Sequencing for seismic structures Structures illuminated by seismic waves at the core-mantle boundary of the Earth are traditionally found by focusing on a specific target area. Kim et al. used an unsupervised manifold learning algorithm called “the Sequencer” to automatically detect anomalies in seismic data (see the Perspective by Miller). Using this technique, they uncovered structures at the core-mantle boundary across the entire Pacific region all at once. They found many structures previously identified, but also a new, ultra-low-velocity zone beneath the Marquesas Islands. Science, this issue p. 1223; see also p. 1183 An unsupervised machine learning algorithm uncovers the structure of the core-mantle boundary region under the Pacific. Scattering of seismic waves can reveal subsurface structures but usually in a piecemeal way focused on specific target areas. We used a manifold learning algorithm called “the Sequencer” to simultaneously analyze thousands of seismograms of waves diffracting along the core-mantle boundary and obtain a panoptic view of scattering across the Pacific region. In nearly half of the diffracting waveforms, we detected seismic waves scattered by three-dimensional structures near the core-mantle boundary. The prevalence of these scattered arrivals shows that the region hosts pervasive lateral heterogeneity. Our analysis revealed loud signals due to a plume root beneath Hawaii and a previously unrecognized ultralow-velocity zone beneath the Marquesas Islands. These observations illustrate how approaches flexible enough to detect robust patterns with little to no user supervision can reveal distinctive insights into the deep Earth.

中文翻译：

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序列地震图：核心-地幔边界区域散射的全景视图

地震结构的排序传统上，通过聚焦特定目标区域来发现地球核心-地幔边界处地震波照射的结构。金等人。使用称为“序列器”的无监督流形学习算法来自动检测地震数据中的异常（参见 Miller 的观点）。使用这种技术，他们一次发现了整个太平洋地区的地核-地幔边界处的结构。他们发现了许多先前确定的结构，但也在马克萨斯群岛下方发现了一个新的超低速带。科学，这个问题 p。1223; 另见第 1183 一种无监督的机器学习算法揭示了太平洋下地核-地幔边界区域的结构。地震波的散射可以揭示地下结构，但通常以零散的方式集中在特定的目标区域。我们使用了一种称为“序列器”的流形学习算法，同时分析了数千个沿地核-地幔边界衍射的波地震图，并获得了太平洋地区散射的全景视图。在近一半的衍射波形中，我们检测到由核幔边界附近的三维结构散射的地震波。这些分散到达的盛行表明该地区拥有普遍的横向异质性。我们的分析显示，由于夏威夷下方的羽状根部和马克萨斯群岛下方以前未被认识的超低速带，发出了响亮的信号。