1996 Fiscal Year Final Research Report Summary
3-D modelling of Crustal movements and tectonic loading in and around Japan
| Project/Area Number |
07454103
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体地球物理学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MATSU-URA Mitsuhiro The University of Tokyo, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (00114645)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Toshinori The University of Tokyo, Earthquake Research Institute, Research Associate, 地震研究所, 助手 (70222015)
HAMAMOTO Yozo The University of Tokyo, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (90011709)
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| Project Period (FY) |
1995 – 1996
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| Keywords | earthquake cycle / crustal movement / tectonic stress accumulation / viscoelasticity / fault constitutive law / 3-D modelling / retative plate motion |
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| Research Abstract |
In the period of 1995-1996 we have conducted a research for constructing 3-D model of crustal movements and tectonic loading in and around Japan and obtained the following results.
(1)Taking the area of 3000km*3000km including Japanese Islands as a modelling region, we collected the basic geophysical data, such as surface topography, gravity anomalies, crustal structure, and hypocenter distributions of earthquakes.
(2)Applying a new inversion technique based on Akaike's Baysian Information Criterion(ABIC) to the hypocenter data of earthquakes, we determined the three-dimensional geometry of interfaces between the Pacific, North American, Philippine Sea, and Eurasian plates.
(3)We developed an efficient algorithm for computing three-dimensional viscoelastic reponse to a unit step-slip on a plate boundary. Using this algorithm, we numerically simulated the accumulation process of tectonic stress due to relative plate motion. Through the numerical simulation we demonstrated that the mechanisms of tectonic loading are essentially different between the plate interior and the plate interface. The stress accumulation at a locked portion on the plate interface is partly due to viscous drag at the base of the lithosphere(base loading) and partly due to dislocation pile-ups at horizontal edges of the locked portion(edge loading).
(4)With an inversion technique based on ABIC we analyzed levelling date for 1893-1983 on Shikiku, southwest Japan. Through the inversion analysis we reconstructed the pattern of crustal movements over the last 120 years including the occurrence of the 1946 Nankaido earthquake. The result clearly shows that the crustal movements on Shikoku include significant secular vertical motion in addition to cyclic motion related to the periodic occurrence of large interplate earthquakes at the Nankai trough.
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Research Products
(6 results)
