アフリカとアイスランドの下に描かれた複雑なシーア波速度構造

Ritsema¹, van Heijst HJ, Woodhouse

¹Seismological Laboratory, California Institute of Technology, Pasadena, CA 91125, USA. Department of Earth Sciences, Oxford University, Oxford OX1 3PR, UK.

Science (New York, N.Y.)

|December 3, 1999

まとめ

マントルのモデルは,アフリカの下の深い熱異常を明らかにし,東アフリカ・リフトの火山活動とコア・マントルの境界を結びつける. アイスランドアイスランドアイスランドアイスランド

科学分野:

地質物理学地質物理学とは地質物理学です.
地震学地震学とは
地球科学地球科学地球科学

背景:

マントルのダイナミクスを理解することは,地表の地質学的特徴を説明するために非常に重要です.
以前のモデルは,火山活動に影響を与える深層マントルの構造の範囲を完全に捉えることができなかった.

研究の目的:

地球のマントルの3次元剪定波の速度変動をモデル化するために.
東アフリカにおけるケノゾイク洪水ベースルト火山活動とアクティブリフティングの深いマントルの起源を調査する.

主な方法:

マントルの3次元剪定波速度モデルを開発した.
地震波の伝播を分析してマントルの構造と熱的異常を推測した.

主要な成果:

南東大西洋の下のコアマントル境界 (CMB) から東アフリカの下の上層マントルまで広がる低速の傾斜異常を特定しました.
この広範囲の異常は,アファールの火山活動,東アフリカ裂け目,そして遠いCMBの熱異常との関連を示唆しています.
アイスランドの下にある明確な低速の異常は,上層マントルに限定されていることが判明しました.

結論:

ケノゾイク時代の洪水ベースルト火山活動と東アフリカ裂域の活発な断層は,CMBの深い熱異常によって引き起こされる可能性が高い.
この発見は,大陸の裂け目と火山活動に深いマントルの構造が及ぼす重要な影響を強調しています.
アイスランドの火山は,東アフリカの火山と比較して,より浅い,明確な起源を持っているようです.

さらに関連する動画

05:57

Blood Flow Imaging with Ultrafast Doppler

Published on: October 14, 2020

09:19

Measuring the Structure, Composition, and Change of Underwater Environments with Large-area Imaging

Published on: April 18, 2025

関連する概念動画

01:27

Distribution of Molecular Speeds

The motion of molecules in a gas is random in magnitude and direction for individual molecules, but a gas of many molecules has a predictable distribution of molecular speeds. This predictable distribution of molecular speeds is known as the Maxwell-Boltzmann distribution. The distribution of molecular speeds in liquids is comparable to that of gases but not identical and can help to understand the phenomenon of the boiling and vapor pressure of a liquid. Consider that a molecule requires a...

01:21

Isochoric and Isobaric Processes

A thermodynamic process that occurs at constant volume is called an isochoric process. According to the first law of thermodynamics, heat supplied or removed from the system is partially utilized to perform work and change the internal energy of the system. However, in an isochoric process, the volume remains constant. Hence, the work done by the system is zero. Therefore, the exchange of heat changes the internal energy of the system only.
Suppose 1000 g of water is heated from 40 degrees...

01:27

Shear Diagram

In the study of beam mechanics, shear diagrams play a crucial role in understanding the distribution of shear forces along the length of a beam. Consider a beam AB that is supported at both ends and subjected to perpendicular loads.
First, a free-body diagram of the beam is drawn, representing all the external forces and internal reactions acting on the beam. One can calculate the reaction forces at each support by employing the equilibrium equations of force and moment. The vertical component...

01:24

Rapidly Varying Flow

Rapidly varying flow (RVF) in open channels is characterized by abrupt changes in flow depth over a short distance, with the rate of depth change relative to distance often approaching unity. These flows are inherently complex due to their transient and multi-dimensional nature, making exact analysis difficult. However, approximate solutions using simplified models provide valuable insights into their behavior.Key Features of Rapidly Varying FlowRVF is commonly observed in scenarios involving...

01:19

Polar Curves

The spirograph is a versatile tool for visualizing the relationship between geometry and mathematical representation. In particular, it demonstrates how polar coordinates offer an alternative framework for describing curves in comparison to Cartesian coordinates. Instead of specifying a point by its horizontal and vertical displacements (x, y), polar coordinates use a radius r, the distance from the origin, and an angle θ, measured counterclockwise from the polar axis. This system is...

関連する実験動画