Inner-core Fine Structure and Rotation from Array Studies

阵列研究的内核精细结构和旋转

• 批准号: 0001126
• 负责人: John Vidale
• 金额: $ 17.1万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-10-01 至 2005-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0001126&HistoricalAwards=false
• 关键词: Inner; core; Fine; Structure; Rotation

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.

0001126Vidale该项目提议测量地球内核的精细结构，并利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秒）散射波列，这可以通过分布在内核外半部分的短波长（3.5公里）小幅度（3％）刚度变化来解释。 这些初步结果表明内核是地球上异质性最强的地方之一。 该项目将收集来自不同震中范围的阵列 ICS 波数据库，该研究将能够对不同物理特性的振幅变化施加限制。 ICS 波的分析为内核运动提供了一个简单的测试。 LASA 记录的 1971 年和 1974 年发生的两次相距不到一公里的新地岛核试验产生的散射波显示了 ICS 波的微小但连贯的变化。 1974年，大圆路径以西内核中的能量散射比1971年提前了0.1秒。从东部散射的趋势则相反。 这种模式表明内核每年旋转 0.15 度。 需要对其他事件进行调查来确认初始结果，测试内核旋转速率的时间稳定性，并确定内核超级旋转极点。