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| Titel |
Electromagnetic stimulation of fluid migration into fault area and earthquake triggering phenomena |
| VerfasserIn |
Victor Novikov, Elena Novikova |
| 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 |
250097234
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| Publikation (Nr.) |
 EGU/EGU2014-12790.pdf |
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| Zusammenfassung |
| A large amount of laboratory and field studies carried out over the past fifteen years clearly
showed a possibility of weak regional seismicity triggering by high-power pulses of
electric current of 0.6 – 2.5 kA injected into 4 km-length emitting dipole. These
phenomena have been verified under laboratory conditions with application of various
press equipment and spring-block models. Nevertheless, the physical mechanism of
electromagnetic earthquake triggering is not clear yet. 3-D numerical analysis of the current
density distribution in the Earth crust has shown that for conditions of the field
experiments the current value on 5-10 km depth of the earthquake epicenters typical
for the region under study (Northern Tien Shan) is 10-7 – 10-8 A/m2, which is
not sufficient to trigger earthquakes due to generation of additional stresses in the
rocks.
It is well known that fluids play an important role in the preparation and initiation of
earthquakes, and therefore, it is reasonable to consider a secondary triggering mechanism
involving fluid interaction with an electric current in the geomagnetic field resulted in
stimulation of fluid migration. It should be noted that even a small amount of fluid migrated
into a seismogenic fault under critical stress-strain state can provide a reduction of
its strength due to friction reduction and Rebinder effect resulted in earthquake
triggering. For verification of this hypothesis laboratory experiments were carried
out on the spring-block model with water injection into the contact area between
movable and fixed blocks. The experimental results confirm a possibility of application
of fluid mechanism to explain the phenomenon of weak electrical impacts on the
regional seismicity. It was shown that at the stress level in the fault area of 0.99
critical value, when the lab earthquake (slip of movable block) occurs, the threshold
value of fluid action is about of 1% of contact area/volume. For triggering the slip
of the spring-block model it is sufficient to inject 0.2-0.3 g of water into contact
area that is 0.5% of weight of granulated material (fault gauge) filled the contact
area. Application of obtained experimental results for field conditions is discussed. |
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