## 4 Results and Discussion
### Community Detection  
In the present study, a community detection method based on random walk strategy is utilized to extract communities from the developed interaction network of seafarers' unsafe acts and their influencing factors, and to comprehensively explore the risk propagation patterns from a multidimensional perspective. In order to obtain a higher modularity value, after several trails, the modularity value (0.3631) is maximum and greater than 0.3 when the step length \(t\) of random walk is set to 4, which indicates that the community detection has obtained a good community structure. As shown in Figure 10, the interaction network of seafarers' unsafe acts and their influencing factors is divided into five communities, and it should be noted that there are adjacent nodes between communities, which means that there is still the possibility of risk propagation between different communities, but their risk interactions are sparser compared with those within communities. To further explore the risk propagation patterns in the interaction network, this study conducts specific analysis for each of the five communities. Community 1 includes 10 nodes of insufficient maintenance (S5), cargo defect (S7), lack of safety awareness (P10), device failure (E1), flooding (E2), strong wind and waves (E6), failure to use protective equipment (U2), failure to perform safety duties during berthing (U6), violation of operational procedures (U9), and improper emergency response measures (U20). The community involves four typical risk propagation paths of seafarers' unsafe acts, as shown in Figure 11. The colored arrows refer to typical risk propagation paths. (1) Due to improper daily inspection and maintenance of the ship, sudden failure of device (rudder, main engine, etc.) during navigation operations, as well as poor safety awareness of the seafarers, etc., resulting in untimely and inappropriate emergency response measures, which eventually lead to ship accidents; (2) Under the effect of strong wind and waves, as well as ship's being empty, fully loaded, overloaded and improperly cargo loaded. The ship deck is on the waves, and water enters inside the cabin, due to the seafarers' poor safety awareness and other reasons. The seafarer goes to the main deck for side cabin operation without using safety ropes, wearing life jackets and other appropriate protective measures, and the emergency response measures are improper, which eventually have  
Figure 10: Community detection results of the network. a greater possibility of leading to the personnel falling into the water and ship sinking accidents; (3) When the ship moored at berth, under the effect of strong wind and waves, the ship position is uncontrolled and may be dragging anchor, meanwhile, the seafers do not fully perform the safety duties of berthing watch and make routine inspection of the ship, the seafarers fail to discover the current danger in time and do not take any emergency measures which may eventually lead to ship accidents; (4) Due to improper daily inspection and maintenance of the ship, as well as the weak safety awareness of the seafarers, the seafarers violate the operation procedures when carrying out fire operation, which tends to cause fire and explosion accidents. Community 2 includes 21 nodes such as lack of standardization (O7), complex navigation environment (E3), busy traffic (E4), poor visibility (E5). The community involves the largest number of nodes, mainly including three risk propagation paths of seafarers' unsafe acts, and has typical collision accident characteristics, as shown in Figure 12. The colored arrows refer to typical risk propagation paths.