Abstract
J-Array is a large-aperture short-period seismic array extending over the whole Japan with its dimension. being 3000 km in length and 300-500 km in width. It counts 218 stations. The recording system and the present status of J-Array program are presented in detail. Array analyses of a large volume of seismic waveform data recorded at J-Array enable us to detect even small-amplitude seismic waves refracted, reflected, converted or scattered at seismic velocity discontinuities or inhomogeneities existing in deep portions of the Earth, which convey information on the detailed structure and the regional variation of the central core, the lower mantle and also the upper mantle.
