Earthquake-Induced Rock Fall Hazard Zonation of Varzeghan-Ahar Region in Northwest Iran: AComparison of Quantitative and Qualitative Approaches

In this study, three earthquake-induced rock fall hazard maps of the regions affected by Varzeghan-Ahar earthquake doublet are presented. On August 11, 2012 an earthquake doublet (Mw= 6.5 and, Mw= 6.3) struck Varzeghan, Ahar and Heris regions (located in Azerbaijan-e-Sharghi province of Iran). Most of the landslides triggered by the earthquakes were rock falls and disrupted rock slides. Several rock fall zones, some with more than 150 rock falls were recorded, the farthest one approximately 45 kilometers away from the earthquake epicenters. A landslide inventory map of the region was prepared using field survey gathered data and satellite imagery analysis. Three methods of Information Value (IV), Logistic Regression (LR), and Analytical Hierarchy Process (AHP) were used for earthquake- induced rock fall hazard zonation. LR and IV are quantitative landslide hazard zonationmethods, and AHP is a qualitative one. The results fromeachmethod were then compared using Receiver Operating Characteristics (ROC) curve. The area under ROC curve (AUC) was 0.927, 0.90, and 0.898 for LR, IV, and, AHP models, respectively. LR seems to be the most suitablemethod for the study, although all three methods have approximately similar qualities.