## 2 Materials and Methods
### Phase One: Development of Seismic Microzonation Map
#### 2.1.5 Plotting Seismic Microzonation Map  
The last stage in phase one was to plot a seismic microzonation map for each site according to the return period. As discussed earlier, there are five return periods used in this study, consisting of 100-year, 200-year, 500-year, 1000-year, and 2500-year return periods. Seismic microzonation map-plotting was performed by using ArcGIS software. The inverse distance weighted (IDW) tool was used to create the contour of PSa for this study according to the return period. The estimation of a new point was made by averaging the values of data that were close to the processing cell.  
The process of plotting the seismic microzonation map started with creating a new template in ArcMap. Then, a layer of the map was added, which portrayed the map of Malaysia before continuing with adding a Microsoft table in ArcMap as the input data; for this case, input data consisted of coordinates and PSa values. Since the data were in an excel file, the data for the x axis and y axis were imported to ArcMap by using add XY data. A shapefile was created to ease the editing process during data editing. The digitizing process is a process where the boundaries of PSa maps are digitized. The data were created as coordinates in polygon format. Moreover, the coordinate system used was GCS WGS 1984 for the geographic coordinate system. This boundary was used to limit the area where the contour was plotted.  
To create a contour, a model builder was used. The model was the workflow arranged to allow processing of the input data by incorporating geoprocessing tools to produce an output, which then could be used as the input for another tool. In this study, PSa was used as the input, and the contour was created using inverse distance weighted (IDW). IDW is one of the raster interpolation toolset available in Spatial Analyst Tools under geoprocessing. Since IDW uses an interpolation technique, it only can predict the point in the range of the dataset. Plotting of the contour was performed using Contour, one  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{2}{c}{\begin{tabular}{c} **Fundamental Period (s) = 1.04** \\ **Average Shear Wave Velocity (m/sec) = 192.95** \\ **Total Number of Sublayers = 11** \\ \end{tabular} } & \begin{tabular}{c} **Maximum** \\ **Shear** \\ **Layer (m)** \\ **Craye (m)** \\ \end{tabular} & \begin{tabular}{c} **Total Unit** \\ **Shear** \\ **Modulus** \\ **(kN/m3)** \\ \end{tabular} & \begin{tabular}{c} **Shear** \\ **Wave** \\ **Weight** \\ **(kN/m3)** \\ \end{tabular} & \begin{tabular}{c} **Location** \\ **Velocity** \\ **(m/sec)** \\ \end{tabular} & \
\begin{tabular}{c} **Depth at** \\ **Top of** \\ **Table** \\ **Layer (m)** \\ \end{tabular} &
\begin{tabular}{c} **Vertical** \\ **Effective** \\ **Stress (kPa)** \\ \end{tabular} \\ \hline Surface & 1 & 1 & 6.9 & 25.49 & 18.03 & 117.764 & 0.0 & 0.00 \\  & 2 & 1 & 2.9 & 68.58 & 18.03 & 193.169 & 6.9 & 124.41 \\  & 3 & 1 & 5.1 & 48.28 & 18.03 & 162.077 & 9.8 & 176.69 \\  & 4 & 1 & 6.7 & 41.75 & 18.03 & 150.722 & 14.9 & 268.65 \\  & 5 & 1 & 2.4 & 168.40 & 20.73 & 282.296 & 21.6 & 389.45 \\  & 6 & 1 & 3.2 & 85.82 & 19.33 & 208.693 & 24.0 & 439.20 \\  & 7 & 1 & 2.6 & 105.28 & 19.33 & 231.147 & 27.2 & 501.06 \\  & 8 & 1 & 9.1 & 79.37 & 19.33 & 200.705 & 29.8 & 551.31 \\  & 9 & 1 & 5.9 & 76.77 & 18.03 & 204.381 & 38.9 & 727.22 \\  & 10 & 1 & 5.2 & 155.29 & 19.33 & 280.731 & 44.8 & 833.59 \\ Bedrock & 11 & 0 & & 3333.52 & 22.00 & 1219.2 & 50.0 & 934.11 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Worksheet Profile in NERA for D1 site.  
of the raster surface toolsets in Spatial Analyst Tools, available in ArcToolbox or the 3D analyst toolbox.