Assessment of shallow seated landslide size and magnitude characteristics: An example from Northeastern Turkey

Landslides occurred in the Northeastern part of Turkey are generally classified to be shallow seated landslides or earthflow type based on Varnes (1984) classification. These landslides are occasionally seen in the weathered  Eocene or Upper Crateceous aged volcanic and volcano-clastic rocks. Although there are considerable studies both directly on these landslides in point of mapping and hazard assessment, there is no any studies concerning size and magnitude characteristics of them. By considering this point, an assessment of size and magnitude characteristics of shallow seated type landslides at an area where is one of most landslide prone area of Turkey was carried out.

The investigation area is totaly covered by Eocene aged volcano-clastic lithology, and the weathering is widespread due to the climatical conditions in the area. The extend of the area is 140 square kilometers. In the area, 120 landslides were mapped by a multiple image interpretation that is from the years of 2000 to 2019. To do this, Google Earth images were used. In the area, the area (A_L) of the landslide mapped differs from 53.28 m² to 902,809 m². The length and width of these landslide were also determined and these characteristics were taken into account for an assessment of relationship between the size and topographical features such as slope gradient, curvature, topographical wetness index and stream power index. The approximate volumes of these landslides were calculated by considering direct depth observations in the field surveys, and then assessed by different relations proposed by different studies. Magnitude (M) of these landslides were also assessed by taken into account of the area (A_L) and volume (V_L) values.