Historical Interstation Pattern Referencing (HIPR): An Application to PcP Waves Recorded in the Antarctic for ULVZ Imaging
Historical Interstation Pattern Referencing (HIPR): An Application to PcP Waves Recorded in the Antarctic for ULVZ Imaging
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DOI：
10.1029/2021jb022741
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发表时间：
2021-10-01
影响因子：
3.9
通讯作者：
Rost, Sebastian
中科院分区：
文献类型：
--
作者：
Hansen, Samantha E.;Garnero, Edward J.;Rost, Sebastian
我们对地球深部结构的许多了解都是基于对地震波形的详细分析，这些波形在地震图上往往具有小幅度的到达;因此，叠加对于获得高于噪声水平的可靠信号至关重要。我们提出了一个新的迭代叠加方案，采用历史站间模式参考（HIPR），以提高数据质量评估。HIPR涉及比较每个记录事件的每个站点之间的旅行时间和数据质量测量值，以建立历史模式，然后将其与单个测量值进行比较。权重是根据各个站间测量差异及其与历史平均值的相似性确定的，然后将这些权重用于我们的叠加算法。这种方法不仅细化了由高质量数据组成的堆栈，而且还允许一些质量较低的事件，这些事件可能被更传统的堆栈方法所忽略，以有助于我们的研究。我们基于HIPR的叠加程序通过应用于跨南极山脉北方网络记录的岩芯反射PcP相位来说明，以研究超低速区（ULVZ）。我们专注于新西兰东部的ULVZ结构，因为我们的数据集对该地区进行了很好的采样，并且与太平洋大低切变速度省（LLSVP）的边界相吻合，从而使我们能够进一步评估可能的ULVZ-LLSVP关系。HIPR-refined堆栈显示强大的ULVZ的证据，相关的合成建模表明，在这个地区的ULVZ可能与成分不同的材料，可能已被地幔对流席卷积累沿着LLSVP边界。
Much of our knowledge on deep Earth structure is based on detailed analyses of seismic waveforms that often have small amplitude arrivals on seismograms; therefore, stacking is essential to obtain reliable signals above the noise level. We present a new iterative stacking scheme that incorporates Historical Interstation Pattern Referencing (HIPR) to improve data quality assessment. HIPR involves comparing travel-time and data quality measurements between every station for every recorded event to establish historical patterns, which are then compared to individual measurements. Weights are determined based on the individual interstation measurement differences and their similarity to historical averages, and these weights are then used in our stacking algorithm. This approach not only refines the stacks made from high-quality data but also allows some lower-quality events that may have been dismissed with more traditional stacking approaches to contribute to our study. Our HIPR-based stacking routine is illustrated through an application to core-reflected PcP phases recorded by the Transantarctic Mountains Northern Network to investigate ultra-low velocity zones (ULVZs). We focus on ULVZ structure to the east of New Zealand because this region is well-sampled by our data set and also coincides with the boundary of the Pacific Large Low Shear Velocity Province (LLSVP), thereby allowing us to further assess possible ULVZ-LLSVP relationships. The HIPR-refined stacks display strong ULVZ evidence, and associated synthetic modeling suggests that the ULVZs in this region are likely associated with compositionally distinct material that has perhaps been swept by mantle convection currents to accumulate along the LLSVP boundary.