The Quaternary stratigraphy of subsurface geology of the Osaka Plain has been mainly built up with deep drilling cores and detailed lithostratigraphy, tephrostratigraphy, and biostratigraphy has become clear. On the other hand, seismic reflection surveys in the Osaka Plain have been carried out along 13 lines. But, acoustic features and similarity of reflectors of each seismic profiles were not synthetically discussed until now. In this paper, seismic stratigraphic classification of seismic profiles in the Osaka Plain is carried out from detailed description of reflectors, and the relations between this seismic stratigraphic division and lithostratigraphic division are examined. As a result, it has become clear that there are similarities of acoustic facies in the different seismic profiles in the Osaka Plain. The seismic zones of Quaternary sediments in the Osaka Plain are divided into two zones, seismic zone N and seismic zone P. In seismic zone N shows very poor to non-continue and non-clear reflectors, which can be correlated with the Miyakojima Formation. In seismic zone P shows good to poor continue and clear reflectors, which can be correlated with the Tanaka Formation. On the basis of continuity of reflectors, variety of reflector interval, and strength of reflection, the seismic zone P is divided into three sub seismic zones as seismic zone Pa, seismic zone Pb, and seismic zone Pc which can be correlated with the horizon between Ma -1 to Ma 2, Ma 2 to Ma 7, and above Ma 7, respectively. It is considered that these seismic stratigraphic divisions will expect to become important basic data in the Osaka Plain.
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