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地球的固体内核被对流的液体外核包围,由此创建了驱动地球磁场的地核发电机。用压缩体波研究地震显示出内核各向异性结构的半球性变化,但由于受地震和接收器分布状况所限,这一结论还不够充分。本文中,利用大地震的简正模式分裂函数测定结果,并基于扩展交叉耦合理论,我们观测到了区域变化和内核中东、西两半球的各向异性。这一模式与地球磁场的相似性说明在固化或组构演变过程中由Maxwell应力引起的晶体排列的凝入是产生各向异性的根源。这些观测结果限制了内核超速旋转的总量,但与振荡相符。
The Earth’s solid core is surrounded by a convective liquid outer core, thereby creating a nuclear power generator that drives the earth’s magnetic field. Seismic studies using compressional body waves show the hemispherical variation of the anisotropy of the core, but this conclusion is not sufficient due to the earthquake and receiver distribution. In this paper, using the normal mode splitting function of large earthquakes, and based on the extended cross-coupling theory, we observed the regional variations and the anisotropy of the eastern and western hemispheres of the core. The similarity between this model and the Earth’s magnetic field indicates that the coagulation of crystals caused by Maxwell stress during solidification or structural evolution is the source of anisotropy. These observations limit the total amount of kernel overspeed, but consistent with the oscillation.