Electromagnetic signals related to incidence of a teleseismic body wave into a subsurface piezoelectric body

This paper presents a case study of Electromagnetic (EM) signals associated with earthquakes due to the piezoelectricity of crustal rocks. For a simpl e model of crustal structure with a subsurface piezoelectric body, a mathem atical expression was obtained that describes the behavior of piezoelectric EM signals due to incidence of a teleseismic body wave. Using this express ion, we evaluated expected EM signals with physical parameters reasonable f or crustal rocks. Results of the frequency domain analysis suggested that t he intensity of the signal decreases with decreasing frequency due to decre asing stress rate at lower frequencies, and decreases with increasing frequ ency due to EM attenuation in the conducting medium at higher frequencies. However, the latter (the skin effect) was shown to be negligible at the dom inant frequency range of seismic waves so far as a shallower piezoelectric body is concerned. Numerical results also indicated a resonant feature of t he piezoelectric EM signals corresponding to geometry of the subsurface pie zoelectric body. However, numerical calculations suggested that such signal s cannot be detected except for strong motions. If detected, on the other h and, their spatial and frequency characteristics will provide information o n the geometry of the subsurface piezoelectric body.