A function of global monitoring of nuclear explosions is the development of Earth models for predicting seismic travel times for more accurate calculation of event locations. Most monitoring agencies rely on fast, distance-dependent one-dimensional (1D) Earth models to calculate seismic event locations quickly and in near real-time. RSTT (Regional Seismic Travel Time) is a seismic velocity model and computer software package that captures the major effects of three-dimensional crust and upper mantle structure on regional seismic travel times, while still allowing for fast prediction speed (milliseconds). We describe updates to the RSTT model using a refined data set of regional phases (i.e., Pn, Pg, Sn, Lg) using the Bayesloc relative relocation algorithm. The tomographic inversion shown here acts to refine the previous RSTT public model (rstt201404um) and displays significant features related to areas of global tectonic complexity as well as further reduction in arrival residual values. Validation of the updated RSTT model demonstrates significant reduction in median epicenter mislocation (15.3 km) using all regional phases compared to the iasp91 1D model (22.1 km) as well as to the current station correction approach used at the Comprehensive Nuclear-Test-Ban Treaty Organization International Data Centre (18.9 km).

中文翻译：

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区域地震旅行时间 (RSTT) 模型的更新： 1. 断层扫描

全球核爆炸监测的一个功能是开发用于预测地震传播时间的地球模型，以便更准确地计算事件位置。大多数监测机构依靠快速、与距离相关的一维 (1D) 地球模型来快速且近乎实时地计算地震事件位置。RSTT（Regional Seismic Travel Time）是一种地震速度模型和计算机软件包，可以捕捉三维地壳和上地幔结构对区域地震走时的主要影响，同时仍然允许快速的预测速度（毫秒）。我们使用 Bayesloc 相对重定位算法使用区域阶段（即 Pn、Pg、Sn、Lg）的精炼数据集来描述对 RSTT 模型的更新。此处显示的层析反演用于改进先前的 RSTT 公共模型 (rstt201404um)，并显示与全球构造复杂区域相关的重要特征以及到达残值的进一步减少。更新后的 RSTT 模型的验证表明，与 iasp91 一维模型（22.1 公里）以及《全面禁止核试验条约》中使用的当前台站校正方法相比，使用所有区域相位显着减少了中位震中错位（15.3 公里）组织国际数据中心（18.9 公里）。