地震学报（英文版）2003，Vol.16Issue(1)：113-123,11.
ULF electric and magnetic anomalies accompanying the cracking of rock sample
ULF electric and magnetic anomalies accompanying the cracking of rock sample
摘要
Abstract
The anomalies of electric-magnetic field and self-potential before earthquakes are important precursory phenomena. A simulating experiment study on the variations in ultra-low frequency (ULF) magnetic field and self-potential 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 obviously 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 electric and magnetic precursors before earthquake are discussed in the present paper as well.关键词
ultra-low frequency (ULF)/self-potential/magnetic field/rock cracking/magnetic field-free spaceKey words
ultra-low frequency (ULF)/self-potential/magnetic field/rock cracking/magnetic field-free space分类
天文与地球科学引用本文复制引用
郝锦绮,钱书清,高金田,周建国,朱涛..ULF electric and magnetic anomalies accompanying the cracking of rock sample[J].地震学报（英文版）,2003,16(1):113-123,11.基金项目
Foundation item: Joint Seismological Science Foundation of China (95-07-434) and the MOST under contract 2001BA601B02. （95-07-434）
