COMPLETION OF GRAVITY DATABASE IN SOUTHWEST JAPAN AND PUBLICATION OF THE RESULTS

执行本项目有两个目的：(1)通过发展前三个项目(关于同一类科学研究补助金(C)：1989-1991年第01540331号、1992-1994年第04640400号和1995-1997年第07640552号)的成果，完成一个覆盖整个日本西南部地区的重力数据库；(2)公布通过这些项目获得的结果。我们项目的这一目标成功实现了。名古屋大学积累并精心汇编了日本西南部的重力数据，从那里我们完成了一个广泛而准确的重力数据库。该数据库目前包含了从39个研究所或组织收集的超过14.6万个净重力数据，空间上覆盖了日本西南部整个地区，重力数据分布非常密集。除了非常高的山脉地带等有限区域外，没有更多的重力数据空白区域。收集的数据都经过处理和编辑…名古屋大学和北海道大学都提供了更多。对所有野外数据进行了重力数据的统一处理，并对已公布的所有数据进行了全面修订。所进行的修正是：(1)对重力值进行归一化，其精度约为0.2mAl，重新调整到日本重力标准化网1996(JGSN96)；(2)将纬度和经度的坐标精度保持在0.01分钟的弧量(水平位置误差小于20米)；(3)将高程精度保持在几米误差范围内；(4)对地形改正方法和相关数据，如地理测量研究所提供的DEM数据(KS-110-1)进行修正。经过这些修改，我们在重力数据库中的所有数据上实现了1mGal的总体精度。这个高质量的重力数据库的完善使我们能够利用它更好地了解日本岛屿，不仅在地球物理意义上，而且在地球科学的其他领域也是如此。为此，我们公布了我们在日本西南部建立的重力数据库的结果。我们准备的清单是(1)大尺寸精密重力异常图；5张；(2)几本重力数据手册，以数字形式列出坐标、重力和相关数值；(3)它们的机器可读光盘形式。较少

Present project was executed with two purposes(1)to complete a gravity database to cover all over the area of Southwest Japan by developping the achievements of the former three projects(on the same category of Grant-in-Aid for Scientific Research(C) : No.01540331 in 1989-1991, No.04640400 in 1992-1994 and No.07640552 in 1995-1997), and(2)to publish the results obtained through those projects. This goal of our project was successfully achieved.Gravity data in Southwest Japan have been accumulated and carefully compiled at Nagoya University from which we have completed an extensive and accurate gravity database. This database currently containes more than 146,000 of net gravity data collected from thirty nine institutes or otganizations, and it spatially covers whole the area of Southwest Japan with very densely distributed gravity data. There is no more any vacant area of gravity data except for limitted areas such as very high mountaineos zone. Collected data were all processed and ed … More ited by both Nagoya University and Hokkaido University. A unified processing of gravity data was performed on all the field data, and an overall revision was also made on all the data already published. The revisions performed are(1)normalization of the gravity values with an accuracy of about 0.2 mGal refening to the Japan Gravity Standardization Net 1996(JGSN96), (2)keeping the coordinae accuracy by an amount of 0.01 minute of arc for both latitudes and longitudes(less than 20 meters error of horizontal position), (3)keeping the altitude accuracy by an amount within a few meters error, and(4)revisions on the method for terrain correction and related data such as DEM data(KS-110-1)provided by Geografical Survey Institute. After performing those total revisions, we accomplished an overall accuracy of 1 mGal on all the data filed in the gravity database.Completion of this high quality gravity database enables us to utilize it for more better understanding of Japanese Islands not only in geophysical meanings but also in the other fields of geo-sciences. For this aim, we publish the results of the Gravity Database in Southwest Japan we constructed. The list we prepared are(1)large sized precise gravity anomaly tnaps ; 5 sheets, (2)a couple of gravity data books listed coordinates, gravity, and related values in a digital form, and(3)their machine-readable CD-ROM form. Less