从地震正常模式观测中内部核心异构的区域变化
Arwen Deuss1, Jessica C E Irving, John H Woodhouse
1Department of Earth Sciences, University of Cambridge, Cambridge CB3 0EZ, UK. afd28@cam.ac.uk
概括
研究人员使用地震数据在地球内核中发现了半球异质性. 这种模式类似于磁场,表明晶体在固化或马克斯韦应力过程中对齐,限制了内核超旋转.
科学领域:
- 地质物理学 地质物理学
- 地震学 地震学
- 地球科学 地球科学 地球科学
背景情况:
- 地球的磁场是由液态外核中的地力发电机产生的.
- 之前的地震研究表明,内核异性质的半球变化,但缺乏详细的约束.
研究的目的:
- 为了研究地球内核中的区域和半球异质性.
- 探索内核异构的起源及其与地球气动机的关系.
主要方法:
- 使用正常模式分割功能测量来自大地震的测量.
- 应用扩展交叉合理论来分析地震波传播.
主要成果:
- 观察到内核异构的明显区域变化.
- 在内核中确定了东半球与西半球的异质性.
- 发现了一个类似于地球磁场的模式.
结论:
- 内核异质性可能源于晶体在固化或马克斯韦应激过程中的对齐.
- 这些发现限制了内核超旋转的程度,支持振荡模型.
相关概念视频
Elastic Strain Energy for Normal Stresses
Strain energy quantifies the energy stored within a material due to deformation under loading conditions, a fundamental concept in materials science and engineering. The strain energy can be modeled when a material is subjected to axial loading with uniformly distributed stress. In this scenario, the stress experienced by the material is the internal force divided by the cross-sectional area, and the strain induced is directly proportional to this stress through the modulus of elasticity.
If...
If...
Normal Strain under Axial Loading
Normal strain under axial loading is an important concept in the field of mechanics of materials. Axial loading implies the application of a force along the axis of a material, like a column or bar. This force can either compress or stretch the material. In the context of axial loading, normal strain is the deformation experienced by the material in the direction of the loading force. It's calculated as the change in length divided by the original length of the material. This unitless ratio...
Normal Stress
Normal stress is a type of stress that occurs when forces act perpendicular, or normal, to a material's cross-sectional area. This stress often arises in structures when subjected to axial loading, which is the application of force along the axis of an object. A practical example of this can be found in bridge truss members.
When a rod is under axial loading, the internal forces and corresponding stress are normal to the plane of the section, so it is termed normal stress. It's important to...
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Magnetic Susceptibility and Permeability
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
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Elastic Strain Energy for Shearing Stresses
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...
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