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Construction of a Precise Gravity Anomaly Map over the Chubu and Kinki Districts, Central Japan, and Formation of Gravity Data-Base.

日本中部中部和近畿地区精确重力异常图的构建以及重力数据库的形成。

基本信息

批准号：
01540331
负责人：
SHICHI Ryuichi
金额：
$ 1.22万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1991
项目状态：
已结题

项目摘要

Present study was executed to develop the works of gravity survey in the Southwest Japan, conducted by Nagoya University since 1978. By adding more than 8, 800 new data, 19, 555 points of our original data were updated, and compiling ones from other sources, a gravity data-base consisted of more than sixty thousands of data were formed. 2/3 of whole Japan, the southern part from 38.5ﾟ N, were covered by this data-base. The area among it, ranged from 133ﾟ E to Fossa-Magna, has very dense distribution of measurement points. Total revisions both for gravity value reductions and coordinates readings on all data file were performed. Our data-base garantees 1-0.5 mgal of comprehensive resolution and makes it possible to draw any kinds of very precise gravity anomaly maps in the whole range.Very characteristic gravity profiles are delineated and following factors are recognized : 1)Distinct linearments are delineated along major, geological tectonic lines such as Median Tectonic Line, Itoigawa-Shizuoka Geotectonic Line and so on, and active faults such as Atera Fault. 2)A very large scale of steep gradient belt of gravity is running from Suruga Bay to north-eastern Shikoku through Chita Peninsula by forming two large arcs. This belt extends to the Aso Graven in Kyushu. 3)Very strong steep gradient belts of gravity of middle to small scale are found in various places. One of the most characteristic among them is that with 15 km long along the seismic focal region of the 1984 Western Nagano Prefecture Earthquake. 4)The Kinki Triangle marks very characteristic strong negative anomaly. 5)Central Mountain Ranges have no or too small negative low anomalies. This suggests that their bodies are supported by some tectonic forces other than isostatic mechanism.

本研究是为了发展名古屋大学自1978年以来在日本西南部进行的重力测量工作而进行的。通过增加8800多个新数据，更新了19555个原始数据点，并汇集了其他来源的重力数据，形成了一个由6万多个数据组成的重力数据库。该数据库覆盖了日本全国2/3的地区，即38.5 ° N以南的日本南部地区。其中，从东经133度到大峡谷，测点分布非常密集。对所有数据文件的重力值减少和坐标读数进行了全面修订。我们的数据库保证了1-0.5 mgal的综合分辨率，可以绘制整个范围内任何类型的非常精确的重力异常图。描绘了非常有特征的重力剖面，并认识到以下因素：1）沿着主要地质构造线（如中央构造线、丝鱼川-静冈构造线等）和活动断层（如Atera断层）描绘了明显的线性。（2）从骏河湾经赤塔半岛至四国东北部，形成两条大弧，形成一条规模巨大的重力陡梯度带。这条带延伸到九州的阿索格雷文。3)在许多地方发现了很强的中、小型重力陡梯度带。其中最具特色的是1984年长野县西部地震的震源区沿着长15 km。4)近畿三角标志着非常典型的强烈负异常。5)中央山脉没有或太小的负低异常。这表明它们的主体不是由均衡机制支撑的，而是由某些构造力支撑的。