# 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  
#### 3.2.1 Weight Calculation for Evaluation Indicators  
Drawing upon the evaluation indicator system for the ground subsidence hazard in the study area and the classification results of each indicator, the analytic hierarchy process-information value evaluation model was employed to compute the information value of individual evaluation factor. Subsequently, the weight of each single factor was ascertained through the amalgamation of the analytic hierarchy process and information value method, culminating in the final evaluation of the hazard in the study area, as delineated in Tables 15-19. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Influencing Factor** & **Geological Condition** &
\begin{tabular}{c} **Engineering** \\ **Condition** \\ \end{tabular} & **Inducing Factor** & **Eigenvector** & **Weight** \\ \hline Geological condition & 1 & 1/2 & 1/2 & 0.333 & 0.2 \\ Engineering condition & 2 & 1 & 1 & 0.667 & 0.4 \\ Inducing factor & 2 & 1 & 1 & 0.667 & 0.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 15: Judgment matrix of criterion layer-target layer. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Dynamic Peak Values of Earthquake Acceleration** & **Value** \\ \hline
0.20 g & 1 \\
0.30 g & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 14: Earthquake acceleration values of the study area. Figure 22: Earthquake acceleration of the study area. (**a**) Distribution of earthquake acceleration (**b**) Classification of earthquake acceleration. The consistency requirement is satisfied for all the judgment matrices, as indicated by the matrix calculation results. We know from the matrix calculation results that \(\lambda_{\text{max}}=4.0145,RI=0.90\). \[CI=(\lambda_{\text{max}}-n)/(n-1)=(4.0145-4)/3=0.0462\] \[CR=CI/RI=0.0462/0.90=0.0516<0.1\] \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Influencing Factor** & **Stratigraphic** & **Geological** & **Quaternary** & **Distance to** & **Eigenvector** & **Weight** \\ \hline Stratigraphic & 1 & 1/2 & 1/3 & 2 & 0.2694 & 0.157 \\ lithology & & & & & & \\ Geological & 2 & 1 & 1/2 & 3 & 0.4667 & 0.272 \\ structure & & & & & & \\ Quaternary & 3 & 2 & 1 & 5 & 0.8287 & 0.481 \\ groundwater & & & & & & \\ Distance to water & 1/2 & 1/3 & 1/5 & 1 & 0.1513 & 0.090 \\ \hline \hline \end{tabular}
\end{table} 
Table 16: Judgment matrix of index layer–natural-factor criterion layer. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Influencing Factor** & **Rainfall** & **Pipeline** & **Seismic** & **Earthquake** & **Eigenvector** & **Weight** \\ \hline Rainfall action & 1 & 1/2 & 2 & 3 & 0.4667 & 0.272 \\ Pipeline leakage & 2 & 1 & 3 & 5 & 0.8287 & 0.482 \\ Seismic liquefaction & 1/2 & 1/3 & 1 & 2 & 0.2694 & 0.157 \\ Earthquake acceleration & 1/3 & 1/5 & 1/2 & 1 & 0.1513 & 0.089 \\ \hline \hline \end{tabular}
\end{table} 
Table 18: Judgment matrix of indicator layer–inducing-factor criterion layer. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Influencing Factor** & **Geological Condition** & **Engineering Condition** & **Inducing Factor** & **Factor Weight** \\ \cline{2-5}  & **0.2** & **0.4** & **0.4** & **Factor Weight** \\ \hline Stratigraphic Lithology & 0.157 & 0 & 0 & 0.0314 \\ Geological structure & 0.272 & 0 & 0 & 0.0544 \\ Quaternary groundwater & 0.481 & 0 & 0 & 0.0962 \\ Distance to water & 0.090 & 0 & 0 & 0.018 \\ Road load & 0 & 0.234 & 0 & 0.0936 \\ subsidence area & 0 & 0.448 & 0 & 0.1792 \\ Goat area & 0 & 0.234 & 0 & 0.0936 \\ Road network density & 0 & 0.084 & 0 & 0.0336 \\ Rainfall action & 0 & 0 & 0.272 & 0.1088 \\ Pipeline leakage & 0 & 0 & 0.482 & 0.1928 \\ Seismic liquefaction & 0 & 0 & 0.157 & 0.0628 \\ Earthquake acceleration & 0 & 0 & 0.089 & 0.0356 \\ \hline \hline \end{tabular}
\end{table} 
Table 19: Weight distribution of evaluation factors.