Inner-core Fine Structure and Rotation from Array Studies

0001126Vidale该项目提出测量地球内核的精细尺度结构，并使用新发现的内核散射波（ICS）估计其旋转。 PI最近显示了内核边界反射（PkiKP）之后的扩展（200 s）散射波列，这可以通过分布在内核外半部的短波长（3.5 km）小幅度（3%）刚度变化来解释。 这些初步结果表明，内核是我们星球上最不均匀的地方之一。 该项目将积累一个来自不同震中范围的阵列ICS波数据库，研究将能够对不同物理性质的振幅变化进行约束。 ICS波的分析为内核运动提供了一个简单的测试。 在LASA记录的1971年和1974年发生的两次新地岛核试验所产生的散射波，相隔不到一公里，显示出ICS波的微小但连贯的变化。 在大圆路径以西的内核中，1974年散射的能量比1971年早0.1 s。 相反的趋势出现从东方散射。 这种模式表明内核的旋转速度为每年0.15度。 为了确认初始结果，检验内核自转速率的时间稳定性，确定内核超自转极点，还需要对附加事件进行研究。

0001126VidaleThis project proposes to measure the fine-scale structure of the Earth's inner-core and estimate its rotation using newly discovered inner-core-scattered waves (ICS). The PIs recently showed an extended ( 200 s) scattered wavetrain following the inner-core-boundary reflection (PkiKP), which can be explained by short-wavelength (3.5 km) small amplitude ( 3%) stiffness variations distributed across the outer half of the inner-core. These initial results indicate the inner core is one of the more heterogeneous places in our planet. This project would amass a database of array ICS waves from different epicentral ranges, the research will be able to place constraints on the amplitude variation of distinct physical properties. Analysis of ICS waves provides a simple test for inner-core motion. Scattered waves generated by two Novaya Zemlya nuclear tests separated by less than a kilometer occurring in 1971 and 1974 recorded at LASA show small but coherent changes in the ICS waves. Energy scattered in the inner core to the west of the great-circle path is up to 0.1 s earlier in 1974 than 1971. The opposite trend appears for scattering from the east. This pattern suggests an inner-core rotation rate of 0.15 degrees per year. Investigation of additional events is needed to confirm the initial result, test for the temporal stability on the inner-core-rotation rate, and determine the inner-core super-rotation pole.