• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Bulletin of the Seismological Society of America >Improving sparse network seismic location with Bayesian kriging and teleseismically constrained calibration events
【24h】

Improving sparse network seismic location with Bayesian kriging and teleseismically constrained calibration events

机译：利用贝叶斯克里金法和受地震约束的校准事件改善稀疏网络的地震位置

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Monitoring the Comprehensive Nuclear-Test-Ban Treaty will require improved seismic location capability for small-magnitude events, The International Monitoring System (IMS) is well suited to locate events that are large enough to be recorded at teleseismic distances. However, small events are likely to be recorded on a sparse subset of IMS stations at regional- to upper-mantle distances (less than 30 degrees), and sparse-network locations can be strongly effected by travel-time errors that result from path-specific velocity model inaccuracies. In an effort to improve sparse network location capability, we outline a procedure that applies empirical corrections to travel times determined with an appropriate velocity model. More specifically, Bayesian kriging and calibration events (constrained with a global network) are used to estimate epicenter-specific travel-time corrections. For a test (sparse) network of stations, we calculate travel-time residuals for the calibration events relative to the ak135 velocity model. Travel-time residuals are assigned to the respective calibration epicenter, forming a set of spatially varying travel-time correction points. The spatial set of correction points is declustered to reduce the dimension of the observations with minimal reduction in accuracy of the travel-time corrections. We then use the declustered set of calibration points and Bayesian kriging to form continuous travel-time correction surfaces for each station of the test network. The effectiveness of travel-time correction surfaces is evaluated by locating, with and without corrections, a subset of the 1991 Racha earthquake sequence (Caucasus Mountains), for which we have accurate locations that were independently determined with a dense local network. When no travel-time correction is applied, the mean horizontal distance between the local and test network locations is 42 km, and there is a distinct bias in sparse-network locations toward the north-northwest. The mean difference between local and sparse network locations is cut to 13 km when corrections are applied, and the bias in location is significantly reduced. When calibration events in the Racha vicinity are not used to make the correction surfaces, there is still a significant improvement in location, with mean mislocations of 15 km, When corrections are not applied, only one of the locally determined locations lies within the associated 90% coverage ellipse determined with the test (sparse) network. However, by using traveltime corrections and estimates of model uncertainty determined using kriging, representative error ellipses are obtained. This study demonstrates that kriging correction surfaces based on global-network-constrained calibration events can improve the ability to accurately locate lower magnitude events while providing representative coverage ellipses. [References: 20]
机译：监测《全面禁止核试验条约》将需要提高对小震级事件的地震定位能力。国际监测系统（IMS）非常适合定位足以记录在远震距离的事件。但是，小事件很可能会记录在IMS站的稀疏子集上，该子集的区域到上地幔距离（小于30度），并且稀疏网络的位置会受到路径路径导致的旅行时间误差的强烈影响。特定速度模型的不准确性。为了提高稀疏网络的定位能力，我们概述了将经验校正应用于使用适当速度模型确定的行驶时间的过程。更具体地说，贝叶斯克里金法和校准事件（受全球网络约束）用于估计震中特定的旅行时间校正。对于站点的测试（稀疏）网络，我们计算校准事件相对于ak135速度模型的旅行时间残差。将行程时间残差分配给各个校准震中，从而形成一组空间变化的行程时间校正点。对校正点的空间集进行聚类以减小观测值的尺寸，同时最小化行进时间校正的准确性。然后，我们使用经过散布的校准点集和贝叶斯克里金法为测试网络的每个站点形成连续的行进时间校正表面。通过对1991年Racha地震序列（高加索山脉）的子集进行定位和不进行校正，可以评估行进时间校正面的有效性，对于这些地震子集，我们拥有由密集的本地网络独立确定的准确位置。如果未应用行进时间校正，则本地网络和测试网络位置之间的平均水平距离为42 km，并且稀疏网络位置向西北偏向。进行校正后，本地网络和稀疏网络位置之间的平均差异减小到13 km，并且位置偏差明显减小。当不使用Racha附近的校准事件制作校正表面时，位置仍然有显着改善，平均错位为15 km。如果不应用校正，则只有一个本地确定的位置位于相关的90个位置内用测试（稀疏）网络确定的覆盖百分比椭圆。但是，通过使用行程时间校正和使用克里金法确定的模型不确定性估计，可以获得代表性的误差椭圆。这项研究表明，基于全局网络约束的校准事件的克里金校正面可以提高准确定位较低幅度事件的能力，同时提供代表性的覆盖椭圆。 [参考：20]

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号