Earthquakes & Volcanos Flashcards
What is the plate tectonics theory?
The lithosphere is divided into several plates known as tectonic plates. the heat from the core causes convection currents in the mantle. This pushes the tectonic plates which float on the mantle
Why is the tectonics theory unproven yet
It is too hot for us humans to be so far down near the magma. We also do not have the equipment to drill down that far
What clues do we have that support the plate tectonics theory
- Earthquakes and volcanos, we believe these happen because of the seismic energy released when tectonic plates interact
- Pangea, scientists belive that all the continents were originally stuck together to make one supercontinent, Pangea, which is shown when the continents look like pieces of a jigsaw puzzle with each other
What is a plate boundary?
A place where two tectonic plates meet
What usually happens on plate boundaries
one plate boundaries there tends to be a lot of seismic activities such as earthquakes and volcanos forming
What is the most noticeable area for seismic activity? why is there more seismic activity than usual
The Ring of Fire is located in between Asia, Oceania, and America. there is a significant amount of seismic activity here because there are lots of plates interacting with each other
What are the layers of earth in order of the inner to outer
Inner core, Outer core, mantle, lithosphere, crust
What are the 4 boundary types?
Constructive
Destructive (continental + oceanic)
Destructive (both continental)
Conservative
What is a constructive plate boundary and what are the characteristics associated with it?
- When two plates move away from each other, magma shoots up.
- Causes volcanos
- Causes weak earthquakes
What is a destructive plate boundary (continental + oceanic) and what are the characteries and what are the characteristics associated with it?
When two plates move towards each other. The oceanic plate is more dense so it will sink under the continental. the area where the two plates collide is called a subduction zone, which is very dangerous.
- causes very dangerous earthquakes
- causes volcanos
What is a destructive plate boundary (both continental) and what are some of the characteristics associated with it
Two plates move towards each other. they’re the same density so the crust rises. this creates a convergence zone (range of mountains).
- Doesn’t cause volcanos
- Causes earthquakes
What is a conservative plate boundary?
Plae boundaries move side by side. this causes friction which is then released by seismic energy
- Doesn’t cause volcanos
- Causes earthquakes
What are the two ways of measuring earthquakes?
Richter scale
Mercalli scale
Describe the Richter scale
The Richter scale is the most popular way of measuring seismic activity. it uses a logarithmic sequence to measure seismic activity on a scale of 1 to 10
Describe the Mercalli scale
The Mercalli scale is a newer way to measure seismic activity. it’s based on observable earthquake damage, whilst this is easier to fill out it is also less valid because everyone has different interpretations, making the Richter scale still the beter option
Christchurch earthquake
FINISH
What is a volcano?
A volcano is a mountain or hill, having a vent or crater in which hot molten magma (Lava) molten rock and ash are erupted onto land
Outline the parts of a volcano and describe what they are
magma chamber
- this is where the molten rock is stored beneath the ground
main vent
- this is the channel through which
magma
travels to reach the Earth’s surface
secondary vent
- some magma may escape through the side of the volcano, particularly if the main vent becomes blocked
crater
- this is found at the top of the volcano, where the magma erupts from
layers of ash and lava
- Volcanic materials deposited on the sides of volcanos during eruptions, eventually building up the volcano and forming a volcanic comb
Parasitic cone
- smaller volcanic cone that forms on the sides of a larger volcano. it’s created by eruptions from secondary vents, drawing magma away from the main vent
What are volcanic bombs, ash, lava, and gas
All are ejected from a volcano during a volcanic eruption
Volcanic bomb
- large rock fragments
Ash
- small particles of rock and glass
Lava
- Magma released out of the earths crust
Volcanic gasses
- Water vapor, Carbon dioxide, and other gases that are released from a volcano, that contribute to atmospheric changes
What are the three states of a volcano and explain them all
Extinct - haven’t erupted in millions of years and isn’t expected to erupt again
Dormant - haven’t erupted for a significant period of time such as a decade but is expected to erupt again in the future
Active - has a recent history of eruptions and is expected to erupt in the near future
What are the two types of volcanos and outline their features
Shield volcano
- Form on a constructive plate boundary
- runny lava with low viscosity
- gently sloping sides + wide base
- Basaltic magma
Composite volcano
- Forms on a destructive plate boundary
- viscous lava
- steep sides + narrow base
- Layers of thick lava + ash on the side of the volcano
Define primary and secondary volcanic hazards
Primary volcanic hazards are the first and direct results of a volcanic eurption
Secondary volcanic hazards the second and knock on effect results of a volcanic eruption
Outline 4 primary hazards of a volcanic eruption
Pyroclastic flows - a mixture of rock fragments, gas, and ash that travels rapidly away from a volcanic vent
Lava - Magma that has risen from the earth’s core, which spews out of a volcano and burns everything in its way
Ashfall - Ash falls all over the ground due to prevailing winds, damaging/getting in the way of infrastructure
Volcanic gases - Gases released from a volcano that have detrimental impacts on the surrounding environment, E.G sulfur dioxide causing acid rain
Outline 4 secondary hazards of a volcanic eruption
Tsunami - Large water displacement from a volcanic eruption causes large waves.
Landslides - Volcanic cones are weaker after a volcanic eruption causing lots of rocks to fall.
Disease - volcanic materials could damage water filtration systems meaning many would get infected
Lahars - mixture of mud and volcanic ash that flows violently after rainfall
