昆明数字遥测台网近震震级的测定

Determination of local earthquake magnitude in Kunming Digital Telemetered Network

2000年1月至2002年8月昆明数字遥测台网26个子台记录的718个地震的数字地震记录,通过系统的传递函数,仿真为短周期的DD-1地动位移记录和中长周期DK-1的地动速度记录,记录仿真前后均测定地震震级,分别记为Msz和Mfz;对其中云南常规模拟地震台网40个台站记录的259个地震,也从记录图纸测定了地震震级,记为Mmn。对Mfz、Msz和Mmn进行系统的比较表明:在1.0≤ML<2.5的地震中,仿真后所测震级Mfz比仿真前所测震级Msz平均偏高0.16;在2.5≤ML≤2.9的地震中,Mfz比Msz平均偏高0.12;而在3.0≤ML≤3.9的地震中,Mfz与Msz的平均偏差基本为0;ML≥4.0的地震中,Mfz比Msz平均偏小0.02;MS的仿真震级Mfz比Msz平均偏高0.04;特别由模拟记录所测的震级Mmn与Mfz的平均偏差基本为0;不同震级间的差别基本呈正态分布。

The broadband digital speed seismograms, from 718 near earthquakes recorded on 26 digital stations of the Kunming Digital Telemetered Network during 2000.01～2002.08, have been emulated by means of the digital seismograph system s transfer function to get displacement seismograms of ground motion recorded on the short period seismograph DD-1 and speed seismograms on the moderate period seismograph DK-1. The magnitude has been determined for the 718 events before and after the emulating digital speed seismograms and denotes as Msz, Mfz, respectively. The magnitude of 259 among the above 718 events, recorded on 40 conventional short period analogue seismograph stations of Yunnan Network, has been also determined by means of the analogue seismograms and denotes as Mmn.The careful comparison between Mfz and Msz , Mfz and Mmn indicates that, on the average, Mfz is 0.16 greater than Msz at a range of 1.0≤ML < 2.5, Mfz is 0.12 greater than Msz at 2.5≤ML≤2.9, Mfz is almost the same as Msz at 3.0≤ML≤3.9, Mfz is smaller 0.02 than Msz at ML≥4.0, especially Mfz is almost the same as Mmn. For MS, Mfz is greater 0.04 than Msz, and the difference between Mfz and Msz or Mfz and Mmn is basically on normal distribution.