1994 Fiscal Year Final Research Report Summary
CONSTRUCTION OF A PRECISE GRAVITY ANOMALY MAP OVER THE EASTERN PART OF SOUTHWEST JAPAN,AND FORMATION OF GRAVITY DATABASE.
| Project/Area Number |
04640400
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体地球物理学
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| Research Institution | NAGOYA UNIVERSITY |
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Principal Investigator |
SHICHI Ryuichi NAGOYA UNIV., SCHOOL SCI., ASSISTANT PROF., 理学部, 助教授 (50022596)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Akihiko HOKKAIDO UNIV., FACULTY SCI., ASSISTANT., 理学部, 助手 (80191386)
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| Project Period (FY) |
1992 – 1994
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| Keywords | SOUTHWEST JAPAN / GRAVITY ANOMALY MAP / HIGH PRECISION / GRAVITY DATABASE / BLANK AREA OF GRAVITY DATA / STEEP GRADIENT BELT OF GRAVITY / GEOLOGICAL TECTONIC LINE / ACTIVE FAULT |
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| Research Abstract |
Present study was executed to develop the achievement of the former work of gravity study in Southwest Japan (Grant-in-Aid for Scientific Research (C), No.01540331,1989-1991). Two objects aimed ; (1) to create a gravity database with high precision and (2) to construct a prcise gravity anomaly map to cover Southwest Japan were completely performed.
We created a gravity database consisted of 85,000 by collecting data from more than 20 institutions and organizations. 29,000 among them are of our original. 9,600 data were newly measured to fill up blank area of data. By performing total revisions both for gravity reductions and coordinates readings, a high resolution of 1-0.5 mgal was obtained.
A large sized precise Bouguer anomaly map was constructed and published in the area ranged from 132ﾟ E to Fossa-Magna where covered with densely distributed data. A couple of stereographic relief maps drawn in 1 and 2 million scales were issued from Geographical Survey Institute.
Very characteristic gravity profiles are delineated on those maps.Factors recognized are : 1) Distinct linearments are delineated along major geological tectonic lines such as Median-tectonic line, 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 Pneninsula by forming two large arcs. 3) Very strong steep gradient belts of gravity of middle to smale scale are found in various places. In many cases, they are associated with active faults. 4) There are founed many linearmaents not known so far by other geophysical or geological means. They are delineated only on the gravity anomaly maps very characteristically.
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