# GIS-Analysis for Active Tectonics Assessment of Wadi Al-Arish, Egypt
## 4 Results and Discussion
### Relative Tectonic Activity Levels Discussion  
The application of morpho-tectonic indices along continental-scale features has been discussed in many studies [6; 57; 63; 69; 70]. Various analyses have been applied to the relationship between two morphometric indices (Smf and Vf) to present a primary quantitative model of the levels of tectonic activity of mountain fronts. Combining these two indices indicates tectonic activity classes [1; 6; 62; 63; 66]. Accordingly, some researchers have modeled a relationship between Smf and Vf values showing the distribution of these values along main rivers and streams, and along front segments [5; 63; 66]. In our research, we calculated morpho-tectonic indices for better landscape evaluations regarding tectonic activity levels. Generally, the indices have been classified by relative tectonic signals detected over the entire catchment [6; 7; 63; 67; 69]. In the present study, we applied the method of [6] that evaluates each index of a particular class of activity to model the relative tectonic activity classes of the Wadi Al-Arish catchment. To check the validity of our method, we probed many recent works. Relative tectonic classes were investigated along the southwest border of the Sierra Nevada in southern Spain by the authors of [6]. The boundaries of the studied levels changed with a single index; thus, for the purpose of this study, the boundaries selected were generally matched with changes in the various index value ranges. In this study, we t focused only on areal features (catchments and sub/catchments) and averaged the results from the same bodies or features. In addition, many researchers (e.g., [9; 70]) state that studying catchments may indicate uplift and subsidence signals and rates, and the origin of seismicity. The calculated indices were arbitrarily classified into three classes: high tectonic activity expressed (class 1), moderate tectonic activity named (class 2), and low tectonic activity (class 3). In this study, a new major average index (A/L) was defined as the relative tectonic activity level (RTAL) and estimated for all studied indices with four levels: level 1 defining very high tectonic activity signals (A/L between 1 and 1.5); level 2 with high tectonic activity signals (2 \(\geq\) A/L > 1.5); level 3 with moderately active tectonics signals (2.5 \(\geq\) A/L > 2), and level 4 with low tectonic activity signals (A/L > 2.5) (Table 1). The  
Figure 8: Map of mountain front sinuosity (Smf) locations and 83 mountain front segments for the Smf index. average indices of A/L and values of RTAL are shown in Table 1 for 146 catchments/sub-catchments of Wadi Al-Arish (check Figure 4 for catchments/sub-catchments positions and locations). The Wadi Al-Arish catchment was investigated using morpho-tectonic indices for the first time, and low tectonic activity signals covered the largest parts of the study catchment. The tectonic analysis show that the high values (low tectonic signals) for the RTAL were  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Catch. ** & **A/L** & **RTAL** & **Catch. ** & **A/L** & **RTAL** & **Sub-C.** & **A/L** & **RTAL** \\ \hline
1  
observed in the north to northwest parts of Wadi Al-Arish region. Additionally, some of these signals were recorded in the south and northeast parts asw well. Moderate tectonic levels were found mainly in the northeast part of the study region with some signals in the south and middle parts. The RTAL index indicated high tectonic activity varying from large occurrences to small in the northeast, south, southeast, and north, respectively. High tectonic activity signals were recorded only in a very small part along the Ragabet El-Naam Shear zone.