Abstract
The frequency temporal analysis of the electromagnetic field recorded from 30 May 1995 to 24 August 1995 at a site about a hundred kilometer North of the epicenter of the 21 July 1995 Yong Deng earthquake (China) has shown a clear systematic variation on an electric dipole. In the ultra low frequency range from 0.01 to 0.0005Hz, a three-fold decrease of the frequency of the maximal energy concentration was observed, on 30 May 1995 from 0.005 to 0.0010Hz few hours at the time of the earthquake. This decrease was nearly monotonic, with superimposed small scale step-like fluctuations, and continued after the Yong Deng earthquake for about two weeks, when the minimum of 0.001Hz was observed just before its abrupt disappearance.The ULF signal is observed on one of the four electric dipoles. The instrumentation and the data acquisition system do not generate this signal. The signal could be generated by an electrokinetic effect depending on stress field changes in the local environment of one or two probes. The results need further understanding and interpretation.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
