# Research on Risk Assessment Method for Land Subsidence in Tangshan Based on Vulnerability Zoning
## 3 Hazard Assessment Results for the Study Area
### Evaluation of Ground Subsidence Hazard in the Study Area
#### 3.2.3 Results of Hazard Evaluation in the Study Area  
Drawing on the information value results of the individual evaluation factors and the weights derived from the analytic hierarchy process, the total information values for the study area were calculated by multiplying the two. According to the raster calculation results in ArcGIS, the comprehensive information values range from \(-\)0.808 to 1.028. The natural break method was employed to divide the total information values into four classes, as delineated in Table 21.  
The evaluation results of the ground subsidence hazard in the study area are presented in Figure 23. The central part of the study area exhibits the highest hazard of ground subsidence, which aligns with the occurrence of numerous historical ground subsidence incidents in this region. This can be attributed to a confluence of factors, including severe underground pipeline leakage, karst development, and high traffic volumes on major roads, leading to significant road loads. Conversely, the southern and northeastern parts of the study area exhibit lower hazards of ground subsidence, indicating relatively safer conditions in these areas.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Influencing Factor** & **Classification Index** & **Reclassification** & **N\({}_{\mathbf{i}}\)** & **S\({}_{\mathbf{i}}\) (m\({}^{2}\))** &
\begin{tabular}{c} **Information** \\ **Quantity Value (I\({}_{\mathbf{i}}\))** \\ \end{tabular} \\ \hline \multirow{4}{*}{Road load} & \(>\)15 & 4 & 2495 & 2,245,500 & 1.446575754 \\  & 10–15 & 3 & 48,150 & 43,335,000 & \(-\)0.127162294 \\  & 5–10 & 2 & 104,496 & 94,046,400 & 0.276665048 \\  & 0–5 & 1 & 131,062 & 117,955,800 & \(-\)0.317581433 \\ \hline \multirow{4}{*}{Pipeline leakage} & Goaf area & 2 & 34,378 & 30,940,200 & \(-\)0.483240955 \\  & Non-goaf area & 1 & 251,872 & 226,684,800 & 0.050983492 \\ \hline \multirow{4}{*}{Distance to water} & Serious leakage & 5 & 4380 & 3,942,000 & 0.965842187 \\  & More serious leakage & 4 & 3667 & 3,300,300 & \(-\)0.238577502 \\  & Partial leakage & 3 & 2660 & 2,934,000 & \(-\)1.266627947 \\  & Less leakage & 2 & 37,320 & 33,588,000 & 0.159987053 \\  & Basically no leakage & 1 & 215,071 & 193,563,900 & 0.215478965 \\ \hline \multirow{4}{*}{Distance to water} & 0–100 m & 4 & 24,109 & 21,698,100 & \(-\)0.821629891 \\  & 100–200 m & 3 & 22,431 & 20,187,900 & \(-\)0.056341426 \\  & 200–300 m & 2 & 21,230 & 19,107,000 & 0 \\  & \(>\)400 m & 1 & 218,459 & 196,613,100 & 0.1524108 \\ \hline \multirow{4}{*}{Rainfall} & \(>\)230 mm & 4 & 57,759 & 51,983,100 & \(-\)0.596519434 \\  & 210–230 mm & 3 & 72,858 & 65,572,200 & 0.84522384 \\  & 180–210 mm & 2 & 79,152 & 71,236,800 & \(-\)0.218463126 \\  & \(<\)180 mm & 1 & 76,515 & 68,863,500 & \(-\)1.28319216 \\ \hline \multirow{2}{*}{Earthquake acceleration} & 0.3 g & 2 & 188,356 & 169,520,400 & 0.30066139 \\  & 0.20 g & 1 & 97,869 & 88,082,100 & \(-\)1.124076212 \\ \hline \multirow{2}{*}{Seismic liquefaction} & Liquefaction zone & 2 & 26,311 & 23,679,900 & \(-\)0.909049248 \\  & Non-liquefied region & 1 & 259,913 & 233,921,700 & 0.058687433 \\ \hline \hline \end{tabular}
\end{table}
Table 20: _Cont._