[Turtle]

Originally Posted by FrankM

No, I haven't read about moonquakes. The article cited the duration of the vibrations generated by a moonquake as compared to earthquakes. It does not appear the moon has a central magna core, which in the earth acts a bit like silly putty. I suggest one take a golf ball and replace the core with silly putty and then see how far you can wack it.

As mentioned in the prior posts, piezoelectric action is not the primary mechanism for generating electrical charge generation in rock under extreme pressure. Since this action was not understood more than 5 years ago, NASA hadn't developed instrumentation to detect surface charge changes caused by moonquakes or even for earthquakes. The NASA researcher, Friedemann Freund, has suggested a network of surface charge detectors be deployed to identify charges being generated in an earthquake prone area, California.

Traditional seismologists are still depending upon mechanical sensors to detect earthquake action even though they have never been able to determine an impending earthquake with any degree of certainty. As with any new concept, the old school will be reluctant to change, as many are ill prepared cope with radical (to them) electromagnetic technology used in detecting earthquake pre-cursors.

That golf ball idea might make a big seller at the prank shop Frank!
So I went back and re-read this link you gave:
http://www.scec.org/instanet/01news/...nov_freund.pdf

Because the positive holes turn any rock momentarily into a pure p-type semiconductor [King and Freund, 1984],
the charge carriers will propagate outward from their source volume. When they intersect the surface of the Earth, the
ground potential is expected to become highly positive [Freund and Liu, 2000].

In a sense the thread title is outdated then, correct? Because piezo-electric effect is peculiar to only certain minerals whereas the electric effect you describe may occur in any rock type?
What instrument is suitable to measure the currents near & in caves? I have lava tube caves in my area. Thanks for keeping in touch Frank.

[FrankM]

In a sense the thread title is outdated then, correct?

The thread title was valid when it was first started, the knowledge about p-hole activity came about while researching "earth conductivity" issues. P-hole activity can occur in rock that contains no quartz, but unless the rock is pure quartz P-hole activity could be present at the same time piezoelectric action occurs (wonder how one would measure that?).

What instrument is suitable to measure the currents near & in caves? I have lava tube caves in my area.

I have posed that question to some of my correspondents whether "field mills" would be suitable for detecting the differences in the electric potential at the surface over voids. They are the only device that I know of that senses the potential of an electric field without an interconnection. It is the instrument of choice for measuring the relative electric field intensity at the earth's surface and in the atmosphere. I was told by a Professor of Earth Sciences that the potentials in caves and mines had never been measured, so what instrument is suitable there is not known. I suspect a field mill or similar differential detector device would have to be used.

Anytime you run a wire from the surface into an underground cavity it will disrupt the natural field, thus battery operated devices would have to be used to measure and record information. As noted in my previous post, there are few reports on the subject of measuring potential differences over underground voids.

[Turtle]

Originally Posted by FrankM

I have posed that question to some of my correspondents whether "field mills" would be suitable for detecting the differences in the electric potential at the surface over voids.
Anytime you run a wire from the surface into an underground cavity it will disrupt the natural field, thus battery operated devices would have to be used to measure and record information. As noted in my previous post, there are few reports on the subject of measuring potential differences over underground voids.

I searched 'field mill' as I didn't know that device & I found plans for building one.
http://www.precisionstrobe.com/jc/fi...fieldmill.html
I have a small multimeter & I thought one lead grounded & the other as an
aerial? Just thinking out loud. I will look over the field mill plans & description in more detail. Thanks as always Frank.

[Racoon]

Originally Posted by Turtle

http://www.scec.org/instanet/01news/...nov_freund.pdf

Because piezo-electric effect is peculiar to only certain minerals whereas the electric effect you describe may occur in any rock type?
What instrument is suitable to measure the currents near & in caves?

Maybe true Turtle,

But with the link you provided, are you also perhaps suggesting a correlation of Lightening activity and Seismic activity?

Just Curious,
while Looking for the next trash can to scavange!

[Turtle]

Originally Posted by Turtle

I searched 'field mill' as I didn't know that device & I found plans for building one.
http://www.precisionstrobe.com/jc/fi...fieldmill.html
I have a small multimeter & I thought one lead grounded & the other as an
aerial? Just thinking out loud. I will look over the field mill plans & description in more detail. Thanks as always Frank.

I re-read the 'build-your-own' plans again & also some other links on 'field mills'. I found a commercial model with computer software for about $2000 US here:
http://www.boltek.com/efm100.htm
I have in mind to experiment with my multimeter grounded & swinging a piece of wire on the other lead. Will the needle deflect? Shall I read for change in voltage?(not likely) Current? Resistance?
Racoon, I gave Frank's link & the only thing I suggest is that he is onto something different here. I intend to look into it...some more.

[FrankM]

Originally Posted by turtle

I have in mind to experiment with my multimeter grounded & swinging a piece of wire on the other lead. Will the needle deflect?

I doubt it. Typical multimeters are low impedance devices and they will effectively short out the small differential presented by the atmospheric gradient. At sea level the earth-to-air atmospheric gradient is approximately 100 volts/meter and I would hesitate to state what the potentials source impedance would be.

Originally Posted by racoon

But with the link you provided, are you also perhaps suggesting a correlation of Lightening activity and Seismic activity?

Lightning has not been reliably identified but many other types of atmospheric phenomena have been observed.

A light or glow in the sky sometimes heralds a big earthquake. On 17 January 1995, for example, there were 23 reported sightings in Kobe, Japan, of a white, blue, or orange light extending some 200 meters in the air and spreading 1 to 8 kilometers across the ground. Hours later a 6.9-magnitude earthquake killed more than 5500 people. Sky watchers and geologists have documented similar lights before earthquakes elsewhere in Japan since the 1960s and in Canada in 1988.

http://www.spectrum.ieee.org/print/2367

Anytime you place a conductive material within an electric field the characteristics of that field will be altered. A kite (ala Ben Franklin) or a helium balloon could hoist a thin wire such that a greater potential would be present, but you would still need a very high impedance measuring device. Also, Ben didn't have powerlines to worry about. The beauty of the field mill is that, except for its presence, it doesn't interject a large disturbance into the electric field.

[Racoon]

Originally Posted by Turtle

Racoon, I gave Frank's link & the only thing I suggest is that he is onto something different here. I intend to look into it...some more.

Sorry for blurting guys, I should have read the thread a little more closely.

It goes back quite a ways...
Very cool Frank M!! and Very interesting indeed.

I am now subscribed to this thread and will check out those links again.
Thank you for turning the wheel in my little rat cage!

So much Science, so little time....
Racoon

[Turtle]

Originally Posted by FrankM

I doubt it. Typical multimeters are low impedance devices and they will effectively short out the small differential presented by the atmospheric gradient...
http://www.spectrum.ieee.org/print/2367

Anytime you place a conductive material within an electric field the characteristics of that field will be altered. A kite (ala Ben Franklin) or a helium balloon could hoist a thin wire such that a greater potential would be present, but you would still need a very high impedance measuring device. Also, Ben didn't have powerlines to worry about. The beauty of the field mill is that, except for its presence, it doesn't interject a large disturbance into the electric field.

Ok on the multimeter, I do have the skills to build the field mill described in the link, but I may not have the persaverence. The commercial models are well out of my range. I will continue to consider the options.
I am an experienced kiter, & open space is a more difficult proposition in the area of the caves than is power lines. Then there is the matter of having enough wind.
What circuitry will increase the impedence? I have enough electronics skill to build simple bread-board circuits & 'Shacks in the area.
Good stuff1
Turtle

[FrankM]

There have been many improvements in high impedance low current voltage measurement devices, but I have virtually no expertise in this area. FET and CMOS devices can provide exceptionally high input impedances but I cannot state what level of impedance is necessary to avoid large errors in measurement values when attempting to measure potentials at the earth-atmosphere interface.

First, we do not know what potential differences exist over underground voids as compared to a non-void area. Also, we do not know whether or not specific atmospheric conditions will effect the potentials at the surface over voids. All we have are the various published statements, "caves and mines are dangerous during thunderstorms". Does a void increase the potential difference? The article by the caver suggests that potentials over voids are different.

We know that golfers are ushered off of golf courses when there are nearby thunderstorms, as it is known earth-to-air potentials at the surface can approach breakdown levels and any object protruding above the surface can influence the breakdown level; the term "point discharge object" is relevant.

Here is another site that provides info on building a field mill.
http://freespace.virgin.net/paul.z/E...meter%20MK%202

This device provides a methodology for determining polarity, which would be important for the determination of earthquake induced surface charge levels. Earthquake induced charges provide a short term polarity reversal at the surface relative to the atmosphere.

[Turtle]

Originally Posted by FrankM

Here is another site that provides info on building a field mill.
http://freespace.virgin.net/paul.z/E...meter%20MK%202

This device provides a methodology for determining polarity, which would be important for the determination of earthquake induced surface charge levels. Earthquake induced charges provide a short term polarity reversal at the surface relative to the atmosphere.

Thanks again Frank. Besides the added polarity indication feature, this model looks sturdier.
I haven't yet found a description of the field mills use in the field as it were. How they capture the data with the home-builts for example. I noticed most the references have the field mill stationary, but I rather had in mind to move with it on a line taking periodic stationary measurements. While this adds complexity to the data by changing position over time, if you consistantly use that method then you can build up a library of similar readings to compare.
I have bookmarked several of the articles linked to on the new satellite use in mapping Infrared & other variations, & the rock squeezing experiments producing the migrating holes. Off to study then; adieu.