Geological Hazards and Associated Risks
Erosion Risks and Impacts
Drivers of Erosion Risk Factors
- Slopes
- Unconsolidated geological materials
- Climate, aridity, sporadic and torrential rainfall
Erosion Loss and Desertification
- Loss of soil biological-geological system
- Plant and animal life
- Arable land (agricultural resources)
- Desertification
- Silting of reservoirs (Loss of reservoir capacity, hydro damage)
- Sedimentation in river channels (Floods)
Risks from Eroded Material Storage
- The possibility of impact from moving materials, razing or burying people, buildings, crops, etc.
- The fact that the very land on which these people, infrastructure, etc., are settled is moving down the slope.
Factors Increasing Erosion Risk
- Slopes
- Lack of vegetation
- Soil material cohesion
- Arid climate
- Human interventions
- Inappropriate land use
Erosion Prevention Measures
Determine the most appropriate use of land according to its sensitivity to erosion (e.g., prevent logging or cultivation on steep slopes) and protect and maintain the green cover on the slopes.
Desertification in Spain
Significant landslides occur in Spain due to terrain and climatic conditions. Landslides can cause fatalities.
Types of Gravitational Phenomena
Differing Types of Gravitational Phenomena
- Rockfalls: Falling stones, block topples, rock avalanches
- Landslides: Rotational slumps, translational landslides
- Solifluction: Clay-water flows, ice solifluction
- Downhill creep or soil creep
Triggers of Gravitational Phenomena
Movements can be due to natural causes or human activity on the ground.
Gravitational Hazard Characteristics & Damage
- The possibility of impact from moving materials, razing or burying people, buildings, crops, etc.
- The fact that the very land on which these people, infrastructure, etc., are settled is moving down the slope.
Preventing Gravitational Process Risks
- Reducing the inclination of the slope
- Elimination of weight at the head and addition at the foot
- Strengthening and adding weight at the foot of the slope
- Drainage
- Reinforcement with anchors
Subsidence Phenomena and Causes
Subsidence Phenomena and Causes
Subsidence (slow, sustained decreases in soil) is a process that usually causes no casualties but results in large economic losses.
Causes: Tectonic processes, seismic shaking, mining areas, removal of underground fluids, etc.
Damage Caused by Subsidence
Can damage buildings and roads, cause flooding in downstream areas, changes in land slopes, and groundwater contamination.
Expansive Soil Risks and Damage
Soils that significantly change volume by absorbing water.
Damage: Swelling can unsettle building foundations.
Karstic Phenomena Risks, Causes, and Materials
- Sudden collapse of portions of the land and small earthquakes.
- Cause: Karstic processes evolve more rapidly due to the solubility of materials.
- Materials: Gypsum or salt.
Freeze-Thaw Processes and Effects
Freeze-Thaw Causes and Material Effects
Phase changes determine changes in the volume of water in soil and rocks, which causes swelling, rupture, landslides, and disaggregation of blocks or grains.
Frost and Snow Risk Phenomena
As a result of frost and snow, risk constituents include snow avalanches, soil or rock slides, falling materials, and changes in the volume, porosity, or density of the material.
Glacier Origin Risk Events
Avalanches of ice blocks, slab avalanches, floods from rapid melting, breakup of natural dams, etc.
Snow and Ice Risks in Spain
Risks associated with frost and their impact on agriculture and public works.