# A Combined Method for Preparation of Landslide Susceptibility Map in Izmir (Turkije)
## 4 Results and Discussion
### Comparison of LSM Results
of**} & \multicolumn{1}{c}{**Percentageof**} & \multicolumn{1}{c}{**FR**} & \multicolumn{1}{c}{**Normalized**} \\  & & **in Domain** & **of Domain** & **Landside** & **Landside** & **FR** & **Frequency Ratio** \\ \hline \multirow{9}{*}{Slope (Deg)} & 0–10 & 1,527,794 & 60.43 & 14,109 & 32.72 & 0.54 & 0.31 \\  & 10–20 & 678,851 & 26.85 & 19,454 & 45.12 & 1.68 & 0.95 \\  & 20–30 & 266,839 & 10.55 & 7966 & 18.47 & 1.75 & 0.99 \\  & 30–40 & 49,548 & 1.96 & 1491 & 3.46 & 1.76 & 1.00 \\  & \(>\)40 & 5163 & 0.20 & 100 & 0.23 & 1.14 & 0.65 \\ \hline \multirow{9}{*}{Aspect} & Flat & 29,326 & 1.16 & 0 & 0.00 & 0.00 & 0.00 \\  & N & 312,627 & 12.37 & 3910 & 9.07 & 0.73 & 0.42 \\  & NE & 259,456 & 10.26 & 2174 & 5.04 & 0.49 & 0.28 \\  & E & 247,899 & 9.81 & 5175 & 12.00 & 1.22 & 0.70 \\  & SE & 299,619 & 11.85 & 7315 & 16.96 & 1.43 & 0.82 \\  & S & 338,804 & 13.40 & 10,140 & 23.52 & 1.75 & 1.00 \\  & SW & 330,225 & 13.06 & 5856 & 13.58 & 1.04 & 0.59 \\  & W & 343,688 & 13.59 & 4858 & 11.27 & 0.83 & 0.47 \\  & NW & 366,551 & 14.50 & 3692 & 8.56 & 0.59 & 0.34 \\ \hline \multirow{9}{*}{SPI} & Low & 434,163 & 17.17 & 4457 & 10.34 & 0.60 & 0.37 \\  & Moderate & 667,197 & 26.39 & 3997 & 9.27 & 0.35 & 0.21 \\  & High & 1,145,730 & 45.32 & 26,856 & 62.28 & 1.37 & 0.84 \\  & Ex. high & 281,105 & 11.12 & 7810 & 18.11 & 1.63 & 1.00 \\ \hline \multirow{9}{*}{Distance} & 0–100 & 628,808 & 24.87 & 8536 & 19.80 & 0.80 & 0.62 \\  & 100–200 & 536,113 & 21.21 & 8353 & 19.37 & 0.91 & 0.70 \\  & from stream & 200–300 & 450,044 & 17.80 & 7591 & 17.60 & 0.99 & 0.77 \\ (m) & 300–400 & 377,276 & 14.92 & 6863 & 15.92 & 1.07 & 0.83 \\  & \(>\)400 & 535,954 & 21.20 & 11,777 & 27.31 & 1.29 & 1.00 \\ \hline \multirow{9}{*}{Density of discontinuity} & Low & 803,727 & 31.79 & 2925 & 6.78 & 0.21 & 0.11 \\  & Moderate & 766,508 & 30.32 & 14,173 & 32.87 & 1.08 & 0.56 \\  & High & 720,240 & 28.49 & 18236 & 42.29 & 1.48 & 0.77 \\  & Ex. high & 237,720 & 9.40 & 7786 & 18.06 & 1.92 & 1.00 \\ \hline \multirow{9}{*}{Curvature} & Convex & 367,398 & 14.53 & 9300 & 21.57 & 1.48 & 1.00 \\  & Plain & 1,773,818 & 70.16 & 25,822 & 59.88 & 0.85 & 0.57 \\  & Concave & 386,979 & 15.31 & 7998 & 18.55 & 1.21 & 0.82 \\ \hline \multirow{9}{*}{Lithology} & Qalv & 750,212 & 29.71 & 213 & 0.49 & 0.02 & 0.00 \\  & Vlr & 362,782 & 14.37 & 15,952 & 36.99 & 2.57 & 1.00 \\  & Lms & 201,654 & 7.99 & 4715 & 10.93 & 1.37 & 0.53 \\  & Qsv & 7848 & 0.31 & 0 & 0.00 & 0.00 & 0.00 \\  & SnSh & 688,762 & 27.28 & 11,822 & 27.42 & 1.00 & 0.39 \\  & Vsd & 9260 & 0.37 & 0 & 0.00 & 0.00 & 0.00 \\  & Plc & 30,337 & 1.20 & 0 & 0.00 & 0.00 & 0.00 \\  & Dcr & 429,522 & 17.01 & 10,267 & 23.81 & 1.40 & 0.55 \\  & Srp & 21,359 & 0.85 & 120 & 0.28 & 0.33 & 0.13 \\  
The LSM produced by the IOE method was classified using the natural breaks method and divided into five classes, from extremely low to extremely high. IOE values for causative factors are given in Table 6. The LSM prepared with IOE method is given in Figure 10.  
In order to finalize the mapping, the abovementioned analysis results were overlaid on a pixel basis, and the LSMs produced by the LR, AHP, FR and IOE methods were combined with the help of ArcMap software's [95] Spatial Analyst Tools. The susceptibility map produced by the combined method was reclassified into five classes, from extremely low to extremely high, using the natural breaks method (Figure 11). A graph showing the percentages of susceptibility classes in the landslide inventory map and susceptibility classes in the study area is given in Figure 12.  
It was determined that in the LSM prepared using LR method, the existing landslide areas' susceptibility classes were: 2.07%--extremely low, 8.84%--low, 28.82%--moderate, 25.57%--high and 34.7%--extremely high. The AHP-based LSM showed landslide susceptibilities classes of 0.19%--extremely low, 6.27--ow, 12.01%--moderate, 36.7%--high and 44.84%--extremely high. For the FR method, the values were found to be 0.18%--extremely low, 2.72%--low, 10.93%--moderate, 31.88%--high and 54.29%--extremely high.