山东李楼煤矿近场地震波衰减关系与矿震震级测定方法研究

Near-field Seismic Wave Attenuation Relationship and Magnitude Determination Method for Mining-induced Earthquakes in Lilou Coal Mine of Shandong Province

摘要:

矿震的震级较小,高频地震波丰富,仅能利用5km以内的地震台站进行监测。为得到山东李楼煤矿近场地震波的衰减规律和近震震级M_L的量规函数,在李楼煤矿布设了由36个地面台站和33个井下巷道台站组成的立体观测台网,进行了7次爆破实验,取得的主要成果如下: ①利用这些高质量的近场观测资料,得到李楼矿区5km内地面台站和井下巷道台站S波衰减规律,其中在1km内S波随震源距的衰减非常迅速; ②利用垂直向和水平向资料,分别得到李楼矿区垂直向和水平向地方性震级的量规函数; ③分别利用垂直向和水平向资料和量规函数,测定了7次爆破的震级,结果表明利用不同震源距测定的单台震级一致性较好,且利用水平向资料测定的震级与用垂直向资料测定的震级相差在0.1以内; ④根据国家标准GB 17740—2017《地震震级的规定》,在5km以内地方性震级M_L的量规函数是一个常数,本文利用近场资料得到了5km内的量规函数,是对GB17740—2017国家标准量规函数在5km内的拓展。本研究所构建的衰减模型及震级测定方法可以推广应用于其他矿区,使矿山地震的震级测定与天然地震的震级测定协调一致。

Abstract:

Mining-induced earthquakes are typically of low magnitude and dominated by high-frequency seismic waves,which can only be effectively recorded by seismic stations located within 5km of the source. To investigate the attenuation characteristics of near-field seismic waves and to develop a local magnitude (M_L) calibration function for the Lilou Coal Mine in Shandong,this study established a three-dimensional seismic observation network comprising 36 surface stations and 33 underground tunnel stations. Seven controlled blasts were conducted to generate high-quality seismic data. The main findings are as follows: (1) Using the near-field seismic records,the S-wave attenuation characteristics within 5km were derived for both surface and underground stations. S-wave attenuation was observed to be particularly rapid within 1km of the source. (2) Calibration functions for M_L were established using both vertical and horizontal components,enabling magnitude estimation in both directions. (3) Applying these calibration functions,the magnitudes of the seven blasts were determined. The results showed strong consistency across various hypocentral distances,with the difference between magnitudes derived from horizontal and vertical components remaining within 0.1. (4) According to the national standard General Ruler for Earthquake Magnitude (GB 17740—2017),the M_L calibration function within 5km is constant. However,this study derived a new calibration function specifically for near-field conditions,thereby extending the applicability of the national standard to mining environments. The attenuation model and magnitude determination method developed here can be applied to other mining regions,enhancing consistency in the magnitude assessment of mining-induced and natural seismic events.