Amplitudes at the antipode

Seismic amplitudes of 1 Hz compressional waves at the antipode are estimated using the body-wave magnitude formula and corrections for focusing at the antipode. Compressional wave amplitudes are found to be larger at the antipode than at other distances outside of the source region itself. Ellipticity effects at the antipode are found to be significant only for PP away from the earth's poles and for PKP near the equator. The effects of lateral heterogeneity on antipode focusing are estimated. Implications for monitoring nuclear explosions are discussed. An antipode experiment using small (12 ton) chemical explosions opposite a seismic array is found to be viable.