Targeted location of microseismic events based on a 3D heterogeneous velocity model in underground mining

Liguan Wang,Pingan Peng,Peitao Wang

doi:10.1371/journal.pone.0212881

Abstract

The accurate location of induced seismicity is a problem of major interest in the safety monitoring of underground mines. Complexities in the seismic velocity structure, particularly changes in velocity caused by the progression of mining excavations, can cause systematic event mislocations. To address this problem, we present a novel construction method for an arbitrary 3D velocity model and a targeted hypocenter determination method based on this velocity model in underground mining. The method constructs a velocity model from 3D geological objects that can accurately express the interfaces of geologic units. Based on this model, the block corresponding to the minimum difference between the observed arrival times and the theoretical arrival times computed by the Fast Marching Method is located. Finally, a relocation procedure is carried out within the targeted block by heuristic algorithms to improve the performance. The accuracy and efficiency of the proposed method are demonstrated by the source localization results of both synthetic data and on-site data from Dongguashan Copper Mine. The results show that our proposed method significantly improves the location accuracy compared with the widely used Simplex and Particle Swarm Optimization methods.

Highlights

Microseismic monitoring is becoming a common tool with wide and successful applications in mining engineering [1]
Boltz et al [27] discussed the influence of a mining-induced low-velocity zone (LVZ) on the locations of coal mining-induced seismicity and suggested that the location accuracy was greatly improved by considering the LVZ
These methods focus on specific velocity models or specific applications, which restrict the usage of these methods to more general applications

Summary

Introduction

Microseismic monitoring is becoming a common tool with wide and successful applications in mining engineering [1]. Grigoli et al [18] presented a modified version of the SSA and demonstrated an application to mining-induced seismicity, and Gharti et al [19] suggested a similar method Using both rotation and stacking, the signal-to-noise ratio is enhanced, and the hypocenter is located through a robust global search algorithm. Boltz et al [27] discussed the influence of a mining-induced low-velocity zone (LVZ) on the locations of coal mining-induced seismicity and suggested that the location accuracy was greatly improved by considering the LVZ These methods focus on specific velocity models or specific applications, which restrict the usage of these methods to more general applications. We validate the method with two synthetic examples and a field application in underground mines

Methodology

Method

Findings

Conclusion