利用PMC方法评估山西测震台网的地震监测能力

Assessment of Earthquake Monitoring Capability of Shanxi Seismic Network based on PMC Method

为科学评估山西测震台网的监测能力,采用“基于概率的完整性震级”PMC方法,以山西测震台网产出的地震观测报告为输入,计算了山西测震台网57个台站对周边地震事件的检测概率、测震台网的合成检测概率及最小完整性震级。单台检测概率结果显示:PMC方法相对客观地反映了57个台站对地震事件的检测能力,山西中部的5个台站,由于台站密度大且布局合理,对较小震级的地震都有较高的检测能力,位于山西北部和南部省界附近的台站,检测能力较弱。合成检测概率结果表明:检测概率高值区域主要集中在山西忻州、太原、晋中、临汾以及大同和长治的部分地区一带,是监测能力最强的地区,山西80%的地区能监测到M_(L)1.0及以下的地震;共享了邻省17个台站后,山西北部及南部省界附近区域的最小完整性震级M_(P)达到1.7,相比中部地区而言,监测能力较弱。为提高山西测震台网的监测能力,需在山西北部及南部边界地区增加台站密度,或从邻省引入更多的台站,进一步优化山西测震台网的台站布局。

To evaluate monitoring ability of Shanxi seismic network scientifically,taking the seismic observation report produced by Shanxi seismic network as the input,detection probability of 57 stations of Shanxi seismic network to earthquake events surroundings,synthetic detection probability and minimum integrity magnitude of seismic network are calculated by PMC method of integrity magnitude which is based on probability.It is illustrated by detection probability result of single station that PMC method relatively objectively reflects the capability of 57 stations to earthquake events,and that 5 stations in central Shanxi have high detection capability to earthquakes of small magnitude because of large density and reasonable layout of stations and that Stations located near the northern and the southern provincial boundary of Shanxi has relatively weak detection capability.The result of synthetic detection probability shows that the high detection probabilities are mainly concentrated at Xinzhou,Taiyuan,Jinzhong,Linfen and some areas of Datong and Changzhi of Shanxi,which are areas of the most strong monitoring capacity and that earthquakes of M_(L)1.0 and below can be monitored in 80%regions of Shanxi,and that after sharing 17 stations in the neighboring province,minimum integrity magnitude M_(P) near the northern and the southern provincial boundary of Shanxi reaches 1.7,whose monitoring capacity is weak,compared to the central region.To improve monitoring capacity of Shanxi seismic network,station density is needed to add in the northern and southern provincial boundary of Shanxi or more stations from the neighboring provinces are introduced to further optimize the station layout of Shanxi seismic network.