HR: 0800h
AN: T51B-0445    [Abstracts]
TI: Controlled Analogue Experiments of the Propagation of Seismic Electromagnetic Signals
AU: * Huang, Q
EM: huangq@pku.edu.cn
AF: Department of Geophysics, Peking University, Hai Dian District, Beijing, 100871 China
AB: Numerous electromagnetic signals at a broad range of frequencies associated with earthquakes have been reported. Some of these signals have been used in the studies of earthquake prediction. However, the correlation between these signals and earthquakes is still controversial. One controversy is the lack of physical nature of the generation and propagation mechanisms. Although one hypothesis considering a certain underground conductive channel was developed to explain ­øselectivity­ñ and long distance propagation of seismic electromagnetic signals (SEMS), this explanation highly depends on the existence of the expected underground conductive channel. Thus, it would be necessary to investigate experimentally the propagation of SEMS, till a scientifically credible theory has been made to explain those reported ­øselectivity­ñ and long distance propagation. Motivated by the waveguide concept, a scaled geographical model experiment on the propagation of electromagnetic waves in several waveguides was developed. Application of the above analogue experiment to the earthquakes in Greece indicated some aspect of ­øselectivity­ñ and long distance propagation may be related to the distribution of surface conductivity. In the current study, several controlled experiments have been done to investigate the following possible influences to the propagation of SEMS: background electromagnetic field, geography, border condition, source (position, intensity, frequency), and conductivity of media. The 1995 M=7.2 Kobe earthquake was chosen as an example in the current study. The results of these controlled experiments indicated that the influence from background field may be neglectable at the current S/N of the analogue experiment. The influence from border condition and source (position and intensity) may be also neglectable as long as the signals can be detected at the current sensitivity in the experiment. However, the propagation pattern of SEMS depends on geographical condition (inhomegeneity of surface conductivity) and source (frequency). The results of the above controlled experiments strengthened the reliability of the previous studies and provided some potential improvements in future analogue experiment.
DE: 2487 Wave propagation (6934)
DE: 0624 Guided waves
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting