Podcast
Questions and Answers
Harry Hess found out that the youngest rocks on the floor of the Atlantic Ocean were in the ______.
Harry Hess found out that the youngest rocks on the floor of the Atlantic Ocean were in the ______.
middle
The lithosphere is broken up into large slabs of rock called ______ plates.
The lithosphere is broken up into large slabs of rock called ______ plates.
tectonic
Hot magma rises because it becomes less dense with ______.
Hot magma rises because it becomes less dense with ______.
heat
At constructive plate margins, hot magma rises and creates an ocean ______.
At constructive plate margins, hot magma rises and creates an ocean ______.
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When a plate subducts at a destructive plate boundary, the dense plate sinking into the mantle causes ______.
When a plate subducts at a destructive plate boundary, the dense plate sinking into the mantle causes ______.
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Sea floor spreading happens when plates ______ apart.
Sea floor spreading happens when plates ______ apart.
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The pressure released when two plates separate forms ______.
The pressure released when two plates separate forms ______.
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Less explosive underwater ______ are formed as magma rises in between the two separating plates.
Less explosive underwater ______ are formed as magma rises in between the two separating plates.
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Acid rain is formed when volcanic gases like sulfur dioxide mix with ______ vapour in the atmosphere.
Acid rain is formed when volcanic gases like sulfur dioxide mix with ______ vapour in the atmosphere.
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Ash fallout consists of material ejected from a volcano during an ______.
Ash fallout consists of material ejected from a volcano during an ______.
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Large tephra tends to fall ______ to the volcano, while microscopic fragments can travel further away.
Large tephra tends to fall ______ to the volcano, while microscopic fragments can travel further away.
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Volcanic gases can create an increased ______ effect, leading to global warming.
Volcanic gases can create an increased ______ effect, leading to global warming.
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Short term responses to volcanic activity include evacuating people and providing emergency ______ supplies.
Short term responses to volcanic activity include evacuating people and providing emergency ______ supplies.
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Long term responses to volcanic eruptions may involve ______ planning to minimize future risks.
Long term responses to volcanic eruptions may involve ______ planning to minimize future risks.
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Mount Pinatubo is located in the ______ and was affected by tectonic activity.
Mount Pinatubo is located in the ______ and was affected by tectonic activity.
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In the Mount Pinatubo eruption, approximately ______ buildings were destroyed.
In the Mount Pinatubo eruption, approximately ______ buildings were destroyed.
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Typhoon Haiyan affected ______ million people, highlighting the vulnerability of communities to natural disasters.
Typhoon Haiyan affected ______ million people, highlighting the vulnerability of communities to natural disasters.
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In the 2015 Gorkha earthquake, around ______ people lost their lives.
In the 2015 Gorkha earthquake, around ______ people lost their lives.
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New land forming on the ocean floor by lava filling the gaps occurs which is known as sea floor ______.
New land forming on the ocean floor by lava filling the gaps occurs which is known as sea floor ______.
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Rift valleys are formed when the lithosphere stretches, causing it to fracture into sets of parallel ______.
Rift valleys are formed when the lithosphere stretches, causing it to fracture into sets of parallel ______.
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A deep sea trench is formed when the more dense oceanic plate ______ underneath the continental plate.
A deep sea trench is formed when the more dense oceanic plate ______ underneath the continental plate.
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The lifted areas of rock are known as ______, whereas the valley itself is known as a graben.
The lifted areas of rock are known as ______, whereas the valley itself is known as a graben.
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When two plates collide, they form a destructive ______.
When two plates collide, they form a destructive ______.
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Hot spots are areas of volcanic activity that are not related to ______ boundaries.
Hot spots are areas of volcanic activity that are not related to ______ boundaries.
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Magma plumes rise vertically due to localized thermal currents created by ______ decay within the Earth's core.
Magma plumes rise vertically due to localized thermal currents created by ______ decay within the Earth's core.
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The process where sediments are pushed upwards during subduction can create ______ mountains.
The process where sediments are pushed upwards during subduction can create ______ mountains.
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Lava can flow quickly or slowly depending on its ______ and silica content.
Lava can flow quickly or slowly depending on its ______ and silica content.
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The rising magma from the Benioff zone forms crescents of submarine ______ along the plate margins.
The rising magma from the Benioff zone forms crescents of submarine ______ along the plate margins.
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Mudflows occur when volcanic material mixes with large amounts of ______.
Mudflows occur when volcanic material mixes with large amounts of ______.
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Volcanic eruptions are always frequent as ______ of them erupt each month.
Volcanic eruptions are always frequent as ______ of them erupt each month.
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Earthquakes at conservative plate margins are caused by pressure building up as plates slide ______ each other.
Earthquakes at conservative plate margins are caused by pressure building up as plates slide ______ each other.
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Nuees ardentes, or pyroclastic flow, is a mixture of superheated gas, ash, and volcanic rock that flows down the side of a volcano at very high ______.
Nuees ardentes, or pyroclastic flow, is a mixture of superheated gas, ash, and volcanic rock that flows down the side of a volcano at very high ______.
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Study Notes
Plate Tectonic Theory
- Earth's lithosphere is divided into tectonic plates.
- These plates move due to convection currents in the asthenosphere.
- Convection currents are driven by heat from radioactive decay in the Earth's core.
- Hot, less dense magma rises, cools, and becomes denser, sinking.
- This creates a continuous loop of rising and sinking magma.
Ridge Push
- At constructive plate margins (divergent boundaries), hot magma rises.
- This creates ocean ridges and heats surrounding rocks.
- Expansion causes the new crust to rise and form slopes.
- Cooling and densification leads to gravity-driven downslope movement.
- This movement separates plates, widening gaps; driven by gravity, hence it's called gravitational sliding.
Slab Pull
- At destructive plate boundaries (convergent boundaries), dense plates sink into the mantle.
- This sinking dense plate pulls the rest of the plate, further driving subduction.
Seafloor Spreading
- Occurs when plates move apart.
- Magma rises to fill the gaps created by the plate movement.
- Magma cools and solidifies, forming new crust.
- This ongoing process widens the plate margin.
- Mid-ocean ridges are a result of new crust formation.
Constructive Plate Margins (Divergent Boundaries)
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Two plates move apart.
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Mantle pressure is released as plates separate.
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Release causes mantle melting into magma.
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Less dense magma rises, erupting as volcanoes.
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Differential plate speeds lead to pressure buildup and earthquakes.
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Oceanic-oceanic divergence leads to underwater volcanoes that create new land via seafloor spreading.
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Continental-continental divergence creates rift valleys.
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Horsts (elevated areas) and grabens (valleys) are formed by diverging plates.
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Mid-ocean ridges are a linear chain of submarine mountains formed by oceanic divergence.
Destructive Plate Margins (Convergent Boundaries)
- Two plates collide.
- Oceanic-continental convergence: Denser oceanic plate subducts under the continental plate (e.g. Peru-Chile Trench).
- Subduction creates deep ocean trenches and fold mountains.
- Sediment is pushed upwards during subduction, forming fold mountains.
- Oceanic-oceanic convergence: Denser plate subducts, creating deep sea trenches and island arcs.
- Continental-continental convergence: Plates are of lower density; no subduction occurs.
- Collisions uplift sediments to form high mountain ranges.
- Shallow focus earthquakes are common.
Conservative Plate Margins (Transform Boundaries)
- Plates slide past each other horizontally.
- No volcanic activity occurs.
- Powerful earthquakes arise from pressure buildup.
Volcanic Hazards
- Magma Plumes: Localized thermal currents generated by concentrated radioactive decay.
- Hot Spots: Occur within plates- unrelated to plate boundaries; magma plumes break through.
Relationship Between Seismicity, Volcanicity, and Plate Tectonics
- Constructive margins: New crust formed; mid-ocean ridges and shallow earthquakes.
- Destructive margins (Oceanic-oceanic): Ocean crust destroyed by subduction; deep ocean trenches and island arcs.
Distribution and Prediction of Volcanic Activity
- Volcanic activity is most common at constructive and destructive margins.
- Hot spots, rift valleys also feature volcanic activity.
- Volcanic Explosivity Index (VEI) measures eruption magnitude (logarithmic scale 0-8).
- Volcanic eruptions are frequent.
Volcanic Hazards
- Lava flows: Slow or fast depending on viscosity (effusive or explosive).
- Lahars (mudflows): Fast-moving mixtures of volcanic material and water.
- Glacial floods: Rapid ice melt due to high temperatures.
- Tephra: Fragmental material ejected.
- Pyroclastic flows: Fast-moving flows of superheated gas, ash, and volcanic rock.
- Acid rain: Volcanic gases combine with water vapor.
- Toxic gases: Gases ejected during eruptions, pose harm to humans.
- Ash fallout: Varying sizes of ejecta; damage vegetation, infrastructure and humans.
Impacts of Volcanic Activity
- Environmental: Ecosystem damage, greenhouse effect increase, climate changes.
- Economic: Business disruption, tourism decline, crop damage, infrastructure reconstruction.
- Social: Casualties, property damage, displacement, mental trauma
Short and Long-Term Responses to Volcanic Activity
- Short term: Evacuations, emergency supplies, mitigation efforts (blocking lava).
- Long term: Early warning systems, land use strategies, adaptation to altered environments.
Case Studies (e.g., Mount Pinatubo, Typhoon Haiyan, Gorkha Earthquake)
- Examples of volcanic and other natural disasters, including associated social, economic, environmental, and political impacts.
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Description
Explore the fundamental concepts of Plate Tectonic Theory, including the movement of the Earth's lithosphere, ridge push, slab pull, and seafloor spreading. Understand how convection currents and gravity influence plate boundaries and geological activity. This quiz encompasses essential geophysical principles crucial for Earth sciences.
