地下の構造から予想される地表の重力と実測の重力との差から求められる海山, 海溝下のリソスフェアの異常と, 海溝, 海山の相互作用

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書誌事項

タイトル別名
  • Lithosphere Anomalies beneath Seamounts and Trenches, Derived from Difference between Observed Gravity and Expected Gravity from Subterranean Structure, and Mutual Interaction between the Trenches and Seamounts
  • チカ ノ コウゾウ カラ ヨソウサレル チヒョウ ノ ジュウリョク ト ジッソ

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抄録

Lithosphere anomalies beneath seamounts and trenches are derived from differece between observed gravity and expected gravity from subterranean structure, and the following results have been obtaind;<br>(1) Negative free air gravity anomaly surrounding seamount in the Mid-Pacific is interpreted by thinner lithosphere under the seamount. This anomalous lithosphere is 20-30km thinner in thickness and its horizontal extent is once or twice as large as horizontal scale of the seamount. The seamount is expected to be supported with buoyancy of asthenosphere, the density of which is smaller than that of lithosphere.<br>(2) Outer gravity high seaward of trench is interpreted by thicker and heavier lithosphere near the trench. Lithosphere will sink downwards due to its excess weight at the trench. According to the sinking of lithosphere, the trench axis will move seawards.<br>(3) If a trench axis approaches seamounts, moving rate of the axis near the seamounts will be slown down. Because, thinner lithosphere under the seamounts cannot sink downwards until its thickness become larger than normal. This mechanism can explain the origin of the large negative free air gravity anomalies landward of trench junctions as well as the origin of nodes of trenches.

収録刊行物

  • 地震　第２輯

    地震　第２輯 30 (3), 359-368, 1977

    公益社団法人 日本地震学会

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