## 2 Research on Visualization of Landslide Monitoring Literature
### Keyword Analysis  
By analyzing keywords of the literature, the hotspots of landslide monitoring in current research can be displayed clearly. In the quantitative analysis of keywords, the minimum frequency of keyword occurrence was set to 20, and 155 eligible keywords were obtained. The top 10 keywords with the highest degree of association are shown in Table 1. Among them, total link strength refers to the total number of co-occurrence times of a keyword with other keywords, including the number of repeated co-occurrence times. Presently, VOSviewer 1.6.19 ([[https://www.vosviewer.com/download](https://www.vosviewer.com/download)]([https://www.vosviewer.com/download](https://www.vosviewer.com/download)) (accessed on 14 July 2024)) is a widely used bibliometric analysis software in the study of development trends in various fields [15; 16; 17], that enables visual analysis of a vast array of studies by utilizing keywords, titles, publication years, and other relevant information. By using VOSviewer, the high-frequency keywords in 2470 articles were visualized, and a visual correlation map (Figure 5) was obtained. It clearly shows the correlation between the various influencing factors of landslides. Through the high-frequency keyword analysis, key factors affecting the occurrence of landslide hazards can be concluded. Monitoring, early warning, and preventing landslide hazards have received widespread attention from society. The occurrence of landslides is often influenced by multi-field coupling effects such as rainfall seepage, slope deformation under earthquake action, and stress imbalance under engineering disturbance. In addition, there is a strong correlation between multi-dimensional \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Number** & **Keyword** & **Occurrences** & **Total Link Strength** \\ \hline
1 & Landslide & 715 & 3259 \\ \hline
2 & Deformation & 274 & 1563 \\ \hline
3 & Model & 273 & 1450 \\ \hline
4 & Rainfall & 234 & 1332 \\ \hline
5 & Failure & 198 & 1132 \\ \hline
6 & Monitoring & 202 & 1111 \\ \hline
7 & InSAR & 169 & 1076 \\ \hline
8 & Stability & 164 & 882 \\ \hline
9 & Prediction & 124 & 702 \\ \hline
10 & Interferometry & 124 & 676 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: High-frequency keyword statistics. Figure 4: Annual publication statistics of landslide monitoring technology. landslide monitoring technologies in space, sky, ground, and underground, indicating that multi-dimensional monitoring technologies will play an increasingly important role in the early warning and prevention of landslide hazards in the future. To further analyze the hotspots of landslide monitoring methods, the monitoring technologies involved in the above 2470 articles were analyzed and the top 5 landslide monitoring technologies with the highest frequency of occurrence as well as their annual changes are presented in Figure 6.  
It can be concluded that the most frequent monitoring technology for landslides is GNSS (Global Navigation Satellite System), which consists of GPS (Global Positioning System), GLONASS (Global Navigation Satellite System), BDS (Beidou Navigation Satellite System), and Galileo (Galileo Satellite Navigation System). GNSS can conduct all-weather  
Figure 5: Keyword association analysis graph for landslide monitoring technology. Figure 6: Analysis of popular technologies for landslide monitoring. real-time monitoring of the entire landslide and makes it easy to grasp the overall deformation status of the slope from a macro perspective, thus achieving precise control of the overall condition of the landslide [18]. In addition, as an emerging technology, the InSAR technology included in the 3S technology has the advantage of large-scale and all-weather monitoring, which is especially prominent in landslide deformation monitoring and has become one of the most practical and effective technologies in the field of landslide monitoring [19]. The third most frequently occurring monitoring technology is GIS (Geographic Information System).