1:1,000, 000 bathymetric charts

Abstract

The Hydrographic Department of Japan (Nippon) is planning to publish a 1: 1,000,000 bathyrnetric chart series which covers the continental margin around Japan in five sheets. Of those sheets planned, two sheets （“HOKKAIDO" and “NORTH”EAST NIPPON”） have already been published. This bathymetric chart series is the first one to represent the details of the continental margin including trenches and back arc basins around Japan by 100 meter-interval depth contours, and from this viewpoint, may have historical significance on the history of bathymetric chart preparation in Japan. Taking this opportunity, the authors tried to discuss the basic specifications of preparing this series, and to summarize the characteristic submarine topography covered by the two sheets by way of regional description. The basic specifications discussed are as follows: The overall publication plan, expression of data control, projection, graticule and graduation, depth contours and soundings, representation of land features, nomenclatures and geographical names of sea bottom features and color expression are presented. Submarine topography of the sea area studied is divided into three provinces by characteristics and origin. 1. Japan Sea side (Hokkaido，North-East Nippon) 2. Sea of Okhotsk side (Hokkaido） 3. Pacific Ocean side (Hokkaido，North-East Nippon) In the present paper, the characteristics of submarine topography (continental shelf, continental slope, continental borderland, deep sea basin, trench and others) based on the. results of morphometry and reference, were first described for each province, and then problems relating to the origin of the Japan Sea, deep continental shelf, old sea level, wave-like distribution of continental shelf edge, origin of deep sea plains, etc., were additionally discussed.