| Experimental study on the mechanism of non-synchronism of seismo-electromagnetic radiation precursors |
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| 作者姓名： | 钱书清 吕智 任克新 |
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| 作者单位： | SHU-QING QIAN ZHI Lü KInstitute of Geophysics，China Seismological Bureau，Beijing 100081，China |
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| 摘 要： | ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｒｏｕｇｈ２０－ｏｄｄｙｅａｒｓ’ｏｂｓｅｒｖａｔｉｏｎａｎｄｓｔｕｄｙａｆｔｅｒｔｈｅ１９７６Ｔａｎｇｓｈａｎｇｒｅａｔｅａｒｔｈｑｕａｋｅ，ｔｈｅｓｅｉｓｍｏ－ｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｒａｄｉａｔｉｏｎｐｒｅｃ...
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Experimental study on the mechanism of non-synchronism of seismo-electromagnetic radiation precursors |
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| Shu-Qing Qian, Zhi Lü and Ke-Xin Ren.Experimental study on the mechanism of non-synchronism of seismo-electromagnetic radiation precursors[J].Acta Seismologica Sinica(English Edition),1998,11(5):623-629. |
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| Authors: | Shu-Qing Qian Zhi Lü and Ke-Xin Ren |
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| Institution: | (1) Institute of Geophysics, China Seismological Bureau, 100081 Beijing, China |
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| Abstract: | In order to investigate the physical mechanism of non-synchronism of seismo-electromagnetic radiation precursors, we have
made shear fracture and frictional sliding tests of rock samples by loading them in biaxial compression to model the activity
of tectonic fault zones in seismogenic region. By installing antennae of different frequency responses and acoustic transducers
around the fracture surface, the signals of electromagnetic radiation and acoustic emission in different directions and of
different frequencies produced by rock samples during their shear fracturing and frictional sliding have been recorded by
an automatic, high-speed and continuous observation system.
Some implications given by the experimental results are as follows.
| (1) |
During the process of shear fracturing and frictional sliding of rock samples under biaxial compression, large amounts of
electromagnetic signals are produced; their frequencies range from several hundred Hz to several thousand Hz.
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| (2) |
Signals received by antennae in different directions and of different frequencies are non-synchronous. They differ in amplitude
from one another, with the signal received by antennae nearest to the fracture surface being the maximum.
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| (3) |
Electric signals and magnetic signals do not appear synchronously; among them, electric signals appear more frequently and
are of larger amplitude.
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The authors hold that electric signals (E) and magnetic signals (M) are of different genetic mechanisms: electric signals
from inside the rock sample are produced by the piezoelectric effect of rock-forming crystals and net electric charge produced
by the newly created surfaces due to rock fracture, whereas magnetic signals are produced by the high-speed motion of charged
rock fragments and the ionization of ambient air excited by electrons emitted by rock in fracturing. Analysis shows that in
some moderately strong earthquakes the electric and magnetic signals also showed the phenomenon of non-synchronism: the electric
signal was earlier than the magnetic signal. If the same station observes simultaneously the electric field (underground)
and magnetic field (air), the efficiency of earthquake prediction by seismo-electromagnetic radiation precursors would be
raised effectively.
Contribution No. 98A01011, Institute of Geophysics, China Seismlogical Bureau, China. |
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| Keywords: | biaxial compression shear fracturing frictional sliding electromagnetic radiation |
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