Calculation of Sommerfeld integrals for conductive media at low frequencies

A method for accurately evaluating the Sommerfeld integral for conductive media at low frequencies that is commonly encountered in geophysics is presented. The motivation is that when we subtract an asymptotic function to the integrand, the new integral will converge much faster than the original Sommerfeld integral, which can be computed numerically while the asymptotic function can be integrated analytically by a Laplace transform. Numerical results that quantify the performance of the proposed method are presented.