Electromagnetic wave radiation from a SLF/ELF underground horizontal electric dipole (HED) related to seismic activity is discussed. In order to estimate the effects on the electromagnetic waves associated with the seismic activity, SLF/ELF waves radiated from a possible seismic current source modeled as a electric dipole, are precisely computed by using a speeding numerical convergence algorithm. In 1999, Barrick proposed an algorithm, which was only suitable to solve the electromagnetic problems under the ideal electric conductor condition. To solve the problems under the non-ideal electric conductor condition, we have further developed Barrick's method and proposed a speeding numerical convergence algorithm. The variations of the electromagnetic field along the propagation distance and the altitude, as well as the frequency during day and night are analyzed and calculated. It takes 0.5 minute to calculate the sum of the series by my algorithm, while it needs 15 minutes by calculating directly the sum of the series. Our algorithm is compared with the calculation directly the sum of the series algorithm, and two algorithms agree with each other very well. Therefore, our algorithm is correct. Schumann resonance is also verified. [ABSTRACT FROM AUTHOR]