Geological Hazards Flashcards
How does convection play a role in both the mantle and the atmosphere?
Heat transfer in a liquid (magma, ocean water, and air).
Can come from the sun and effect the air.
Hot things rise & cold things sink.
Convection of air in the troposphere.
Influences where wet and dry areas are.
How do ocean surface temperatures play a role in weather?
El Nino: Abnormal warming in equatorial waters = wetter than normal conditions across the southern part of North America.
La Nina: Abnormal cooling in equatorial waters = dryer than normal conditions across the southern part of North America.
How does the density of material affect its buoyancy? How does this relate to convection?
Hot things rise; cold things sink.
Starts a cycle that leads to convection.
The thing’s temperature effects its density: more heat = less dense; less heat = more dense.
What happens to the density of water when it freezes?
It decreases because ice has a lower density than water which is why it rises in drinks.
Why are salinity and temperature important with regard to deep-water currents?
Deep ocean currents are driven by density. Salinity effects density. There is a large current that runs around the whole planet. Salt water has a different density than fresh water. If this current is changed, the weather can be changed. Fresh water is colder than salt water.
What is Pangea?
A supercontinent that existed during the late Paleozoic and early Mesozoic eras that includes all of the landmasses.
Why is the discovery of fossil remains of Mesosaurus in both South America and Africa, but nowhere else, important support for continental drift?
The Mesosaurus was a four legged creature who couldn’t swim. If they are found on both continents, it must have walked across which prove that the continents were once stuck together.
Radioactive Decay
The process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles (ionizing radiation).
Mantle Convection
Heat is carried from the interior of the Earth to the surface. Plates are continuously being created and consumed at their opposite plate boundaries. Accretion occurs as mantle is added to the growing edges of a plate, usually associated with seafloor spreading. This hot added material cools down by conduction and convection of heat. At the consumption edges of the plate, the material has thermally contracted to become dense, and it sinks under its own weight in the process of subduction at an ocean trench. It is because the mantle can convect that the tectonic plates are able to move around the Earth’s surface.
Divergent Margins (plate tectonics)
Plates move away from each other
Lava comes up between them
Mostly happens in oceanic plates
Newer rock forms between them
Transform Margins (plate tectonics)
Plates slide next (past) each other
Convergent Margins (plate tectonics)
One plate is being pulled under another plate
One plate has a higher density than the other
The higher density plates go underneath the lesser density plates
Hot-spot volcanism
Hawaii
Hot Spot volcanoes are recognized by an age progression from one end of the chain to the other. An active volcano commonly serves as an “anchor” at one end of the chain.
Atmosphere
Made of gas
Gets thinner
Separated into layers
Atmosphere compostition
Nitrogen
Oxygen
Argon
Carbon dioxide
Atmosphere layers
Defined by thermal characteristics, density, composition, and movement. Exosphere (highest) Thermosphere Mesosphere Stratosphere Troposphere (lowest)
Exosphere (atmosphere layers)
Gas escapes to space
Thermosphere (atmosphere layers)
Very small amounts of gas
Aurora
Mesosphere (atmosphere layers)
Small amounts of gas
Slows meteors down
Stratosphere (atmosphere layers)
Ozone created
NO CONVECTION
Troposphere (atmosphere layers)
All weather happens here
Hydrosphere
Water (oceans, lakes, rivers, groundwater, and ice)
Lithosphere
Earth’s crust
“Great Ocean Conveyor Belt”
Constantly moving system of deep-ocean circulation driven by temperature and salinity.
Cold, salty water is dense and sinks to the bottom of the ocean while warm water is less dense and rises to the surface.
The ocean conveyor gets it “start” in the Norwegian Sea, where warm water from the Gulf Stream heats the atmosphere in the cold northern latitudes. This loss of heat to the atmosphere makes the water cooler and denser, causing it to sink to the bottom of the ocean.
Surface ocean currents
Driven by wind
Northern Hemisphere: clockwise rotation
Southern Hemisphere: counterclockwise rotation
Phases of Matter
Solids: atoms bound in a single crystallized structure, very little movement, + heat –> liquid.
Liquid: moderate speed of atoms, + heat = gas.
Gas: very fast moving atoms, vapor
Takes more energy to go from a solid to a liquid.
Sublimination (phases of matter)
Going directly from a solid to a vapor.
Coriolis Effect
Leads to deflection of moving air masses because the earth is rotating underneath the atmosphere
Northern Hemisphere = moves right
Southern Hemisphere = moves left
Hadley Cell
A pattern of atmospheric circulation in which warm air rises near the equator, cools as it travels poleward at high altitude, sinks as cold air, and warms as it travels equatorward.
How does the volatile content of magma affect the explosiveness of a volcano?
Shaking a soda
How does rock chemistry affect the explosively of a volcano?
The higher the silica content, the more explosive it is.
Mafic rock
Low silica content
Intermediate rock
Moderate silica content
Felsic rock
High silica content
Basalt rock
Low silica content
Mafic rock
Andesite rock
Moderate silica content
Intermediate rock
Dacite rock
Moderate to high silica content
Intermediate rock
Rhyolite
Very high silica content
Felsic rock
How do volcanoes relate to plate tectonics?
Volcanoes form as a result of plate tectonics. When plates are pushing, pulling, and grinding they cause volcanoes. Magma that reaches the surface of the earth produces volcanoes where plates collide or spread apart.They form either at mid-ocean ridges - divergent plate margins, or above subduction zones. A few form within plates as a result of hot-spot activity.
What is Mount Mazama? Why is it important for absolute age dating?
Need igneous rock?
How fast can a pyroclastic density cloud move?
700 km/h (450 mph)
Why does Yellowstone National Park have geysers?
Because there is a volcano underneath. The geyser basin is squeezed between two lava flows.
Phreatomagmatic
Juvenile forming eruptions as a result of interaction between water and magma.
What would happen if a volcano erupted under a glacier?
Eyjafjallajökull
Glacier is melted into a lake by the rising lava. The water quickly cools the lava, resulting in pillow lava shapes. Pillow lava breaks off and rolls down the volcano slopes.
Viscosity
A material’s resistance to flow
Difference between water and honey
Hawaiian & Icelandic (eruptive styles)
Gas poor
Fissures eruptions
Long duration
Strombolian (eruptive styles)
Slightly viscous
Gas poor
Localized on fissures
Near continuous
Vulcanian (eruptive styles)
Moderately viscous
Moderate gas
Isolated
Intermittent activity
Plinian (eruptive styles)
Very destructive Very viscous Very high gas content Isolated Episodic activity Can produce shockwave Opens with a pyroclastic flow
Shield volcano
Effusive eruption
Broad flanks formed by lava flow
Causes of eruption
Magma chamber size
Volatile content
Melting due to temperature, pressure, and water content
Injection of mafic magma into felsic magma
Pyroclastic flow
An incandescent, ground hugging cloud of pumice and dust that flows down the flank of a volcano
Hazards: eruptive column collapse & large scale dome collapse
Lahar
Mudflow involving volcaniclastic material
Controls on Volcanic Styles
Silica content
Volatile content
Major minerals
Different rock types
Effusive eruption vents
Fountains curtain of fire, fissure, lava lakes, splatter cones, hornitio
Fountains (effusive eruption vents)
Eruption focused at a point
What makes a volcano effusive?
Low gas content
Mafic composition
Intermediate rock
Moderate silica content
Felsic rock
High silica content
Basalt rock
Low silica content
Mafic rock
Andesite rock
Moderate silica content
Intermediate rock
Dacite rock
Moderate to high silica content
Intermediate rock
Rhyolite
Very high silica content
Felsic rock
How do volcanoes relate to plate tectonics?
Volcanoes form as a result of plate tectonics. When plates are pushing, pulling, and grinding they cause volcanoes. Magma that reaches the surface of the earth produces volcanoes where plates collide or spread apart.They form either at mid-ocean ridges - divergent plate margins, or above subduction zones. A few form within plates as a result of hot-spot activity.
What is Mount Mazama? Why is it important for absolute age dating?
Need igneous rock?
How fast can a pyroclastic density cloud move?
700 km/h (450 mph)
Why does Yellowstone National Park have geysers?
Because there is a volcano underneath. The geyser basin is squeezed between two lava flows.
Phreatomagmatic
Juvenile forming eruptions as a result of interaction between water and magma.
What would happen if a volcano erupted under a glacier?
Eyjafjallajökull
Glacier is melted into a lake by the rising lava. The water quickly cools the lava, resulting in pillow lava shapes. Pillow lava breaks off and rolls down the volcano slopes.
Viscosity
A material’s resistance to flow
Difference between water and honey
Hawaiian & Icelandic (eruptive styles)
Gas poor
Fissures eruptions
Long duration
Strombolian (eruptive styles)
Slightly viscous
Gas poor
Localized on fissures
Near continuous
Vulcanian (eruptive styles)
Moderately viscous
Moderate gas
Isolated
Intermittent activity
Plinian (eruptive styles)
Very destructive Very viscous Very high gas content Isolated Episodic activity Can produce shockwave Opens with a pyroclastic flow
Shield volcano
Effusive eruption
Broad flanks formed by lava flow
Causes of eruption
Magma chamber size
Volatile content
Melting due to temperature, pressure, and water content
Injection of mafic magma into felsic magma
Pyroclastic flow
An incandescent, ground hugging cloud of pumice and dust that flows down the flank of a volcano
Hazards: eruptive column collapse & large scale dome collapse
Lahar
Mudflow involving volcaniclastic material
Controls on Volcanic Styles
Silica content
Volatile content
Major minerals
Different rock types
Effusive eruption vents
Fountains curtain of fire, fissure, lava lakes, splatter cones, hornitio
Fountains (effusive eruption vents)
Eruption focused at a point
What makes a volcano effusive?
Low gas content
Mafic composition
