| Value | Category | Cases | |
|---|---|---|---|
| -1 | Missing | 0 | 
                                    
                                    0%
                                 | 
| 1 | Human Activity | 571 | 
                                    
                                    23.8%
                                 | 
| 2 | Natural processes | 378 | 
                                    
                                    15.8%
                                 | 
| 3 | Both human activity and natural processes | 305 | 
                                    
                                    12.7%
                                 | 
| 4 | None of these | 4 | 
                                    
                                    0.2%
                                 | 
| 7 | Not applicable | 1024 | 
                                    
                                    42.7%
                                 | 
| 8 | Refused | 2 | 
                                    
                                    0.1%
                                 | 
| 9 | Don’t know / Haven’t heard enough | 116 | 
                                    
                                    4.8%
                                 |