1 Geohazards: assessment and planning 1 Introduction 1 Risk assessment 5 Remote sensing, aerial photographs and hazards 7 Hazard maps 9 Land-use planning and hazards 12 2 Volcanic activity 16 Introduction 16 Volcanic form and structure 18 Types of central eruption 25 Volcanic products: volatiles 28 Volcanic products: pyroclasts 29 Volcanic products: lava flows 32 Mudflows or lahars 3 7 Volcanic hazard and prediction 38 3 Earthquake activity 59 Introduction 59 Intensity and magnitude of earthquakes 62 Effects of earthquakes 70 Ground conditions and seismicity 72 Methods of seismic investigation 76 Seismic hazard and risk 85 Seismic zoning 87 Earthquake analysis and design 94 Structural damage and its prevention 97 Earthquakes and dams 103 Induced seismicity 105 vi Contents Contentsvii 4 Mass movements 114 Soil creep and valley bulging114 Causes of landslides116 Classification of landslides122 Landslides in soils132 Landslides in rock masses135 A brief note on slope stability analysis139 Monitoring slopes144 Landslide hazard, investigation and mapping150 Methods of slope control and stabilization163 5 Problem soils181 Quicksands 181 Expansive clays 185 Dispersive soils195 Collapsible soils202 Quick clays207 Soils of arid regions 213 Tropical soils218 Peat 226 Frozen soils230 6 River action and control 245 Fluvial processes245 Floods261 Factors affecting run-off264 Assessment of run-off271 Hazard zoning, warning systems and adjustments277 River control and flood regulation281 7 Marine action and control292 Waves293 Tides299 Beach zones300 Coastal erosion304 Beaches and longshore drift306 Storm surges and marine inundation309 Shoreline investigation314 Protective barriers319 Stabilization of longshore drift 325 Tsunamis329 8 Wind action and arid regions 337 Introduction337 Wind action339 Desert dunes345 Stream action in arid and semi-arid regions349 Flooding and sediment problems355 Movement of dust and sand357 Sabkba soil conditions370 Salt weathering374 9 Soil erosion and desertification390 Introduction390 Estimation of soil loss397 Sediment yield400 The Universal Soil Loss Equation404 Soil erosion by wind413 Erosion control and conservation practices419 Assessment of soil erosion426 Desertification436 Irrigation439 10 Waste and its disposal452 Introduction452 Domestic refuse and sanitary landfills454 Hazardous wastes479 Radioactive waste483 Waste materials from mining490 Contaminated land502 Remediation of contaminated land512 11 Groundwater pollution522 Introduction522 A note on groundwater quality523 Rock type, pollution potential and attenuation of a pollutant526 Faulty well design and construction529 Induced infiltration530 Leachate from landfill sites 533 Saline intrusion 538 Nitrate pollution 542 The problem of acid mine drainage 543 Waste waters and effluents from mines 550 Other causes of pollution 554 Groundwater monitoring and artificial recharge 556 12 Ground subsidence 566 Introduction 566 Pillar-and-stall workings and their potential failure 566 Investigations in areas of abandoned mine workings 575 Old mine workings and hazard zoning 580 Measures to reduce or avoid subsidence effects due to old mine workings 584 Old mine shafts 586 Longwall mining and subsidence 5 90 Damage associated with ground movements 5 98 Measures to mitigate the effects of subsidence due to longwall mining 603 Metalliferous mining 605 Subsidence associated with fluid abstraction 607 Index 626