江西数字地震台网近震震级偏差与量规函数关系的研究

Study on the Relationship Between Magnitude Deviation of Near Earthquakes and Calibration Function in Jiangxi Digital Seismic Network

采用江西数字地震台网数字地震记录资料,选取自2007年10月正式运行至2009年12月所记录的138次ML≥1.5的地震事件,计算了各台站单台震级与台网平均震级的偏差、平均偏差和标准偏差,从震级偏差频次分布、量规函数、平均周期等因素对单台震级的影响上作了定量统计和分析。结果表明:①除九江、赣州、石城、都昌、高安5个台的震级与台网的平均震级偏差比较大外,其余台站均比较小;②目前所用量规函数在震中距小于40 km时偏小,大于330 km时偏大,给出了量规函数校正值,③平均周期小于0.17 s时,变得极不稳定,离散程度明显增大,这种情况应该是由于单台震中距超过300 km的样本数太少所导致的。

To calculate the deviations between single station magnitudes and average ones; the paper selected 138 ML≥ 1.5 earthquake events recorded on Jiangxi Digital Seismic Network from October 2007 to December 2009. The magnitude deviations of earthquake is analyzed on the frequency distribution, calibration function and average period quantitatively and statistically. The results show： 1） The magnitude deviations at all stations are relatively small, except at Jiujiang, Ganzhou, Shicheng, Duchang and Gaoan stations. 2） The deviation of calibration function currently used is larger when the epicentral distance is less than 40 km or more than 330 kin, and the corrections of calibration function are given in this paper. 3） The deviations between single station magnitudes and average ones become very unstable when average period is larger than 0.17s, which is possibly due to undersampling that epicentral distance of single station is more than 300 km.