Abstract:
We analyze theoretically two possible sources of co-seismic electromagnetic
response to the propagation of various types of seismic waves caused either by the electrokinetic
phenomena or geomagnetic inductive effect. The differences between these two
generation mechanisms have been examined for different types of seismic waves (P, S, and
Rayleigh-Love). Theoretical relationships describing the dependence of the co-seismic
signal amplitude, polarization and apparent impedance on the earthquake seismic moment
and magnitude have been derived as a function of distance. We indicate an observational
possibility to discriminate seismo-electrokinetic and seismo-magnetic effects and to estimate
their contribution into a recorded co-seismic electromagnetic signal. Magnitudes and
polarization of these signals are shown to depend strongly on the type of seismic wave and
local crust parameters, such as streaming potential coupling coefficient, conductivity,
inhomogeneity, etc. Co-seismic electromagnetic signals, though not directly applied for
earthquake prediction, contain a useful information on local crustal phenomena, and can be
used to identify ‘‘sensitive’’ zones perspective for the monitoring of precursory electromagnetic
disturbances.