From Relative to Absolute Teleseismic Travel Times: The Absolute Arrival‐Time Recovery Method (AARM)
From Relative to Absolute Teleseismic Travel Times: The Absolute Arrival‐Time Recovery Method (AARM)
复制标题
从相对远震走时到绝对远震走时：绝对到达时间恢复方法（AARM）
DOI：
10.1785/0120170021
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发表时间：
2017
影响因子：
3
通讯作者：
R. Hilst
中科院分区：
文献类型：
--
作者：
A. Boyce;I. Bastow;S. Rondenay;R. Hilst
密集的、短期部署的地震仪网经常用于研究上地幔结构。然而，不同突发远震波形的记录往往比在永久观测站记录的信噪比（SNR）要低。因此，网络上的波形一致性经常被用来计算记录走线之间的相对到达时间，但这些测量结果不容易组合或直接报告给全球绝对到达时间数据库。因此，这些数据集是一种宝贵但尚未开发的资源，可以用来填补全球绝对波速层析模型的空间空白。我们开发了一种绝对到达时间恢复方法（AARM），用于从相对到达时间数据集中检索绝对时间选择，与过滤和未过滤的数据同步工作。我们还包括不确定性的相对估计，以便在随后的层析反演中用于数据加权。滤波后的波形首先通过多通道互相关进行对齐。将这些时移应用于未滤波的波形以产生相位加权堆栈。与主堆栈或每个走线的信噪比的相互关联用于加权第二个更高信噪比的堆栈。最终叠加上的第一个到达是手动选择的，以恢复对齐波形的绝对到达时间。我们在加拿大东南部最近发表的数据集上测试了AARM（约10,000次）。当与国际地震中心（ISC）数据库上现有的等效地震台站对进行比较时，约83%的aarmpick在0:5 s内一致。使用合成p波数据的测试表明，aarm产生的绝对到达时间选择精度优于0.25 s，类似于ISC公告中的不确定性。电子补充：在观测数据集上测试绝对到达时间恢复方法（AARM）的图形输出，以及包含AARM代码副本、绘图脚本和用户指南的存档。
Dense, short-term deployments of seismograph networks are frequently used to study upper-mantle structure. However, recordings of variably emergent teleseismic waveforms are often of lower signal-to-noise ratio (SNR) than those recorded at permanent observatory sites. Therefore, waveform coherency across a network is frequently utilized to calculate relative arrival times between recorded traces, but these measurements cannot easily be combined or reported directly to global absolute arrival-time databases. These datasets are thus a valuable but untapped resource with which to fill spatial gaps in global absolute-wavespeed tomographic models. We developed an absolute arrival-time recovery method (AARM) to retrieve absolute time picks from relative-arrival-time datasets, working synchronously with filtered and unfiltered data. We also include a relative estimate of uncertainty for potential use in data weighting during subsequent tomographic inversion. Filtered waveforms are first aligned via multichannel cross correlation. These time shifts are applied to unfiltered waveforms to generate a phase-weighted stack. Cross correlation with the primary stack or the SNR of each trace is used to weight a secondhigher SNR stack. The first arrival on the final stack is picked manually to recover absolute arrival times for the aligned waveforms. We test AARM on a recently published dataset from southeast Canada (∼10;000 picks). When compared with the available equivalent earthquake–station pairs on the International Seismological Centre (ISC) database,∼83% ofAARMpicks agree towithin 0:5 s. Tests using syntheticP-wave data indicate that AARMproduces absolute arrivaltime picks to accuracies of better than 0.25 s, akin to uncertainties in ISC bulletins. Electronic Supplement: Graphical output from testing of the absolute arrivaltime recovery method (AARM) on observed dataset and an archive containing a copy of the AARM code, plotting scripts, and user guide.