Estabrook CH, Kind R
GeoForschungsZentrum Potsdam, Telegrafenberg, D- 14473 Potsdam, Germany.
Science. 1996 Nov 15;274(5290):1179-82. doi: 10.1126/science.274.5290.1179.
Global Seismic Network data were used to image upper-mantle seismic discontinuities. Stacks of phases that precede the PP phase, thought to be underside reflections from the upper-mantle discontinuities at depths of 410 and 660 kilometers, show that the reflection from 410 kilometers is present, but the reflection from 660 kilometers is not observed. A continuous Lame's constant lambda and seismic parameter at the 660-kilometer discontinuity explain the missing underside P reflections and lead to a P-wave velocity jump of only 2 percent, whereas the S-wave velocity and density remain unchanged with respect to previous global models. The model deemphasizes the role of Lame's constant lambda with regard to the shear modulus and constrains the mineralogical composition across the discontinuity.
全球地震台网数据被用于对上地幔地震间断面进行成像。人们认为，在PP震相之前的震相叠加是来自深度为410公里和660公里的上地幔间断面的底面反射，结果显示存在来自410公里处的反射，但未观测到来自660公里处的反射。在660公里间断面处连续的拉梅常数λ和地震参数解释了缺失的底面P波反射现象，并且导致P波速度仅跃升2%，而S波速度和密度相对于之前的全球模型保持不变。该模型弱化了拉梅常数λ相对于剪切模量的作用，并限制了间断面两侧的矿物成分。
