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核幔边界作为固态地幔和液态外核的分界面,是地球深部最重要的间断面,界面两侧地震波速度和密度存在显著差异.研究表明,该界面上部的D“层存在较强的不均匀性和各向异性.研究人员利用地震学的方法,发现在某些区域D”层下部存在超低速区;近年来更有某些学者提出外核顶部某些区域可能存在一个刚性(固体)薄层,其剪切波速度约为1km/s,并认为形成该层的物理机制是在外核冷却过程中,物质分异产生轻元素聚集在外核顶部从而发生固结.分析了斐济-汤加地区深地震在美国4个主要台网(USarray,BK,US,CI)上记录到的PKKPbc波形,发现存在前驱波,从而证明非洲下部外核顶部可能存在核刚性层.通过波形拟合确定了该核刚性层的厚度约为1km.非洲下部核刚性层与前人利用P4KP和ScP波形在其他区域得到的刚性层模型较为一致.核刚性层的存在可能对核幔间的物质、能量、角动量耦合起到重要的影响.
As the interface between the solid mantle and the liquid outer core, the boundary between the mantle and the mantle is the most important discontinuity in the Earth’s deep, and there is a significant difference in seismic velocity and density between the two sides of the interface.The study shows that there is a strong D Homogeneity and anisotropy.Using seismological methods, the researchers found that in some areas there exists an ultra-low velocity region in the lower part of the D "layer. In recent years, some scholars have proposed that there may be a rigidity in some areas at the top of the outer core ), The shear wave velocity is about 1 km / s, and the physical mechanism of formation of this layer is that the light elements accumulate on the top of the outer core and solidify during the cooling of the outer core. The Fijian-Tonga Regional Deep Earthquake The PKKPbc waveforms recorded on the four major US networks (USarray, BK, US, CI) and the presence of a precursor wave suggest that there may be a nuclear rigid layer at the top of the outer sub-core in Africa. By waveform fitting, The thickness of the rigid layer is about 1 km.The lower rigid layer in Africa is consistent with the rigid layer model obtained by other predecessors using P4KP and ScP waveforms in other regions.The existence of the rigid core layer may affect the material, energy, Coupling plays an important influence.