新疆地区地震目录最小完整性震级和台网科学布局研究

摘要

The minimum magnitude of completeness (Mc) is a fundamental and important parameter for earthquake study. It is also a key factor for evaluating detection ability of a seismic network. In the Xinjiang region with intense tectonic movement earthquakes frequently occur and geographic distribution of seismic stations is complicated. The analysis of Mc can provide useful information for seismic risk evaluation and scientific layout of seismic stations in this re-gion. For the 5 development periods of Xinjiang seismic network we examined Mc spatial distribution in each period by using OR relation analysis, and investigated temporal variation of Mc distribution for every seismic zone by means of multi-parameter description. The result shows that the Mc distribution is spatially inhomogeneous and seismic monitoring capability is rather good for Tians-han region, but it is poor for western Kunlun and other regions. For different period of seismic network development, especially since the establishment of digital seismic network during the "10th five year project", the Mc is ML1. 5-2. 0 in Tianshan and Altai seismic zone, and is ML2. 0 in northern region of western Kunlun seismic zone. Besides, the relation between Mc and station-epicenter distance, and azimuthal coverage of stations, are studied based on the data from seismological observation reports in Xinjiang region since 1988, and the scientific approach of optimizing seismic network and advancing seismic monitoring capability are discussed. It is assumed that adding short epicenter distance stations and improving azimuthal coverage of stations are necessary for advancing seismic monitoring capability in Xinjiang region.%地震目录的最小完整性震级M.是地震学中最基础、最重要的研究内容之一,也是地震观测台网效能评估的关键.本文对构造活动剧烈、地震活动水平高、台站地理分布复杂的新疆地区开展M研究,试图为该地区的地震危险性评估和台站科学布局等研究提供参考资料.基于新疆地震台网发展的5个阶段划分,采用基于G-R关系的交互式分析方法,研究了M.的空间分布特征；采用多参数方法研究了分区的M.时间演化特征.结果表明,新疆地区M:的空间分布存在较大的非均匀性,天山地区监测能力较好,西昆仑地震带等地区相对较低.对于地震台网的不同发展阶段,尤其是“十五”数字地震台网运行以来,天山地震带、阿尔泰地震带M:可达ML1.5-2.0,台站相对稀疏的西昆仑地震带北段可控制在ML2.0左右.此外,利用新疆地区1988年以来的经过数字化整理的地震观测报告,考察了M:与震中距和台站张角的关系,讨论了台网科学布局和提升地震监测能力的科学途径.结果表明,通过增加近台数量和台站-事件张角上的密度,仍是提升新疆地区地震监测能力的有效途径.