Abstract In this article, we propose a new inversion scheme to calculate the melt volume fractions from observed seismic anomalies in a low-velocity layer (LVL) located atop the mantle transition zone. Our method identifies the trade-offs in the seismic signature caused by temperature, solid composition, melt volume fraction, and dihedral angle at the solid-melt interface. Using the information derived from the amplitude of P-to-S conversions beneath the western US, we show that the multiple permissible solutions for melt volume fractions are correlated to each other. Any possible solution can be directly transformed into alternative solutions whilst leaving the model output unchanged. Hence, the additional solutions can be rapidly derived given an initial solution. The calculation of multiple solutions reveals the universal properties of the whole range of solutions. A regional-averaged melt volume fraction of at least 0.5% occurs in every solution, even though a unique interpretation does not exist.

中文翻译：

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一种分析上地幔地震低速层物理性质的反演方法

摘要 在本文中，我们提出了一种新的反演方案，用于根据位于地幔过渡带顶部的低速层 (LVL) 中观测到的地震异常计算熔体体积分数。我们的方法确定了由温度、固体成分、熔体体积分数和固熔体界面的二面角引起的地震特征的权衡。使用来自美国西部下方 P-to-S 转化幅度的信息，我们表明熔体体积分数的多个允许解是相互关联的。任何可能的解决方案都可以直接转换为替代解决方案，同时保持模型输出不变。因此，在给定初始解的情况下，可以快速推导出附加解。多解的计算揭示了整个解的普遍性质。尽管不存在独特的解释，但每个溶液中都会出现至少 0.5% 的区域平均熔体体积分数。