# Study on Microseismic Monitoring of Landslide Induced by Blasting Caving
## 4 Microseismic Monitoring Analysis of Landslide
### Microseismic Moment Tensor Analysis for Types of Mountain Body Slide  
By applying moment tensor theory [28; 29] to the microseismic events monitored during this mountain body slide, the source mechanism is inverted. The moment tensors of the monitored microseismic events are computed and decomposed. Using the moment tensor rupture criteria proposed by [PERSON] and [PERSON] [30], the types of internal rock mass failure prior to the mountain body slide are determined. \[R=\frac{tr(M)}{|tr(M)|+\sum\lvert m_{i}^{*}\rvert}\times 100\]  
In this equation: R is the ratio of the volumetric component to the shear component, \(tr(M)\) is the trace of the moment tensor, and m\({}_{i}^{*}\) are the eigenvalues of the deviatoric tensor, m\({}_{i}^{*}=M_{\text{i}}-tr(M)/3\). Depending on the value of RR, the following criteria apply:  
\[R>30\qquad\text{(The seismic source is dominated by tensile rupture)} \tag{7}\] \[-30\leq R\leq 30\quad\text{(The seismic source is dominated by shear rupture)}\] \[R<-30\qquad\text{(The seismic source is dominated by compaction rupture)}\]  
This section focuses on the processing of 39 microseismic location events with concentrated source distributions in the area of mountain body failure. Based on energy levels and proximity to the landslide position, these events are uniformly numbered from Event 1 to Event 39 (from top to bottom). Specific data processing is conducted by solving the moment tensor using the maximum P-wave amplitude of each monitored microseismic event to invert the source mechanism. The coordinate parameters of the 39 extracted microseismic location events are detailed in Table 4. According to the moment tensor theory and source mechanism inversion method, the final R values of the 39 microseismic events are presented in Table 4. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
\begin{tabular}{c} **Event** \\ **Number** \\ \end{tabular} & **North/m** & **East/m** & **Depth/m** & **Event** & **North/m** & **East/m** & **Depth/m** \\ \hline  
& & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Microseismic event data for moment tensor analysis. Based on the distribution of R values (see in Table 5) calculated from the moment tensor solutions of the 39 microseismic location events in Table 4, 20 events exhibit R values within the range of [-30, 30]. According to the corresponding criteria, these events correspond to shear rupture, accounting for 51%. Further analysis of the tabulated data reveals that a significant portion of the R values associated with tensile or compaction rupture are close to the critical threshold for classification (Events 1, 4, 8, 9, 11, 13, 17, 20, 21, and 36). Therefore, based on the R values, the type of mountain body slide failure induced by the large-scale blasting is most likely to be shear-dominated. By integrating the event numbering sequence in Table 4 with the spatial coordinates of the microseismic events, it is evident that in the upper portion (700-755 m) of the failed mass, no clear dominance of any single failure type is observed, with all three types (tensile, shear, and compaction) coexisting. In contrast, the lower portion (645-700 m) predominantly exhibits shear rupture as indicated by the R values. This pattern of complex failure types in the upper region and predominantly shear rupture in the lower region is consistent with the observed macroscopic failure behavior. Field investigations indicate that blasting-induced failure resulted in the formation of a hanging wall structure in the upper region, with an area exceeding 20,000 m\({}^{2}\). A well-developed fault was identified within the hanging wall rock mass, with a measured dip direction of 327\({}^{\circ}\) and a dip angle of 76\({}^{\circ}\). The hanging wall rock mass underwent massive sliding along this fault, forming a relatively smooth sliding surface, which is characteristic of shear failure. The total volume of the landslide rock mass induced by blasting is approximately 4.47 million m\({}^{3}\), as shown in Figure 19.