Geol Exam 3 Mega Reviewer PDF

Geol Exam 3 Mega Reviewer I. Definition of Geohazards A. Definition: potentially destructive process that could harm man and his resources c) Liquefaction (turning solid into liquid) 1. Disaster:F(Hazard, People & Resources at risk)...

Geol Exam 3 Mega Reviewer I. Definition of Geohazards A. Definition: potentially destructive process that could harm man and his resources c) Liquefaction (turning solid into liquid) 1. Disaster:F(Hazard, People & Resources at risk) a) No people and resources ⇒ no disaster b) No hazard ⇒ no disaster B. Geology and Society: Challenges - Dwindling non-renewable resources, environmental degradation against human survival and d) Fire (indirect) geohazards II. Types of Geohazards A. Earthquake: the vibration of the earth, caused by the rupture and sudden movement of rocks that have been strained beyond their elastic limits. 1. Elastic Rebound Theory: Elastic strain is recoverable portion e) Landslides a) Stress ⇒ rupture or slip and elastic rebound b) Old fault = Friction, New fault = Strength c) Slip Rate and Occurence grounded on rate of motion or friction/strength 2. Earthquake Generators: (For Tectonic Earthquakes) Plate boundaries (subduction zones, mid-oceanic ridges, f) Subsidence (land sinking) transform faults) and Active Faults 3. Earthquake Hazards: a) Ground Rupture g) Flooding (dam failure) b) Ground Shaking  4. Engineering Solutions: Shear wall and use 6. Volcanic Hazards of reinforced concrete & steel, Shock a) Lava Flow: Burial absorbers between. Etc 5. Earthquake Prediction: a) Preparedness: Seismic risk map, Strict building code, Zoning and land use b) Unusual Animal Behavior c) use of SAR interferometry and GPS d) use of seismic gaps b) Pyroclastic Flow & Pyroclastic Surge 6. Issues and Problems: (Death by Asphyxia) a) How to evacuate megacities? (Mass transport, unknown destination, various evacuation routes, Traffic jam management, Food and drink for millions) b) Who will be left behind? (security of properties) B. Volcanoes: an opening in the Earth's crust that allows lava, ash, and gases to escape, and the resulting cone-shaped mountain or hill c) Tephra Fall / Ash Fall (hazard to aviation) that forms around the vent 1. Plate Tectonics and Volcanism: Hot Spots that are either oceanic or continental a) Plates move as hot spots remain stationary. 2. Causes: Internal and External factors a) Internal: vesiculation or degassing of d) Global Cooling magma and magma influx b) External: load pressing, tectonic pressure, tides 3. Emissions: Lava (Lava Flow), volcanic gases, Pyroclasts - Tephra (Rock Fragments - Pumice, Ash) 4. Types of Eruption: Explosive and Effusive e) Noxious gas – CO2 a) Explosive: cooler, more viscous magma reaches the surface - more gas content, meaning more fragments b) Effusive: hot, runny basalt magma reaches the surface. The magma has low viscosity and low gas content. Flows 5. Caldera: Volcano with a crater greater than 2 km in diameter  f) Lahar: Burial and Erosion 3. Materials Involved a) Rock: a hard or firm mass that was intact and in its natural place before the initiation of movement b) Soil: an aggregate of minerals and rocks that either was transported or was formed by the weathering of rock in g) Debris Avalanche place 4. Speed of a Landslide: a) Very Slow: Creep b) Moderate: Slumps and Earthflows c) Rapid to Very Rapid: Rockfalls and Avalanches 5. Water on Slope Stability: - a small 7. Volcanic Benefits amount of water in pore space that is a) Fertile Soil mostly occupied by air produces a b) Valuable Minerals capillary force which holds particles c) Water Reservoir together, resulting in more cohesion d) Geothermal Energy a) a large amount of water occupying all e) Scenic Beauty the pore space exerts pressure on the particles, reducing cohesion C. Landslides: general term for rapid downslope movements/failure 6. Human Activity on Landslide Frequency: 1. Mass Wasting: even more general and Logging operations , Construction leads to includes slow movements (creep, slow oversteepening of slopes, Buildings and flows) structures on a naturally unstable slope, a) Mass wasting / slope failure / landslides Irrigation, watering the lawn – all downslope movement of rock and sediment that occurs at the surface of 7. Recognizing Past Landslide Activity: the earth (also underwater) in response Scars, Disrupted Topography, Records, to gravity. Titled Vegetation, Cracks in buildings 2. Landslide Classification: Based on the 8. Mitigation Measures: type of MATERIALS involved, the SPEED a) Identify potential hazard (velocity) of movement, and the TYPE or mechanism of downslope movement b) Slope reduction and revegetation  c) Use of retention structures d) Removing Fluid D. Rivers and Flooding: 1. Causes: Excessive rainfall, Limited river channel capacity (based on width, depth and gradient) and Dam failure 2. Run off: water from rainfall that remains on the surface of the Earth before going into streams 3. Natural Levees: build-up along the river bank due to deposition of suspended sediment during floods 4. Floodplains: surface adjacent to a channel that is frequently flooded 5.