The method of generation of self-oscillations in rocks is developed here. Self-oscillations arise as a result of direct and inverse mechanoelectric transformations without an external generator. Laboratory experiments were
executed with different samples. A relation between self-oscillation parameters from samples  humidity and direct electrical field applied to samples was detected

Kamshilin, A. N.

Kuzichkin, O. R.

Sokolnikov, M. A.

Volkova, E. N.

Earth-prints Repository

93
ANNALS  OF  GEOPHYSICS, VOL.  47, N.  1, February  2004
Mailing address: Dr. Anatoly N. Kamshilin, Schmidt
United Institute of Physics of the Earth, Russian Academy
of Sciences, ul. Bolshaya Gruzinskaya 10, D-242, GSP-5,
123995 Moscow, Russia; e-mail: kamshilin@ifz.ru
Key  words self-oscillations – mechanoelectric
self-oscillator – transformations – rocks
1. Introduction
It is known that a geological medium which
has large resources of energy is a complicated
multiphase system in which transformations and
interactions of geophysical fields of different ori-
gin proceed. There are experimentally detected
parametrical, resonance, non-linear properties of
rocks. A strong response to weak impacts was
observed (Nikolaev and Vereschagina, 1991; Ta-
rasov and Tarasova, 1995). The recently detected
activation of seismic regime in seismoactive
zones after powerful artificial electromagnetic
pulses and geomagnetic storms (Tarasov et al.,
1999; Tarasov and Tarasova, 2002) should be es-
pecially noticed.
The investigation of relations between geo-
physical fields and the investigation of proper-
ties of the lithosphere, as a converter of energy,
as well as the possibility to use this knowledge
in practice have aroused increasing interest.
This paper is dedicated to these problems.
2. Conditions of experiment
Figure 1 shows the skeleton diagram of a
usual laboratory device for the investigation of
mechanoelectric phenomena in rocks. The elec-
tric generator (1) is connected to the piezoelec-
tric transducer (2), which generates acoustic sig-
nal in the sample (3). The energy of the acoustic
oscillations is transformed in the sample into the
energy of the electric oscillations. Electrodes (4)
receive electric signals, which are amplified by
the amplifier (5) and directed to the recorder (6).
The authors designed the device, the skele-
ton diagram of which is shown in fig. 2. The
signal from the electrodes (3) is directed to the
special electronic unit (4). From the output of
the electronic unit the signal is directed to the
input of the piezoelectric transducer (1). 
The set-up of the components of the elec-
tronic unit allows for a positive feedback in a
closed circuit and provides the conditions of
stimulation of the self-oscillations. 
The self-oscillations arise because of the
mechanoelectric transformations in rock sam-
ples and the positive feedback and not because
of an external forcing oscillator. The authors
Self-oscillations in rocks,
results of laboratory experiments
Anatoly N. Kamshilin (1), Elena N. Volkova (1), Oleg R. Kuzichkin (2) and Mikhail A. Sokolnikov (2)
(1) Schmidt United Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia
(2) Muromsky Institute, Vladimir Region, Russia
Abstract
The method of generation of self-oscillations in rocks is developed here. Self-oscillations arise as a result of di-
rect and inverse mechanoelectric transformations without an external generator. Laboratory experiments were
executed with different samples. A relation between self-oscillation parameters from samples’ humidity and di-
rect electrical field applied to samples was detected.
94
Anatoly N. Kamshilin, Elena N. Volkova, Oleg R. Kuzichkin and Mikhail A. Sokolnikov 
Fig. 1. The skeleton diagram of the laboratory device
for the investigation of mechanoelectric phenomena in
rocks: 1 – electric generator; 2 – piezoelectric transduc-
er; 3 – sample; 4 – electrodes; 5 – amplifier; 6 – recorder.
Fig. 2. The skeleton diagram of the laboratory device
for the investigation of self-oscillations: 1 – piezoelec-
tric transducer; 2 – sample; 3 – electrodes; 4 –  elec-
tronic unit; 5 – recorder.
Fig. 3. The scheme of the self-oscillator (MSO) of the first type (S-E): 1 – sample (box with sand); 2 – meas-
uring transducer; 3 – emitting piezoelectric transducer; 4 – electronic unit; 5 – recording device; 6 – additional
electrodes; 7 – measuring electrodes; 8 – source of constant voltage.
95
Self-oscillations in rocks, results of laboratory experiments
have termed the device the Mechanoelectric
Self-Oscillator (MSO).
Various materials were used as samples in
the experiments: sand, clay, loam, concrete,
bricks. In this paper, some results of the exper-
iments with sand samples are presented. 
The sample was made in the form of a plas-
tic box (450 × 140 × 180 mm) filled with 19 kg
of sand. A piezoelectric transducer was located
on the sand surface. The resonant frequency of
the transducer was 30 kHz. The system of elec-
trodes was located inside the sample’s body.
Two types of mechanoelectric self-oscillators
were investigated. In the self-oscillator of the
first type (fig. 3) a transformation of acoustic
oscillations (S) into electric oscillations (E)
takes place. In the self-oscillator of the second
type (fig. 4) a transformation of electric oscilla-
tions into acoustic oscillations takes place. The
piezoelectric transducer (3) in the first device
functions as an emitter. Measuring electrodes
(7) are connected to the input of the electronic
unit (4). The signal from the measuring elec-
trodes is amplified by the electronic unit and is
then directed to the input of the piezoelectric
transducer. Additional electrodes (6) are con-
nected to the constant voltage source (8).
The recording device (5) records two sig-
nals: the signal UE ∗ K from the output of the
preamplifier of the electronic unit (4) and the
signal US from the output of the measuring
piezoelectric transducer (2). UE denotes a poten-
tial difference between the measuring electrodes
(7), K denotes the amplification factor of the
preamplifier. US corresponds to the displace-
ment of the sample surface in the relative units.
The analog-digital converter L-761 of the
«L-Card» Russian corporation (14 bits, signal
processor AD-2184, Analog Devices Inc.) was
utilized as the recording device.
Fig. 4. The scheme of the self-oscillator (MSO) of the second type (E-S): 1 – sample (box with sand); 2 –
measuring piezoelectric transducer; 3 – piezoelectric transducer-receiver; 4 – electronic unit; 5 – recording de-
vice; 6 – emitting electrodes.
96
Anatoly N. Kamshilin, Elena N. Volkova, Oleg R. Kuzichkin and Mikhail A. Sokolnikov 
Fig. 5a,b. MSO of the first type (E = 0): a) electric (UE) and acoustic (US) signals; b) spectra of the signals UE
and US.
The distinction between the first and the sec-
ond devices (fig. 4) is that the piezoelectric trans-
ducer functions as the receiver of acoustic sig-
nals. The electric output of the piezoelectric
transducer (3) is connected to the input of the
electronic unit (4). The output of the electronic
unit is connected to the emitting electrodes (6).
UE denotes the potential difference between the
emitting electrodes (6).
3. Results of the experiments
1)  The experimental results for the MSO
of the first type (fig. 3, transformation S-E) are
shown in figs. 5a,b, 6a,b, 7a,b and 8a,b. Elec-
tric and acoustic signals, generated in the sam-
ple during self-oscillations, are shown in figs.
5a, 6a, 7a and 8a. The corresponding spectra
are shown in figs. 5b, 6b, 7b and 8b.
Figures 5a,b and 6a,b illustrate the relation
between the parameters of self-oscillations and
the value of the external direct electric field E.
Figure 5a,b: E = 0, fig. 6a,b: E = 9 v/cm.
Change in the phase shift between the sig-
nals US and UE by almost 180° and change in
the self-oscillations frequency by 680 Hz is
caused by the influence of E. It is possible to
observe a small decrease of the oscillations
amplitude and the Q factor, comparing figs.
5b and 6b. 
Figures 7a,b and 8a,b show a relation be-
tween the parameters of self-oscillations and
the sample humidity. Figure 7a,b corresponds
to the room-dry sample; fig. 8a,b corresponds
to the sample, whose humidity is increased
by 3%. The phase shift between UE and US
is changed by several tens of degrees. The
frequency of self-oscillations is changed by
290 Hz. The amplitude of oscillations is de-
creased to half the value of the room dry
sample. 
2)  Results, obtained with the use of the
MSO of the second type (fig. 4, transforma-
tion E-S) are shown in fig. 9a-d.
A self-oscillations mode was generated in
the dry sample (fig. 9a). After that 100 ml of
water was poured onto the surface of the sam-
a b
97
Self-oscillations in rocks, results of laboratory experiments
Fig. 6a,b. MSO of the first type (E = 9 v/cm): a) electric (UE) and acoustic (US) signals; b) spectra of the sig-
nals UE and US.
Fig. 7a,b. MSO of the first type, dry sample: a) electric (UE) and acoustic (US) signals; b) spectra of the sig-
nals UE and US.
a b
a b
98
Anatoly N. Kamshilin, Elena N. Volkova, Oleg R. Kuzichkin and Mikhail A. Sokolnikov 
Fig. 9a. MSO of the second type. Change in self-
oscillations after sample damping. Measurements
were executed with 30-40 s intervals: dry sample,
electric (UE) and acoustic (US) signals.
Fig. 8a,b. MSO of the first type, sample’s humidity is increased by 3%: a) electric (UE) and acoustic (US) sig-
nals; b) spectra of the signals UE and US.
ple and three more measurements were taken
(fig. 9b-d). All measurements were executed
with 30-40 s intervals. 
Comparison of the presented oscillograms
traces the process disturbing the self-oscilla-
tions mode as a result of sample damping. Os-
cillations become unstable, and at the end of the
experiment, the amplitudes of oscillations in
both channels have decreased by approximate-
ly one order of magnitude.
4. Discussion
Only part of the obtained results are pre-
sented in the paper, other results are now being
processed. The presented material allows the
following conclusions.
1) Self-oscillations based on direct and in-
verse mechanoelectric transformations could be
created in rocks. The sample of rock is the fre-
quency defining element; frequency of self-os-
cillations, Q factor and amplitude are deter-
mined by the properties of the sample (object).
a b
bc
d
99
Self-oscillations in rocks, results of laboratory experiments
External influence (direct electric field) also
changes the parameters of self-oscillations.
This result is indirectly confirmed by a relation
between seismoelectric transformations and di-
rect electric field, as was detected earlier (Cher-
niak, 1987).
2) A change in condition of the sample
causes a change in phase shift between electric
and acoustic signals in the sample.
3) Preliminary results show that mechano-
electric self-oscillators of the first and second
type have different sensitivity to changes in
condition of the samples.
5. Conclusions
Investigation of the self-oscillation processes
in rocks in general, and processes based on mech-
anoelectric transformations in particular, are in-
teresting from the point of view of both funda-
mental and applied science. There are some pos-
sible directions:
1) Development of new methods of rock
investigation as mechanoelectrical transformer,
as well as development of methods of investi-
gation of different physical properties of rocks
(material composition, humidity, fluid quality,
porosity, anisotropy, etc.).
2) Development of a phenomenological
model of the mechanism of earthquake initia-
tion under impacts of different origin.
3) Natural modeling will open ways of
development of new methods of control con-
dition and purposeful influence on rocks and
other objects.
Acknowledgements
The authors are sincerely grateful to Prof.
S.D. Vinogradov, Dr. C. Anastasiadis, Dr. A.B.
Fig. 9b-d. MSO of the second type. Change in self-
oscillations after sample damping. Measurements
were executed with 30-40 s intervals: damped sam-
ple, electric (UE) and acoustic (US) signals.
100
Anatoly N. Kamshilin, Elena N. Volkova, Oleg R. Kuzichkin and Mikhail A. Sokolnikov 
Maksimov, and Mr. V.A. Terentjev for discus-
sion and for their valuable comments on the
essence of the work.
The investigation was executed with the
support of grant No. 304 of competition-expert-
ise No. 6 of young scientists of RAS.
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Self-oscillations in rocks,results of laboratory experiments

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