多方法联合评估河套地震带的台网监测能力

使用删除余震后的地震目录, 综合运用多种方法进行M_c值的定量计算和对比分析, 对河套地震带的台网监测能力的时空变化进行分析判定。 结果表明, 1970年以来, 河套地震带的台网监测能力整体呈现逐步增强趋势。 在Bootstrap次数为200的条件下, MAXC方法确定的研究区整体M_c值为M_L2.7±0.07, δM_c的分布基本控制在M_L0.1～0.4之间, EMR方法给出的M_c时序变化范围是M_L1.6～2.8; 多方法联合测定的M_c值变化范围为M_L1.8～3.3, R/S检验给出的结果是M_L3.4。 对比发现, 余震删除对最小完整性震级的计算有一定影响, R/S检验求取的最小完整性震级在余震删除前后相差M_L0.9; 整体来看, M_c值随时间演化逐渐减小, 较小时空范围内的M_c值仍有显著的非均匀性变化现象, 不同时段内台网布局的空间调整以及地震事件的时空非均匀性活动可能是主要原因。

Multi-method Assessment of Network Monitoring Capabilities for the Hetao Seismic Belt

Using earthquake catalogue after deleting aftershocks, we combined several kinds of methods to quantitatively calculate and analyze the least magnitude of completeness (M_c) in the Hetao seismic belt. We analyze and judge temporal changes of network monitoring capabilities for this belt. The results show that, since 1970, Hetao seismic belt's network monitoring capabilities has been gradually increasing. Under the condition of Bootstrap 200 times, the M_c value is M_L2.7±0.07 and the distribution of δM_c is basicly controlled in M_L0.1～0.4 by the MAXC methods, however the M_c value is M_L1.6～2.8 by the EMR methods. The range of M_c by the multi-method determined is M_L1.8～3.3, the result of R/S test is M_L3.4. By comparison, we found that aftershock deletion has notable influence in the calculation of M_c, in particular, M_c had M_L0.9 deference before and after deleting the aftershocks by R/S test. On the whole, M_c is decreasing with time, but there are significant non-uniformity changes in small spatial and temporal scales. Maybe, the spatial adjustment of network and the non-uniformity activity of earthquakes are the main factors.