Multi-dipole observation system and study on the abnormal variation of the geoelectric field observed at Capital Circle area before the Wen’an MS5.1 earthquake |
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| Authors: | Qin-zhong Ma |
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| Institution: | (1) Earthquake Administration of Shanghai Municipality, Shanghai, 200062, China |
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| Abstract: | On July 4, 2006, a M
S5.1 earthquake occurred in Wen’an county of Hebei Province of which the epicenter is near the Beijing city. The six geoelectric
field monitoring stations have been in operation for several years around the Beijing area to examine the relationship between
electric field changes and earthquake. This paper firstly explains the principle of the eliminating noise method by using
multi-dipole observation system of the geoelectric field. Then the data observed at the stations are studied and a lot of
abnormal signals preceding the Wen’an earthquake are selected, of which five abnormal signals of the geoelectric field are
finally recognized as the precursory signals. The result shows that ➀ there probably exists the precursory signals of the
geoelectric field preceding the Wen’an earthquake; ➁ there are sensitive sites in the spatial distribution of the abnormal
variation of the geoelectric field before the quack; ➂ the anomalous signals do not appear synchronously, and their durations
are not same at different stations; ➃ the amplitudes of the abnormal signals recorded at Baodi station are small, but large
at Changli station, while the latter is farther from the epicentral area than the former.
Foundation item: Joint Seismological Science Foundation of China (106079). |
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| Keywords: | Wen’ an earthquake geoelectric field multi-dipole observation signal recognition |
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