Probing Asthenospheric Density, Temperature, and Elastic Moduli Below the Western United States
Probing Asthenospheric Density, Temperature, and Elastic Moduli Below the Western United States
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DOI：
10.1126/science.1202584
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发表时间：
2011-05
期刊：
影响因子：
56.9
通讯作者：
Takeo Ito;M. Simons
中科院分区：
文献类型：
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作者：
Takeo Ito;M. Simons
监测海洋潮汐负荷的反应揭示了地球内部结构的详细变化。周期性的海洋潮汐不断地在地球表面提供周期性的负载，其响应可以被利用来提供对地球内部结构的新见解。我们使用大地测量观测引起的海洋潮汐负荷的表面位移，以约束地壳和地幔上部的深度依赖模型，提供独立的估计密度和弹性模量低于美国西部和附近的近海地区。我们的观测需要软流圈顶部和底部的密度和弹性剪切模量都有很强的梯度，但在220公里的深度没有离散的结构不连续性。该模型表明，软流层具有每立方米约50公斤的低密度异常;约300°C的温度异常可以同时解释这种密度异常和推断的弹性模量共位最小值。
Monitoring the response to ocean tidal loads reveals detailed variations in Earth’s internal structure. Periodic ocean tides continually provide a cyclic load on Earth’s surface, the response to which can be exploited to provide new insights into Earth’s interior structure. We used geodetic observations of surface displacements induced by ocean tidal loads to constrain a depth-dependent model for the crust and uppermost mantle that provides independent estimates of density and elastic moduli below the western United States and nearby offshore regions. Our observations require strong gradients in both density and elastic shear moduli at the top and bottom of the asthenosphere but no discrete structural discontinuity at a depth of 220 kilometers. The model indicates that the asthenosphere has a low-density anomaly of ~50 kilograms per cubic meter; a temperature anomaly of ~300°C can simultaneously explain this density anomaly and inferred colocated minima in elastic moduli.