Journal Article

Source types of induced earthquakes in underground mines: Revealed by regional moment tensor inversion

Qu, Junhao, Li, Bo, Zhang, Zhihui, Liu, Chengyu, Li, Guoyi, Liu, Fangbin, Li, Zhiheng

2024

Overview

Mining-induced earthquakes have been very frequent in recent years due to increasing mechanized mining. Compared with natural earthquakes, even a small one may cause significant damage to the mine area and its surroundings. Source type identification is important for better understanding the physical processes and is a crucial and fundamental issue for hazard assessment and emergency rescue in the mining environment. The moment tensor (MT) theory plays a pivotal role in distinguishing different source types. In this study, we concentrated on two strong reported “mine collapse earthquakes” in Qufu (M L 3.2, July 13, 2020) and Zoucheng (M L 2.9, June 09, 2020), Shandong Province, China. Seismograms from regional seismic stations were utilized to calculate the full moment tensors through low-frequency full-waveform inversion. Our results show that the two studied events exhibit notably different source types. The DC (Double-Couple) component of both events are 5% (Qufu) and 60% (Zoucheng), respectively. The Qufu event which contains approximately 75% closing crack component, is more consistent with the theoretical models of collapse seismic source. However, the Zoucheng event, which exhibits a significant proportion of DC components, demonstrates characteristics typical of shear failure. Focusing on the Zoucheng event, which occurred at the Dongtan Coal Mine, further research was conducted on a local mining scale. Analyzed in conjunction with microseismic sensor data, geologic setting, and mining progress, we illustrated that the source type of Zoucheng event is not a collapse one. The fracture slip of a thick-hard roof due to an overlying load, characterized by a large DC component, is a plausible geomechanical interpretation. Article Highlights Distinguishing between different source types is key to understanding their physical processes and evaluating hazard. We employed the method of regional moment tensor inversion to analyze the source types and mechanisms for the Qufu and the Zoucheng events. The Zoucheng event was further researched at a local mining scale, analyzing microseismic sensor data in conjunction with the geological setting and mining progress.

• Publisher: Springer International Publishing,Springer
• Subject: DC component / Energy / Engineering / Environmental Science and Engineering / Foundations / Geoengineering / Geomechanical challenges in the process of comprehensive utilization of closed/abandoned mines / Geophysics/Geodesy / Geotechnical Engineering & Applied Earth Sciences / Hydraulics / Mining-induced earthquakes / Moment tensor inversion / Source types