Linear Array Data Gathering (LADG) is a method for using microearthquake observations to investigate fine structure in the Earth. There are two types of LADG, multistation and multisource. In the multisource case, seismic waveform data from many sources recorded at one station are used. We apply the multisource geometry to survey reflectors in the deep portion of the crust at Nikko-Ashio region, Central Honshu, Japan. We detect the PP and PS reflections as well as SS and SP from a partial melt zone located at 19.5 km in depth. No previous study has found the PP and PS reflections in this region. As a result of this study, we are confident that LADG for microearthquake observation is eminently useful for the survey of fine crustal structure. ¿ American Geophysical Union 1993