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| Titel |
Electromagnetic earthquake triggering phenomena: State-of-the-art research and future developments |
| VerfasserIn |
Vladimir Zeigarnik, Victor Novikov |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250100307
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| Publikation (Nr.) |
 EGU/EGU2014-16221.pdf |
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| Zusammenfassung |
| Developed in the 70s of the last century in Russia unique pulsed power systems based on
solid propellant magneto-hydrodynamic (MHD) generators with an output of 10-500 MW
and operation duration of 10 to 15 s were applied for an active electromagnetic
monitoring of the Earth’s crust to explore its deep structure, oil and gas electrical
prospecting, and geophysical studies for earthquake prediction due to their high
specific power parameters, portability, and a capability of operation under harsh
climatic conditions. The most interesting and promising results were obtained during
geophysical experiments at the test sites located at Pamir and Northern Tien Shan
mountains, when after 1.5-2.5 kA electric current injection into the Earth crust through
an 4 km-length emitting dipole the regional seismicity variations were observed
(increase of number of weak earthquakes within a week). Laboratory experiments
performed by different teams of the Institute of Physics of the Earth, Joint Institute for
High Temperatures, and Research Station of Russian Academy of Sciences on
observation of acoustic emission behavior of stressed rock samples during their
processing by electric pulses demonstrated similar patterns - a burst of acoustic emission
(formation of cracks) after application of current pulse to the sample. Based on the field
and laboratory studies it was supposed that a new kind of earthquake triggering -
electromagnetic initiation of weak seismic events has been observed, which may
be used for the man-made electromagnetic safe release of accumulated tectonic
stresses and, consequently, for earthquake hazard mitigation. For verification of
this hypothesis some additional field experiments were carried out at the Bishkek
geodynamic proving ground with application of pulsed ERGU-600 facility, which
provides 600 A electric current in the emitting dipole. An analysis of spatio-temporal
redistribution of weak regional seismicity after ERGU-600 pulses, as well as a response
of geoacoustic emission recorded in the wells at a distance of 7-12 km from the
emitting dipole to the ERGU-600 pulses confirmed the effects of an influence of
electromagnetic field on the deformation processes in the Earth crust and the real
existence of electromagnetic triggering phenomena. For verification of results of
field observations laboratory studies of behavior of rock samples under critical
stress-strain state and external electric actions were carried out at the spring and
lever presses, as well as at the stick-slip models simulated the seismic cycle (stress
accumulation and discharge) in the seismogenic geological fault. Various possible
mechanisms of weak electrical stimulation (electric current density 10-7-10-8 mA/cm2 at
a depth of earthquake epicenters of 5 to10 km) of deformation processes in the
Earth crust, including increased fluid pore pressure, electrokinetic phenomena,
magnetostriction, electrical stimulation of fluid migration into the fault area are considered.
However, the mechanism of electromagnetic earthquake triggering phenomena is still
open.
Based on the field observations of electromagnetic triggering of weak seismicity resulting
in a partial safe release of stresses in the Earth crust a possibility of control of seismic process
is considered for risk reduction of catastrophic earthquakes.
The results obtained from field and laboratory experiments on electromagnetic initiation
of seismic events allow to consider a problem of lithosphere-ionosphere relations
from another point of view. Keeping in mind that the current density generated
in the Earth crust by artificial electric source is comparable with the density of
telluric currents induced during severe ionospheric disturbances (e.g., magnetic
storms) it may be possible under certain favorable conditions in lithosphere to initiate
earthquakes by electromagnetic disturbances in ionosphere. A possibility of application
of these triggering phenomena for short-term earthquake prediction is discussed. |
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