Seismic Velocity and Density Jumps Across the 410- and 660-Kilometer Discontinuities.
Seismic Velocity and Density Jumps Across the 410- and 660-Kilometer Discontinuities.
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DOI：
10.1126/science.285.5433.1545
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发表时间：
1999-09
期刊：
影响因子：
56.9
通讯作者：
Shearer;Flanagan
中科院分区：
文献类型：
--
作者：
Shearer;Flanagan
通过模拟从这些界面反射的长周期地震波到达的观测距离关系，确定了跨越上地幔410和660公里不连续面的平均地震速度和密度跳跃。初步参考地球模型(PREM)在410公里不连续段计算的95%可信椭圆内，但在660公里不连续段允许的跳跃范围之外。目前的地幔模型似乎与410公里不连续的限制一致，但对660公里反射的幅度估计过高。跨越660公里不连续面的密度跳跃在4%到6%之间，低于地幔对流计算中常用的9.3%的Prem值。
The average seismic velocity and density jumps across the 410- and 660-kilometer discontinuities in the upper mantle were determined by modeling the observed range dependence in long-period seismic wave arrivals that reflect off of these interfaces. The preliminary reference Earth model (PREM) is within the computed 95 percent confidence ellipse for the 410-km discontinuity but outside the allowed jumps across the 660-kilometer discontinuity. Current pyrolite mantle models appear consistent with the constraints for the 410-kilometer discontinuity but overpredict amplitudes for the 660-kilometer reflections. The density jump across the 660-kilometer discontinuity is between 4 and 6 percent, below the PREM value of 9.3 percent commonly used in mantle convection calculations.