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タイトル: 中部地方におけるGPS変位速度場の深部定常すべり断層によるモデル化と飛騨山脈の応力場
その他のタイトル: A model of Steady-state Faulting at Depths for GPS Surface Displacements and the Stress Field in the Hida Mountains in the Chubu District, Central Honshu, Japan
著者: 中川, 靖浩
川崎, 一朗
石崎, 泰男
著者(別言語): Nakagawa, Yasuhiro
Kawasaki, Ichiro
Ishizaki, yasuo
キーワード: backslip model
geodetic inversion
Hida mountains
locking fault
Niigata-Kobe tectonic line
発行日: 2001年7月25日
出版者: 東京大学地震研究所
掲載誌情報: 東京大学地震研究所彙報. 第76冊第1号, 2001.7.25, pp. 135-143
抄録: Two significant tectonic features in the Chubu district, central Honshu, Japan, are the abrupt change of the GPS displacement pattern along the Niigata-Kobe tectonic line and the anomalous direction NW-SE of compressional stresses derived from earthquake mechanisms and crater alignments of Quaternary volcanos in the Hida mountains, being deviated from the average direction of WNW-ESE of the island arc scale. We attempt to model the GPS displacements consisting of two elements, the right-lateral relative movement at a rate of ~2cm/yr between the northeast and the southwest Japan blocks and a locking fault in the upper crust along the Niigata-Kobe tectonic line. Subtracting the block movements from the GPS displacements yields a new data set of surface displacements, for which we make a geodetic inversion to obtain a backslip model of a left-lateral normal fault with the strike direction N43°E, the dip direction of -43°, the rake angle of 124°, the depth of the lower edge of 20 km, and the slip rate of ~2.9 cm/yr. Superposing the right-lateral block movements on the displacements produced by the backslip fault model recovers the original GPS displacements and a dislocation on the backslip fault becomes zero. The backslip fault turns to be the locking fault in this final situation. This model produces a compressional stress field with the direction NW-SE and a magnitude of ~10kPa/yr at a depth range of 0~10 km, which is qualitatively consistent with the anomalous compressional stress direction in the Hida mountains obtained by focal mechanisms. Based on the modeling, we propose the working hypothesis that the Niigata-Kobe tectonic line currently plays the role of the plate boundary between the Okhotsk (the northeast Japan) and the Amurian plates (southwest Japan blocks), instead of the Itoigawa-Shizuoka tectonic line.
URI: http://hdl.handle.net/2261/13211
ISSN: 00408972


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