著者名 | Authors | 所属機関名 | 所属機関名(欧文) | |
1 | #木戸(仲佐)/ゆかり | Kido (Nakasa)/Yukari | 海洋科学技術センター | Japan Marine Science and Tecnology Center |
3 | 海底下深部構造フロンティアグループ | Frontier Research Program for Subduction Dynamics Group | 海洋科学技術センターのかいれい/よこすか調査船にて,1997年度 | プレートの特性の一部を明らかにすることができた. |
講演予稿:
海洋科学技術センターのかいれい/よこすか調査船にて,1997年度
より3成分地磁気測定を行っており,そのデータがかなり
まとまってきたので,報告する.特に,日本海溝と南海トラフ沿いで
測定されており,両者の磁気異常の比較から,潜り込みにともなう
プレートの特性の一部を明らかにすることができた.
abstract:
The R/V Kairei and R/V Yokosuka have conducted several
complementary geophysical surveys of the Japan Trench
and Nankai trough in 1997 and 1998. The purposes
of this study are threefold
(1) to identify and
quantify on a fine scale crustal velocity and magnetic
susceptibility variations; (2) to interpret the area's
deformation history, and; (3) to elucidate the
dynamic mechanisms by which deformation occurs
in circum-Japanese subduction zones.
Shipboard three-component magnetic (STCM) data were
acquired during legs KR97-04, 05, 06, 07, 09, KR98-04,
06, 07, and YK98-02 leg 2, and analyzed to reveal
geomagnetic features landward and oceanward of the
trench axis. The vessels surveyed approximately
20 NE-SW-, 10 N-S-, and 10 E-W-oriented lines off
the coast of Fukushima during the 100 days of surveying.
Furthermore, at least two figure-eight maneuvers were
performed during each leg to estimate shipboard
magnetization effects. 8 Hz data were filtered to remove
noise and sampling bias, and analyzed to determine whether
anomalous features were essentially two- or
three-dimensional.
The resulting dataset has been combined with
simultaneously acquired swath bathymetry and gravity
data to facilitate interpretation.
The data reveal pervasive magnetic lineations aligned
NE-SW and NW-SE on the oceanward and landward sides
respectively of the Japan Trench. In comparison,
magnetic lineations on either side of the Nankai
Trough are aligned N-S. We infer the different
lineation orientations in relation to the two trench
axes to reflect different thermal structures
in the slabs.
Future work within the framework given above is planned
to ascertain the significance of these features and
their orientations with respect to the Japan Trench
and Nankai Trough.
キーワード:
地磁気異常,日本海溝,南海トラフ,プレート,潜り込み
Keywords:
Manetic anomaly, Japan Trench, Nankai Trough, Subduction