首都圈数字地震台网的微震定位实验

TEST OF EPICENTER DETERMINATION OF MICROEARTHQUAKES RECORDED BY THE DIGITAL SEISMIC NETWORK IN CAPITAL CIRCLE

新建成的首都圈数字地震台网由 10 7个数字地震台站组成 ,其地震监测和定位能力需要检验。此文主要目的是为评估首都圈数字地震台网的地震活动监测能力提供参考依据。在地震定位中 ,应充分发挥数字地震记录的优势 ,采用相应的数字地震记录处理技术 ,提高地震定位的可靠性和精度。采用滤波、偏振及台站扫描、震相追踪等数字技术 ,提高了震相识别的可靠性和精度 ,并用Geiger方法对 2 0 0 1年首都圈数字地震台网记录到的 7个网内及网缘微震 (ML<2 .0 )进行了精确定位 ,还通过对爆破的定位来检验程序和方法的可靠性和精度。结果表明 ,震中定位误差估计小于2km ,震源深度误差估计小于 3km。

The newly developed Digital Seismic Network in Capital Circle consists of 107 stations, the seismic monitoring and epicenter determination capabilities of which need to be verified. In epicenter determination, we should bring the superiority of digital seismic record into full play, and improve the reliability and precision of epicenter determination by using the corresponding digital processing technique. In this study, several digital processing techniques, including digital filtering, polarization analysis, station scanning and phase tracing, are used for improving the phase identification in the epicenter determination. Totally, 7 microearthquakes ( M L<2.0) recorded by the Digital Seismic Networks in Capital Circle in 2000 were located precisely by using the Geiger method. In addition, the reliability and precision of the method and program have been verified by determining the epicenters of artificial events. It is shown that the error of epicenter location is less than 2.0km and the error of focal depth determination is less than 3.0km. The results of this study can be used for evaluating the seismic monitoring capability of the Digital Seismic Network in Capital Circle.