| ULF electric and magnetic anomalies accompanying the cracking of rock sample |
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| 作者姓名： | 郝锦绮 钱书清 高金田 周建国 朱涛 |
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| 作者单位： | InstituteofGeophysicsandLaboratoryofTectonophysics,ChinaSeismologicalBureau,Beijing100081,China |
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| 基金项目： | Joint Seismological Science Foundation of China (95-07-434) and the MOST under contract 2001BA601B02. |
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| 摘 要： | The anomalies of electric-magnetic field and self-potential before earthquakes are important precursory phenom-ena.A simulating experiment study on the variations in ultra-low frequency(ULF)magnetic field and self-poten-tial during rock cracking was carried out in a magnetic field-free space.The results revealing in detail the whole process of the occurrences of electric and magnetic anomalises are significant for understanding the microscopic mechanism of ULF electric and magnetic signals.The experiment indicated that at the initial stage the slow changes in strain.self-potential and magnetic field with small amounts appeared firstly near the source of initial cracking,and then extended as the crack developed on.In the time domain,the self-potential anomaly emerged first and ULF magnetic field changes arose then.The shape of the ULF electric and magnetic anomaly varied ob-viously in early-,mid-and late-term of the test.The authors attributed the pulse-like changes of self-potential to the generationj and movement of the accumulated electric charges during the cracking caused by charge separation on the crack tips within the sample.While the magnetic pulses of shorter-period at the last stage of the test,may be induced by instantaneous electric current of the accumulated charege during the cracking acceleration.The technical method and the observational results of this experiment are given in detail and the microscopic mechanism of elec-tric and magnetic precursors before earthquake are discussd in the present paper as well.
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| 关 键 词： | ULF 自电位 磁场 岩石破裂 零磁空间 地震前兆 |
| 收稿时间： | 22 February 2002 |
| 修稿时间： | 1 June 2002 |
ULF electric and magnetic anomalies accompanying the cracking of rock sample |
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| Hao Jin-qi , Qian Shu-qing , Gao Jin-tian , Zhou Jian-guo and Zhu Tao.ULF electric and magnetic anomalies accompanying the cracking of rock sample[J].Acta Seismologica Sinica(English Edition),2003,16(1):113-123. |
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| Authors: | Hao Jin-qi Qian Shu-qing Gao Jin-tian Zhou Jian-guo and Zhu Tao |
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| Institution: | Institute of Geophysics and Laboratory of Tectonophysics, China Seismological Bureau, Beijing 100081, China |
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| Abstract: | The anomalies of electric-magnetic field and self-potential before earthquakes are important precursory phenom-ena. A simulating experiment study on the variations in ultra-low frequency (ULF) magnetic field and self-poten-tial during rock cracking was carried out in a magnetic field-free space. The results revealing in detail the whole process of the occurrences of electric and magnetic anomalies are significant for understanding the microscopic mechanism of ULF electric and magnetic signals. The experiment indicated that at the initial stage the slow changes in strain, self-potential and magnetic field with small amounts appeared firstly near the source of initial cracking, and then extended as the crack developed on. In the time domain, the self-potential anomaly emerged first and ULF magnetic field changes arose then. The shape of the ULF electric and magnetic anomaly varied ob-viously in early-, mid- and late-term of the test. The authors attributed the pulse-like changes of self-potential to the generation and movement of the accumulated electric charges during the cracking caused by charge separation on the crack tips within the sample. While the magnetic pulses of shorter-period at the last stage of the test, may be induced by instantaneous electric current of the accumulated charge during the cracking acceleration. The technical method and the observational results of this experiment are given in detail and the microscopic mechanism of elec-tric and magnetic precursors before earthquake are discussed in the present paper as well. |
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| Keywords: | ultra-low frequency (ULF) self-potential magnetic field rock cracking magnetic field-free space |
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