Grant Agreement No.: 226479 SafeLand Living with landslide risk in Europe: Assessment, effects of global change, and risk management strategies 7th Framework Programme Cooperation Theme 6 Environment (including climate change) Sub-Activity 6.1.3 Natural Hazards Deliverable D2.4 Guidelines for landslide susceptibility, hazard and risk assessment and zoning WP 2.1: Harmonisation and development of procedures for quantifying landslide hazard Deliverable/Work Package Leader: UPC Revision: 3 – Final April 2011 Rev. Deliverable Responsible Controlled by Date 0 UPC 1 2 Guidelines for landslide susceptibility, hazard and risk zoning SUMMARY The aim of this document is the recommendation of methodologies that can be used for the quantitative assessment of the landslide hazard, vulnerability and risk at different scales (site specific, local, regional and national), as well as for the verification and validation of the results. The included methodologies mainly focus on the evaluation of the probability of occurrence of different landslide types with certain characteristic, the assessment of the elements at risk (persons, buildings, infrastructures...), the potential degree of damage and the quantification of the vulnerability of the latter and the quantitative risk assessment (QRA). The present document is addressed to scientists and practicioner engineers, geologists and other landslide experts. Note about contributors The following organisations contributed to the work described in this deliverable: Lead partner responsible for the deliverable: Technical University of Catalonia (UPC) Deliverable prepared by: Jordi Corominas Olga-Christina Mavrouli Partner responsible for quality control: Bureau des Recherches Géologiques et Minières (BRGM) Hormoz Modaressi Contributors: International Center for Geohazards (ICG) Farrokh Nadim Bjørn Vidar Vangelsten Università degli studi di Salerno (Unisa) Leonardo Cascini Settimio Ferlisi Aristotle University of Thessaloniki (AUTH) Stravoula Fotopoulou Kyriazis Pitilakis Eidgenössische Technische Hochsschule Zürich (ETHZ) Harikrishna Narasimhan Michael H. Faber 2 Guidelines for landslide susceptibility, hazard and risk zoning Università degli studi di Firenze (Unifi) Filippo Catani Veronica Tofani Joint Research Centre (JRC) Miet Van Den Eeckhaut Javier Hervás Fundación Agustín de Betancourt (FUNAB) Manuel Pastor Universitá degli Studi di Milano- Bicocca (UNIMIB) Paolo Frattini Federico Agliardi Faculty of Geo-information Sciences and Earth Observation (ITC), University of Twente Cees van Westen Centre National de la Recherche Scientifique (CNRS) Jean-Philippe Malet Transport Research Laboratory (UK) Jessica T. Smith Mike G. Winter 3 Guidelines for landslide susceptibility, hazard and risk zoning TABLE OF CONTENTS 1 Foreword ........................................................................................ 11 References ........................................................................................... 13 2 Definitions and terminology ......................................................... 15 References ........................................................................................... 20 3 QRA framework ............................................................................ 21 3.1 Framework for multi-hazard landslide risk assessment ...................... 22 References..................................................................................................... 25 4 Landslide zoning at different scales ............................................ 26 4.1. Introduction ......................................................................................... 26 4.2. Purpose of landslide zoning maps ....................................................... 26 4.3. Landslide zoning levels ....................................................................... 27 4.4. Landslide zoning map scales ............................................................... 28 4.5. Landslide zoning descriptors ............................................................... 31 4.1 Reliability of landslide zoning ............................................................ 33 References..................................................................................................... 34 5 Input data for landslide risk assessment ..................................... 38 5.1 Landslide inventory mapping .............................................................. 40 5.2 Environmental factors ......................................................................... 44 5.3 Triggering factors ................................................................................ 48 5.4 Elements at risk data ........................................................................... 49 5.5 Quality of the input data ...................................................................... 49 References..................................................................................................... 52 6 Suggested methods for landslide susceptibility assessment ...... 56 6.1 Landslide initiation susceptibility ....................................................... 56 6.1.1 Introduction ................................................................................ 56 6.1.2 Methods for susceptibility assessment related to landslide initiation ..................................................................................... 58 6.1.3 Landslide inventory analysis ..................................................... 59 6.1.4 Knowledge driven methods ....................................................... 60 6.1.5 Data-driven landslide susceptibility assessment methods ......... 61 6.1.6 Physically-based landslide susceptibility assessment methods . 63 6.1.7 Selecting the best method of analysis ........................................ 65 6.1.8 From susceptibility to hazard ..................................................... 67 References ........................................................................................... 69 6.2 Landslide runout .................................................................................. 74 6.2.1 Empirical .................................................................................... 74 6.2.1.1 Geologic evidences ....................................................... 74 6.2.1.2 Geometrical approaches ............................................... 75 6.2.1.3 Volume-change methods .............................................. 76 6.2.2 Rational methods ....................................................................... 77 6.2.2.1 Discrete models ............................................................ 77 6.2.2.2 Continuum based models ............................................. 77 References ........................................................................................... 80 4 Guidelines for landslide susceptibility, hazard and risk zoning 7 Suggested methods for landslide hazard assessment ................. 82 7.1 Landslide frequency assessment ......................................................... 82 7.1.1 Evaluation of the potential for the future slope failures ............ 84 7.1.1.1 Geomechanical approach .............................................. 84 7.1.1.2 Formal probability and reliability analyses .................. 84 7.1.1.3 Event tree methods (logic trees) ................................... 85 7.1.2 Frequency analysis of past landslide events .............................. 85 7.1.2.1 Probability analysis based on series of landslide events 85 7.1.2.2 Correlation with triggers ............................................... 86 7.1.3 Data treatment for frequency analysis ....................................... 87 References ........................................................................................... 88 7.2 Preparing Magnitude-Frequency relations .......................................... 90 7.2.1 Magnitude-Frequency (M-F) curves .......................................... 90 7.2.2 Preparation of M-F relations ...................................................... 92 7.2.2.1 Regionally derived M-F relations ................................. 92 7.2.2.2 Spatial dependence of the M-F relations ...................... 92 7.2.3 Restrictions of M-F relations ..................................................... 92 References ........................................................................................... 94 7.3 Landslide hazard assessment ............................................................... 97 7.3.1 Objectives of the landslide hazard assessment and zoning. Where is hazard determined? ..................................................... 98 7.3.2 Consideration of landslide runout .............................................. 99 7.3.3 Restrictions associated to the scale of analysis ........................ 100 7.3.4 Regional scale hazard analyses ................................................ 101 7.3.5 Local scale hazard assessment ................................................. 104 7.3.5.1 Areal analysis ............................................................. 104 7.3.5.2 Linear analysis ............................................................ 108 7.3.6 Site specific hazard assessment ............................................... 108 7.3.6.1 First-time slope failures .............................................. 108 7.3.6.2 Active Landslides ....................................................... 109 7.3.6.3 Rockfalls ....................................................................