EOS 170 Prep PDF

MODULE - A - EARTH'S STRUCTURE + TECTONICS 1.​ How is it that the compositions of certain meteorites represent the bulk composition of the planet Earth? Approximately what age are these meteorites? -​ Certain meteorites, like chondrites, are thought to have a composition similar to...

MODULE - A - EARTH'S STRUCTURE + TECTONICS 1.​ How is it that the compositions of certain meteorites represent the bulk composition of the planet Earth? Approximately what age are these meteorites? -​ Certain meteorites, like chondrites, are thought to have a composition similar to the bulk of the Earth because they represent primitive solar system material that hasn’t undergone differentiation. These meteorites are approximately 4.5 billion years old, dating back to the formation of the solar system. 2.​ Rheological layers and compositional layers. -​ Lithosphere (rigid), asthenosphere (plastic), mesosphere (solid by plastic under pressure), outer core (liquid), and inner core (solid) -​ Crust (silicates), mantle (silicate minerals rich in Mg and Fe), and core (iron-nickel alloy). 3.​ Oceanic Vs continental crust, composition, physical properties and deformation. -​ Oceanic crust: basaltic rich in iron and magnesium, denser and thinner, oceanic crust sinks, forming trenches and volcanic arcs. -​ Continental crust: Granitic rich in silica and aluminum, less dense and thicker, crustal thickening and mountain building. 4.​ Coronal Mass Ejections (CMEs) and Geomagnetic Storms. -​ Coronal mass ejections are large ejections of plasma and magnetic fields from the sun’s corona. Geomagnetic storms occur when CME-induced solar winds interact with Earth’s magnetosphere. Impacts humans through satellite damage, gps and communication disruptions and even power grid failures. 5.​ Evidence Supporting Continental Drift and Plate tectonics -​ Geological evidence for continental drift includes fossil distribution matching across continents. -​ Geophysical evidence for plate tectonics including magnetic striping on the seafloor shows symmetrical patterns of magnetic reversal on either side of mid-ocean ridges. 6.​ Bathymetric features and plate tectonics -​ Features discovered by Sonar include mid-ocean ridges, deep ocean trenches and fracture zones. MODULE - B - EARTHQUAKES 1.​ Fault types -​ There are three fault types, normal faults occur with extension, hanging wall moves down relative to the footwall. Reverse or thrust faults occur with compression, hanging wall moves up relative to the footwall. Strike-slip faults occur with lateral motion, blocks slide past each other horizontally. -​ The largest earthquakes occur at reverse faults. Subduction zones because they generate immense stress accumulation and release. 2.​ Seismic waves -​ P-waves are the fastest, compressional, travel through solids and liquids, least damaging. -​ S-waves are slower, shear, travel through solids only, cause moderate damage. -​ Surface waves travel along the surface love and rayleigh slowest but most destructive due to high amplitude. -​ Can detect earthquake location, measure time difference between p and s waves at multiple seismic stations to triangulate the epicenter. -​ Detect p waves to provide seconds to minutes of warning before destructive later waves. 3.​ Magnitude VS intensity -​ Magnitude measures energy released at the source -​ Intensity describes shaking effects on people and structures -​ 2010 Haiti earthquake high intensity due to shallow focus and poor building standards. 4.​ Factors controlling peak intensity -​ Proximity to epicenter -​ Depth of focus (shallow earthquakes are more intense) -​ Local geology ( soft soils amplify shaking) -​ Building quality 5.​ Increasing Seismic Risk -​ Urbanization and population growth in seismic zones -​ Poor enforcement of building codes 6.​ Building heights and earthquake damage -​ Resonance occurs when the building's natural frequency matches seismic wave frequency. Case study 1985 mexico city earthquake mid rise buildings resonated with long period surface waves, collapsing while taller or shorter buildings survived. 7.​ Interplate Earthquakes -​ Found on reactive ancient faults or rift zones within plates. Their driving force is mantle convection, lithospheric stress or distance plate boundary interactions. 8.​ Seismic risk in Victoria, BC -​ Population growth: increased exposure due to urbanization -​ Mitigation: improved building codes and early warning systems can reduce risk. -​ Hazards: Nearby subduction zone (Cascadia) capable of generating megathrust earthquakes. MODULE - C - VOLCANOES 1.​ Magma Viscosity and Explosiveness -​ Importance of viscosity: higher viscosity magma traps gas more effectively, leading to pressure buildup and explosive eruptions. Lower viscosity magma allows gas to escape easily, resulting in effusive eruptions. -​ Magma compositions: From lowest to highest viscosity: Basaltic, Andesitic, Rhyolitic 2.​ Pyroclastic Flows -​ A pyroclastic flow is a fast-moving current of hot gas, ash, and volcanic material. -​ Formation: Collapse of an eruption column, explosive dome collapse, direct lateral blasts. -​ An example is Mount pelee 1902, killing about 30 thousand people due to pyroclastic flows caused by dome collapse. 3.​ Mount St Helens 1980 -​ Northword focus: the north face of the volcano collapsed in a massive landslide, releasing pressure and directing the lateral blast. -​ Predictive measurements: increased seismic activity, ground deformation, gas emissions indicating rising magma. 4.​ Eyjafjallajokull 2010 -​ Has unusual features such as: mixed eruption cycle with explosive phases due to interaction between magma and glacial ice. -​ Unlike typical effusive eruptions in Iceland, which are associated with basaltic magma at rift zones. -​ Human impacts include: air travel disrupted across Europe due to volcanic ash clouds. Economic losses in the aviation and tourism industries. 5.​ Tectonic settings -​ A: Ocean hot spot - B: mid ocean ridge - C: Volcanic arc -​ Least explosive: mid ocean ridge ( basaltic, low viscosity) -​ Most explosive: volcanic arc (andesitic/rhyolitic, high viscosity) -​ Majority of volcanism occurs at mid ocean ridges responsible for about 80% -​ Shield volcanoes occur at oceanic hotspots, stratovolcanoes occur at volcanic arcs. -​ Melting at D occurs by decompression melting due to upwelling mantle materials as plates diverge. MODULE - D - LANDSLIDES 1.​ How water increases the likelihood of landslides -​ Adds weight: water increases the mass of soil and rock, making the slope more prone to failure due to the added gravitational pull. - Washington -​ Reduces friction: water infiltrates the ground, increasing pore water pressure and reducing the friction that normally holds soil and rock in place - Nepal -​ Erodes the slopes base: streams or waves can undercut the base of a slope, removing support and making it more likely to collapse. - California 2.​ Key features of a landslide -​ Head scarp: the steep, exposed surface at the top of the landslide, marks where the material detached from the sable ground. -​ Transverse Cracks: cracks that develop perpendicular to the slopes movement, indicate tension within the sliding mass. -​ Toe: the accumulation of displaced material at the base of the landslide, can block rivers or roads, creating secondary hazards like flooding. -​ Basal failure surface: the curved plane along which the slide occurs, often found at the boundary between those surface material and more stable underlying layers. 3.​ Montecito Mudflows 2018 -​ Impact of debris flow. -​ Preconditions: severe wildfires burned vegetation, reducing the soils stability and ability to absorb water. Heavy rainfall occurred shortly after the fires causing water to flow rapidly downhill picking up ash debris and soil. -​ Trigger: intense, short duration rainfall over burnt slopes led to the sudden formation of mudflows -​ People did not evacuate because they had already been evacuated for the wildfire and were hesitant to leave again, it gave them a false sense of security. MODULE - D - LANDSLIDES 1.​ Mass movements -​ large volumes of material move downslope under gravity. Landslides (rock, soil, debris, or mud), snow avalanches, lava flows, pyroclastic flows, lahars. 2.​ Forces influencing Landslides: -​ Gravitational forces act in two components: -​ Parallel to slope: pulls material downslope -​ Perpendicular to slope: holds material in place -​ Failure occurs when the downslope force exceed frictional resistance 3.​ Key factors promoting Landslides -​ Slope angle: steeper slopes are more unstable -​ Added mass: saturation with water increases weight -​ Shaking: nearby earthquakes can trigger movement -​ Friction reduction: decreased cohesion of slope material 4.​ Role of water -​ Increased weight: replaces air in pore spaces, increases density  -​ Pore pressure: water is incompressible, reducing internal material strength. -​ Freeze-thaw weathering: water expands when freezing, widening cracks and disintegrating rock. -​ Groundwater: weakens rock by dissolving cement minerals or eroding materials. 5.​ Geological influences -​ Rock dissolution, clays expand when wet reducing rock strength, bedding planes: sliding occurs preferentially along weak sedimentary rock layers, tectonics. 6.​ Preconditions and Triggers -​ Preconditions: factors that bring slopes to the brink of failure, like tectonic steeping or weakened rock. -​ Triggers: events that push slopes over the edge, like earthquakes or rainfall. 7.​ Landslide Classification -​ Falls: downward free fall of material, rock fall from cliff fractures -​ Slides: movement along a failure plane, rotational slides (material rotates around a curved surface for a short distance). Transitional slides (moves along plane surfaces longer and faster with head scraps, transverse cracks, toe scarps, -​ Flows: material fluidized during movements -​ Earth flows: slow moving soil -​ Debris flows: rock, soil, vegetation -​ Mud flows: wet mud -​ Lahars: wet volcanic ash -​ Creep: slowest form of failure, caused by freeze thaw cycles, wetting/drying of clays, soil heating/cooling -​ Avalanches: fast moving disintegration of rock -​ Rock avalanches: start as rick falls, evolve into debris slides -​ Sturzstroms: long distance avalanches with vertical drop 8.​ 2014 Oso Washington Landslide -​ Initially a highly mobile debris slide, followed 2 minutes later by a rotational rock slide. Causes: intense rainfall, river incision, clay rich glacial till weakened the slope, past instability -​ The landslide crossed the river and engulfed Steelhead, killing 43 people and destroying 35 homes. 9.​ 2018 Montecito Mud Flow -​ Mud and debris flow caused by burned vegetation which destabilized soil, created ash layers with low permeability, and intense rainfall triggered the flows. Destroyed 100+ homes and killed 21 people, evacuation fatigue. 10.​2010 Mt Meager BC composite landslide. -​ Massive composite landslide at volcanic peak, initially rock fall dropped, triggered rock avalanche into the river, causing the weakening of volcanic rocks through hydrothermal activity, no fatalities due to remote location 11.​Landslide risk management -​ Hazard reduction by scaling, benching, mechanical support, drainage modification.  -​ Monitoring and early warning through satellite radar, gps, rain gauges, acoustic flow monitors, laser ranging instruments. MODULE - E - TSUNAMIS 1.​ Why is a 5 m-high tsunami wave more devastating than a 5 m-high wind wave? -​ Tsunami wave: long wave up to 100s km and high energy throughout its depths, causes extreme flooding as it travels far inland with massive volume and momentum. -​ Wind wave: short wavelengths tens of meters and energy limited to surface water, breaks and dissipates energy quickly near the shore. 2.​ Why do megathrust earthquakes produce ocean-wide tsunamis, white landslides tsunamis are local? -​ Megathrust earthquakes displace large sections of the sea floor transferring vase energy to the water column over a wide area - indian ocean -​ Landslide tsunamis result from displaced water due to falling debris; energy is localized near the event - lituya bay 3.​ What was unusual about the 2018 Palu Tsunami? -​ The tsunami was caused by a strike slip fault which rarely generates significant vertical seafloor displacement. -​ Possible mechanisms of this: submarine landslides triggered by seismic shaking, direct fault displacement of the seafloor, resonance or amplification of waves in play bays narrow inlet 4.​ Comparison of the Grand Banks and Lituya Bay Tsunamis -​ Gran banks was triggered by a submarine earthquake that caused an undersea landslide, discovered via unusual telegraph cable breaks and water level changes. Was triggered by a submarine landslide from a deep sea earthquake, affecting coastal villages with moderate fatalities. -​ The Lituya Bay Tsunami was triggered by a landslide from a mountainside into the bay after an earthquake, created the tallest recorded wave at 524 m, was triggered by a terrestrial landslide into a confined bay, is highly localized, few casualties but catastrophic locally for vergestation and infrastructure. MODULE - E - TSUNAMIS 1.​ Tsunami means harbour wave in japanese. -​ Caused by geological events that displace large water volumes: earthquakes, volcanic eruptions, landslides, meteorite impacts. -​ Tidal waves are not caused by tides. 2.​ Water displacement and reach -​ Larger displaced water volumes lead to ocean wide tsunamis. 3.​ Wave propagation  -​ Normal waves: wind driven with wavelengths of 100s of meters, shoaling in shallow waters reduces wavelengths to 10s of meters and increases height up to 15 meters. -​ Tsunami waves: wavelengths of 100s of kilometers in open oceans, move at high speeds, carrying massive momentum, danger lies in run up and the mass of water. 4.​ Wave behavior -​ Refraction: long wavelengths allow waves to refract around islands, affecting all shorelines. Uneven bathymetry causes focusing or defocusing the bend of waves inward or outward. South American tsunamis focus towards Japan away from australia. 5.​ Wave sequence -​ Up to 10 wave peaks separated by 10 - 60 minutes, the largest wave may not be the first, ocean drawback occurs only when the first wave is a trough. 6.​ Run up and devastation -​ Run up heights depend on bathymetry and coastline shape -​ Locations like hawaii and port Alberni are prone to devastation. 7.​ Seiches -​ Standing waves in enclosed or partially enclosed water bodies like lakes. -​ Caused by strong persistant winds, tectonic tilting from nearby earthquakes, rarely distant earthquake surface waves. -​ Comparison to tsunamis: landslides more commonly trigger tsunamis due to smaller wavelengths relative to water body dimensions. 8.​ Preparation and mitigation -​ Early warning systems -​ Pacific tsunami warning center: based on rapid earthquake data but prone to false alarms. -​ DART system: ocean bottom pressure sensors detect deep water waves -​ Local warning systems: coastal radar detects wave anomalies 80 km offshore. -​ Mitigation strategies -​ Hazard maps, raised earth parks, structural measures like sea walls. 9.​ 2004 Indian Ocean Tsunami -​ Caused by the third largest recorded earthquake, no warning system in place, huge run ups with 160 thousand deaths and then another 60 k deaths in another 13 countries 10.​2011 Tohoku Tsunami -​ Megathrust earthquake along the japan trench. Wave warning was issued, waves overtopped the world's tallest tsunami walls and flooded assumed safe areas. Max run up heights 40m and about 18.5 k deaths by drowning, 3.6 billion in economic losses. 11.​1958 Lituya Bay Tsunami -​ Caused by a 7.8 earthquake on the fairweather strike slip fault triggered by a massive rockfall. The massive rockfall created a giant local wave with a  maximum run up height of 500 m. limited to the narrow inlet, two fishing boats sunk, one survived unscathed. 12.​2017 Nuugaatsiaq tsunami -​ Caused by a rock avalanche into karat fjord greenland, likely caused by permafrost melting and glacier retreat from global warming. Swept 11 houses into the sea and killed 4 people. 13.​1929 Grand Banks Tsunami -​ Caused by a 7.2 strike slip earthquake triggered a 200km submarine landslide in the grand banks off newfoundland. The landslide caused a turbidity current that broke telegraph cables, tsunami waves warped the sea surface and propagated. 28th deaths - deadliest tsunami in canadian history 14.​1959 Hebgen Lake Seiche -​ Caused by a 7.2 earthquake along the Hebgen normal fault in montana. Earthquake caused shoreline to drop, creating a 7 m seiche wave in the lake, triggered a massive landslide, blocking the madison river and forming quake lake, it flooded maddison valley, the combined landslide and seiche killed 28. MODULE - F - WEATHER AND CLIMATE HAZARDS 1.​ Deadliest weather events in Bangladesh -​ Cyclones (tropical storms) devastating due to low lying geography makes the region prone to storm surges and flooding, high population density along coastal areas, limited infrastructure and emergency preparedness -​ Future risks: likely to increase due to climate change causing rising sea level, increased cyclone intensity, continued population growth in vulnerable regions. 2.​ Five Mechanisms by which Hurricanes Kill and destroy. -​ Storm Surge: Flooding from seawater pushed ashore by winds -​ High winds: structural damage, flying debris -​ Heavy Rainfall: inland flooring from prolonged rains -​ Tornadoes: Hurricanes can spawn tornadoes, adding to destruction -​ Infrastructure collapse: damage to power, communication and transportation systems. 3.​ Most common types of flooding in Canada -​ River flooding: developed by snowmelt, heavy rain or ice jams cause rivers to overflow their banks. -​ Seasonal (spring & fall), slow onset by widespread impacts -​ Examples: red river floods in Manitoba. 4.​ Hurricane Katrina: Most devastating Aspects -​ Storm surge overwhelmed levees, causing catastrophic flooding, slow emergency response and evacuation failures -​ Over 1800 deaths and displacement of thousands, infrastructure destruction and long term economic impacts. -​ Prevention by better levee design and maintenance, improved emergency preparedness and evacuation plans.  5.​ Tornado Formation in North America -​ Tornado alley ( Oklahoma, Kansas, Manitodba) -​ Warm moist air from the Gulf of Mexico collides with cold dry air from Canada. -​ Jet steam adds wind shear, creating rotating updrafts from tornadoes. 6.​ Forest Wildfire Suppression Techniques -​ Water Bombing: Removes heat (cooling) -​ Firebreaks: removes fuel (cleaning vegetation) -​ Backburning: removes fuel (controlled burning ahead of the fire) -​ Fire Retardants: reduces oxygen supply and slows spread 7.​ Factors in the 2016 Fort McMurray Wildfire -​ Dry conditions: low humidity and lack of precipitation -​ High winds: spread the fire rapidly -​ Hot temperatures: created ideal wildfire conditions -​ Human proximity: the fire spread into populated areas, causing evacuations and damage. MODULE - F - WIND AND CLIMATE HAZARDS Wind Hazards 1.​ Tropical cyclones: storms with sustained winds > 120 km/h -​ Formation requires warm seawater, unstable air for cyclonic rotation and weak vertical wind shear for storm stability. -​ Stages of development: tropical disturbance (low pressure with winds), tropical depression (winds strengthen), tropical storm (winds with cyclonic patterns), tropical cyclone (winds exceed 120; features an eye and eyewall) -​ Dissipation occurs upon landfall or over colder waters. 2.​ Coriolis Effect -​ Governs cyclonic motion and path deflection. -​ Causes: counterclockwise rotation in the northern hemisphere or clockwise rotation in the southern hemisphere. 3.​ Cyclone paths -​ In the north atlantic: begin westward due to trade winds, then curve northward and then eastward under the influence of westerly winds. 4.​ Saffir-Simpson Hurricane Wind Scale: -​ Categories 1-5 based on: -​ Wind speed, pressure in the eye, damage potential 5.​ Storm Surges -​ Causes most fatalities -​ Result from: onshore winds, low atmospheric pressure -​ Impact greatest during high tide, 15-30 km to the right of landfall 6.​ Tornadoes  -​ Winds can reach up to 500km/h, requiring specific atmospheric conditions: interaction of jet stream winds, cool dry air, and warm moist air, sometimes involving a fourth air mass of warm dry air. -​ Develops from super-cell thunderstorms with an anvil shape -​ Classified using the Fujita Scale (F0 - F5) based on: wind speed, path length and width, damage caused. 7.​ Key takeaways -​ Tropical cyclones and tornadoes are driven by specific atmospheric and geographic conditions. -​ Their strength, path and impacts are measured using distinct scales. -​ Understanding wind hazards helps in mitigating damage. Flooding Hazards 1.​ Causes and Impact -​ River flooding: occurs when a river's carrying capacity is exceeded due to excessive precipitation upstream. -​ Forms floodplains over time, which are attractive to human settlement due to: fertile soils, freshwater availability, transportation advantages, flat lands. -​ Impacts: most widespread natural disaster globally, increased by climate change, growing populations in flood prone areas. -​ Dangers include: loss of life, infrastructure damage, water contamination. 2.​ Hydrometeorological floods (caused by weather conditions) -​ Rainfall floods: prolonged heavy rain over large areas -​ Flash floods: torrential rain over small areas in less than 6 hours -​ Snowmelt floods: melting heavy snowpack or rapid thaws -​ Rain on snow floods: heavy rain on snowpack causing runoff and potential building damages or avalanches. -​ Ice jam floods: accumulated ice blocks river flow, occurs during freeze up in winter or break up in spring. 3.​ Outburst floods (caused by natural dam failures) -​ Dams formed by landslides, lava flows, or glaciers. -​ Particularly catastrophic -​ Jokulhlaups: outburst floods from glaciers, often triggered by volcanic eruptions under ice. 4.​ Key takeaways -​ Flooding is a major global hazard, made worse by human settlement patterns and climate change.