Landslides represent one of the most destructive natural catastrophes. They can reach extremely long distances and velocities, and are capable of wiping out human communities and settlements. Yet landslides have a creative facet as they contribute to the modification of the landscape. They are the consequence of the gravity pull jointly with the tectonic disturbance of our living planet.Landslides are most often studied within a geotechnical and geomorphological perspective. Engineering calculations are traditionally applied to the stability of terrains. In this book, landslides are viewed as a physical phenomenon. A physical understanding of landslides is a basis for modeling and mitigation and for understanding their flow behavior and dynamics. We still know relatively little about many aspects of landslide physics. It is only recently that the field of landslide dynamics is approaching a more mature stage. This is testified by the release of modelling tools for the simulation of landslides and debris flows. In this book the emphasis is placed on the problems at the frontier of landslide research. Each chapter is self-consistent, with questions and arguments introduced from the beginning.

Preface.- 1. Introduction and problems.- 1.1 Landslides: an overview.- 1.1.1. What is a landslide?.- 1.1.2. Landslides as a geological hazard.- 1.1.3. Landslides as a geomorphic driving force.- 1.1.4. Physical aspects of landslides.- 1.2. Types of landslides.- 1.2.1. Geometrical characteristics of a landslide.- 1.2.2. Description of the seven types of movements.- 1.3. A physical classification of Gravity Mass Flows.- 2. Friction, cohesion, and slope stability.- 2.1. Friction and Cohesion.- 2.1.1. Normal and shear stresses.- 2.1.2. Friction.- 2.1.3. Cohesion.- 2.2. Slope Stability 2.2.1. A few words on slope stability.- 2.2.2. An example: layered slope. 2.2.3. A few basics concepts of soil mechanics and an application to slumps.- 2.2.4. Other factors contributing to instability.- 3. Introduction to fluid mechanics.- 3.1. Introduction.- 3.1.1. What is a fluid?.- 3.2.Fluid static.- 3.3. Simple treatment of some topics in fluid dynamics.- 3.3.1. Fluid flow (key concept: velocity field, streamlines, streamtubes).- 3.3.2. Fluid flow in a pipe with a constriction (key concepts: continuity, incompressibility).- 3.3.3. Lift force on a half-cylinder (key concept: energy conservation and the Bernoulli equation).- 3.3.4. Flow of a plate on a viscous fluid (key concepts: no-slip condition, viscosity, Newtonian fluids).- 3.3.5. Fluid pattern around a cylinder (key concepts: Reynolds number, turbulence).- 3.4. Microscopic model of a fluid and mass conservation.- 3.4.1. The pressure in a gas is due to the impact of molecules.- 3.4.2. Viscosity.- 3.5. Conservation of mass: the continuity equation.- 3.5.1. Flux.- 3.5.2. Continuity equation in Cartesian coordinates.- 3.6. A more rigorous approach to Fluid Mechanics: momentum and Navier-Stokes equation.- 3.6.1. Lagrangian and Eulerian viewpoints.- 3.6.2. Momentum equation.- 3.6.3. Analysis of the forces.- 3.6.4. Adding up the rheological properties: the Navier-Stokes equation.- 3.7. Some applications.- 3.7.1. Dimensionless numbers in fluid dynamics.- 3.7.2. Application to open flow of infinite width channel.- 4. Non-Newtonian fluids, mudflows, and debris flows: a rheological approach.- 4.1. Momentum equations, rheology, and fluid flow.- 4.2. Dirty water: the rheology of dilute suspensions.- 4.3. Very dirty water: rheology of clay slurries and muds.- 4.3.1. Clay mixtures.- 4.3.2. Interaction between clay particles.- 4.3.2. Rheology of clay mixtures and other fluids.- 4.3.4. Bingham and Herschel Bulkley.- 4.3.5. Shear strength as a function of the solid concentration.- 4.3.6. Relationship between soil properties and fluid dynamics properties.- 4.4. Behavior of a mudflow described by Bingham rheology: one-dimensional system.- 4.5. Flow of a Bingham fluid in a channel.- 4.6. Rheological flows: general properties.- 4.6.1. Introduction.- 4.6.2. Geological Materials of rheological flows.- 4.6.3. Structure of a debris flow chute and deposit.- 4.6.4. Examples of rheological flows.- 4.7. Debris flows: dynamics.- 4.7.1. Velocity.- 4.7.2. Dynamical description of a debris flow.- 4.7.3. Impact force of a debris flow against a barrier.- 4.7.4. Quasi-periodicity.- 4.7.5. Theoretical and semiempirical formulas to predict the velocity.- 5. A short introduction to the physics of granular media.- 5.1 Introduction to granular materials.- 5.1.1. Solid mechanics: Hooke¿s law, Poisson coefficients, elasticity.- 5.1.2. Granular media in the Earth Sciences. Angle of repose.- 5.1.3. Force between grains.- 5.2. Static of granular materials.- 5.2.1. Pressures inside a container filled with granular material.- 5.2.2. Force chains.- 5.3. Grain Collisions.- 5.3.1. Grain-wall collisions.- 5.3.2. Grain-grain collisions.- 5.4. Dynamics of granular materials; avalanching.- 5.4.1. ...