Determination of teleseismic relative phase arrival times using multi-channel cross-correlation and least squares
Determination of teleseismic relative phase arrival times using multi-channel cross-correlation and least squares
复制标题
DOI：
--
复制
发表时间：
1990-02
影响因子：
3
通讯作者：
J. VanDecar;R. Crosson
中科院分区：
文献类型：
--
作者：
J. VanDecar;R. Crosson
我们开发了一种半自动方法，用于确定区域网络上记录的远震的准确相对相位到达时间和不确定性估计。我们的分析首先使用单迹相位选取算法获得初步到达时间。然后，对于每对可能的迹线，我们搜索其互相关函数的最大值，以获得相对延迟时间。根据事件幅度，通过使用包含 2 至 4 秒相位初始能量脉冲的相关窗口可以获得最佳结果。然后，使用互相关导出的延迟时间来生成超定线性方程组，其解是一组优化的相对到达时间。我们使用最小二乘法求解这些时间。通过自动重新评估互相关函数来消除周期跳跃，从而产生较高的方程残差。定时不确定性的定量估计是从与每条迹线相关的方程残差的方差中获得的。使用来自华盛顿地区地震仪网络的数据，我们发现对于相当高质量的事件，到达时间估计的均方根不确定性约为采样间隔（0.01 秒）。尽管波形特征存在显着差异，但对于来自相同地理位置的事件，延迟异常的再现性非常好。在对卡斯卡迪亚俯冲带深层结构的研究中，我们对残余模式随方位角的变化进行了初步检查。
We have developed a semi-automated method of determining accurate relative phase arrival times and uncertainty estimates for teleseisms recorded on regional networks. Our analysis begins by obtaining preliminary arrival times with a single-trace phase-picking algorithm. For each possible pair of traces we then perform a search for the maximum of their cross-correlation function in order to obtain relative delay times. Depending on event magnitude, the best results are obtained by using correlation windows containing 2 to 4 sec of the initial energy pulse of the phase. The cross-correlation derived delay times are then used to generate an overdetermined system of linear equations whose solution is an optimized set of relative arrival times. We solve for these times using least squares. Cycle skipping is eliminated through the automatic re-evaluation of cross-correlation functions which yield high equation residuals. Quantitative estimates of timing uncertainty are obtained from the variance of equation residuals associated with each trace. Using data from the Washington Regional Seismograph Network, we have found that for reasonably high-quality events, the rms uncertainty in arrival time estimates is on the order of the sample interval (0.01 sec). Reproducibility of delay anomalies is excellent for events from the same geographic locations despite significant differences in waveform character. In connection with a study of the deep structure of the Cascadia Subduction Zone, we include a preliminary examination of the variation of residual patterns with azimuth.