基于L形单分量检波器组合台站的微地震震源精定位方法

Locating microseismic sources based upon L-shaped single-component geophone array:A synthetic study

本文研究了基于L形单分量检波器组合作为单个地震观测台时的微地震震源定位方法。首先,介绍方法的实施过程,包括利用两条相互正交的单分量检波器线性排列组合作为单个台站采集连续地震资料,利用速度扫描方法分析两正交检波器排列中直达P波视速度,根据近地表速度进一步求解直达P波的出射矢量及利用逆时射线追踪震源定位方法求解微地震震源位置。然后,基于数值模拟研究L型检波器台站观测下微地震震源精定位方法的准确性及精度高,结果表明可准确获取各台站直达P波射线矢量并精准确定震源位置。最后,分析了噪声对定位结果的影响,结果表明,噪声下仍可有效获取检波器排列的直达P波射线矢量,对定位结果影响小。

We have developed a type of L-shaped single-component geophone array as a single station(L-array station)for surface microseismic monitoring.The L-array station consists of two orthogonal sensor arrays,each being a linear array of single-component sensors.L-array stations can be used to accurately estimate the polarization of first arrivals without amplitude picking.In a synthetic example,we first use segmentally iterative ray tracing(SIRT)method and forward model to calculate the travel time and polarization of first arrivals at a set of L-array stations.Then,for each L-array station,the relative delay times of first arrivals along sensor arrays are used to estimate the polarization vector.The small errors in estimated polarization vectors show the reliability and robustness of polarization estimation based on L-array stations.We then use reverse-time ray-tracing(RTRT)method to locate the source position based on estimated polarizations at a set of L-array stations.Very small errors in inverted source location and origin time indicate the great potential of L-array stations for source localization applications in surface microseismic monitoring.