CONTENTS Acknowledgements i Table of Contents iii 1: Introduction 1 1.1Background 1 1.2Landslide hazard and its prediction methods 2 1.2.1 Heuristic and data-driven methods of spatial prediction 3 1.2.2Why are temporal and magnitude predictions difficult? 5 1.3Research objectives 5 1.4Research questions 6 1.5Study area 7 1.5.1. Geology and structure 7 1.5.2Topography and climate 9 1.6Methodology and organisation of thesis 10 2: Evaluating the existing method of landslide susceptibility mapping in India 13 2.1Introduction 13 2.2BIS method of landslide susceptibility mapping 16 2.2.1 Rating and integration of factors 16 2.2.2Validation of BIS landslide susceptibility maps 16 2.3Empirical method of landslide susceptibility mapping 21 2.3.1.Comparison of WofE with LHEF ratings 21 2.3.2.WofE susceptibility maps and validation 24 2.4Predictive capabilities of BIS and WofE methods 26 2.5Conclusions and recommendations 27 3: Generating event-based landslide inventory maps 29 3.1. Introduction 29 3.2Event based landslide inventory maps .31 3.2.1 Source data sets 31 3.2.2 Methods of landslide inventory mapping 32 3.3Analysis of landslide inventories 33 3.4Temporal probability estimation 38 3.4.1 DA modelling for rainfall - landslide event relationships 40 3.4.3 Calculation of exceedance probability 43 3.5Magnitude probability estimation 44 3.5.1 Landslide magnitude-frequency analysis 44 3.5.2 Results and synthesis of magnitude-frequency analysis 44 3.6Discussion 49 3.6.1 Incompleteness and data gaps in source data 49 3.6.2 Limitations in temporal probability estimation 50 3.6.3 Limitations in magnitude probability estimation 52 3.7Conclusions 55 4: Exploratory analysis of fault/ fracture and slope 4.1 Introduction 57 4.2Structures in Himalayan FTB and rock slope failures 58 4.3Spatial patterns of rockslides 60 4.3.1 Fry analysis of point geo-objects 60 4.3.2 Application of Fry analysis for rockslide occurrences 62 4.3.4 Synthesis of Fry analysis on structural and topographic controls on rockslides 68 4.4Spatial association of rockslides with fault/fractures and slope aspects 68 4.4.1 Distance distribution and proportion analysis 68 4.4.2 Spatial association of Sh_rs with faults/fractures and slope aspects 70 4.4.3 Synthesis of spatial association analyses 72 4.5Spatial modelling of mutual fault/fracture and slope controls on rockslides 75 4.5.1 Conceptual framework 75 4.5.2 Evidential belief modelling 77 4.6 Discussion 87 4.7Conclusions 90 5: Rock slope instability analysis using structural orientations 93 5.1Introduction 93 5.2Input data 95 5.2.1 Field-based 3-D orientation data of rock discontinuities 95 5.2.2 Spatially distributed shear strength (o) parameters 99 5.2.3 Digital topographic data . 100 5.3Spatial modelling of structural discontinuity orientations 101 5.3.1 DStM generation in Area A 101 5.3.2 DStM generation in Area B 103 5.4Kinematical testing of rock slope instability 104 5.4.1 Identification of modes of rock slope failure 104 5.4.2 Rock slope instability in Area A 106 5.4.3 Rock slope instability in Area B 108 5.4.4 Evaluation of rock slope instability maps 109 5.5Discussion 111 5.6Conclusions 115 6: Selecting and weighting of spatial factors of landslide susceptibility 117 6.1Introduction 117 6.2Data 119 6.3Analytical methods 123 6.3.1 Spatial association analysis for categorical spatial factors 124 6.3.2 Spatial association analysis for continuous spatial factors 124 6.3.3 Weighting of predictors 126 6.4Predictive models of landslide susceptibility 132 6.4.1 Weighted multi-class index overlay model using pre-selected predictors 132 6.4.2 Logistic regression model using all identified/mapped spatial factors 134 6.4.3 Model evaluation 135 6.5Results 136 6.5.1 Spatial association analysis for categorical spatial factors 136 6.5.2 Spatial association analysis for continuous spatial factors 137 6.5.3 Weighting of spatial factors 139 6.5.4 Predictive modelling of susceptibility 141 6.6Discussion 150 6.6.1 Modelling of predictor-target spatial associations 150 6.6.2 Pairwise modelling of predictor-target relationships 152 6.6.3 Integration of predictors and evaluation of susceptibility maps 153 6.7Conclusions 154 7: Integrating spatial, temporal and magnitude probability for medium-scale landslide hazard and risk estimation 157 7.1Introduction 157 7.2Source data sets and information 158 7.3Landslide hazard and risk estimation methods 160 7.3.1 Prediction of landslide events and hazard scenarios 160 7.3.2 Landslide risk estimation 162 7.4Results of hazard and risk estimation 166 7.4.1 Landslide hazard estimation 166 7.4.2 Landslide risk estimation 167 7.5Discussion and conclusions 173 8: Synthesis and conclusions 177 8.1 Introduction 177 8.2Evaluating the existing method of landslide susceptibility mapping in India 178 8.3Event-based landslide inventory mapping 178 8.4Fault/fracture and slope controls on rocksliding 179 8.5Rock slope stability analysis using structural orientations 180 8.6Selecting and weighting spatial factors of landslide susceptibility 181 8.7Developing quantitative methods for landslide hazard and risk analysis 182 8.8Limitations and future scope of research 183 Summary 205 Samenvatting 209 Curriculum vitae 213 List of Publications 214 ITC Dissertation List 215