether it is an increased or decreased pressure. Some
materials are naturally piezoelectric, which means that the polar axis within the crystal are aligned
in the same direction. Artificially created piezoelectric materials get that way by the application of
heat and an electric field to align the polar axes in the same direction. The polarity of the electric field
determines the orientation of the alignment. All forms of rock are fine combinations of crystalline
material, and at depth rocks are subject to high pressures and heat. Figure 3 of the following article
denotes possible polar axis orientations.
Piezo
For some time, earthquakes and piezoelectrics have been associated, and it is generally postulated the
effect was associated with quartz-bearing rock. Earthquake lights are often cited as evidence of the
piezoelectric output, but little is known on how the electric charge associated with an earthquake moves
in the earth and what determines its polarity.
The big 1960 Chilean and 1964 Alaska earthquakes produced observable effects in the ionosphere and
serious studies have been underway to identify the mechanism.
NASA
Charge Carriers
The primary focus of these articles is the "dormant charge" and piezoelectricity was not mentioned.
The articles suggest that rock subjected to extreme stress suddenly behaves as a semiconductor.
Tthe 1964 Alaska earthquake created a large positive charge above the earthquake area. If we
postulate that the subsurface rock crystals were aligned as in the Figure 3(a), of the Piezo.pdf article,
and the earthquake created a decrease in pressure (stretching), the electrical output would be as
that exhibited in Figure 3(c), positive toward the surface.
Is it reasonable to postulate that the "electrical output" of an earthquake could be dependent upon
whether or not it occurred in an area (depth) where the polar axes are strongly aligned, and of course,
the magnitude of the pressure change. How far the generated charge propagates before it goes to zero is
another issue.
Links corrected, the "L" process inserted another http in front of the referenced http string and I didn't
see it.
