Tectonic Hazards (volcanoes And Earthquakes) Y9 Flashcards
4 Layers of the earth from inside to outside
Inner core
Outer core
Mantle
Crust
Layers of earth from least dense to most dense
Continental crust
oceanic crust
Upper mantle
Lower mantle
Outer core
Inner core
Difference between continental and oceanic crust
Continental- thicker(30-50km) and less dense
Oceanus - thinner (7km) and denser
Temperature of inner core
6000 Celsius
What is lithosphere?
All of crust + upper mantle
What landforms do constructive margins make?
Volcanoes and Earthquakes
What landforms do destructive margins make?
Volcanoes and earthquakes
What landforms do conservative margins make?
Earthquake
What landforms do collision margins make?
Earthquakes
How are constructive margins formed?
Two plates are diverging above the upward plume of a convection cell. Magma rises through the gap between the two plates resulting in volcanoes.
Eruptions and earthalong constructive margin tend to be relatively gentle.
How are destructive margins formed?
When two plates, one oceanic crust, one continental crust, are converging. When they meet the oceanic crust dives beneath the continental plate because it’s denser. Known as SUBDUCTION .
What can destructive margins form and how?
Continental can buckle upwards creating fold mountains.
Oceanic can get stuck due to friction leading to build up in pressure -earthquakes. Friction also generates heat causing oceanic crust to melt which creates extra magma which rises to surface resulting in violent eruptions
What can constructive margins form and how
Volcanoes-Magma rises through the gap between the two plates resulting in volcanoes.
Eruptions and earthquakes constructive margin tend to be relatively gentle.
How are collision margins formed?
When two continental plates converge. Because neither plate is denser subduction does not occur. Both plates buckle upwards creating a range of fold mountains.
What can form at collision margins and how?
NO volcanoes because there is no rising magma.
But very powerful earthquakes can occur
How are conservative margins formed ?
When two plates move alongside each other in opposite or the same direction. This creates pressure -earthquakes
What do conservative margins form and how?
When two plates move alongside each other in opposite or the same direction. This creates pressure -earthquakes
Qualities of shield volcano(7)
Basic lava
1200 degrees Celsius
Frequent gentle, eruptions
Faster-moving lava flows
Lava travels far from vent before solidifying
Constructive margins
Low viscosity (runny)
Qualities of stratovolcano(9)
High viscosity (sticky)
Narrow base, steep sides
Ash clouds
Acidic lava
800degrees Celsius
Composite cone(another name )
Destructive margins
Infrequent, explosive eruptions
Lava gets stuck in vents leading to a build up of pressure
Which volcano has low viscosity lava and what does it mean
Shield volcano-runny
Which volcano has a narrow base and steep sides?
Stratovolcano
Which volcano has infrequent explosive eruptions
Stratovolcano
How hot is a stratovolcanoes lava
800 degrees Celsius
How hot is a shield volcanoes lava
1200 degrees Celsius
Which volcano has high viscosity lava and what does it mean
Stratovolcano-sticky
Which volcano has frequent, gentle (effusive) eruptions
Shield volcano
What volcanoes lava moves faster?
Shield volcano
Broad base, gentle slopes which volcano
Shield volcano
Which volcano has acidic lava
Stratovolcano
Which volcano has basic lava
Shield volcano
What volcano produces ash clouds
Stratovolcano
Which volcano is on destructive margins
Stratovolcano
Which volcano has lava that travels far from vent before solidifying
Shield volcano
Which volcano has slow moving lava that solidifies close to the vent and can sometimes get stuck, leading to a buildup of pressure?
Stratovolcano
Which volcano is also called a composite cone
Stratovolcano
What volcano is a Hawaiian hotspot
Shield volcano
Which volcano is in Arenal, Costa Rica
Stratovolcano
What is a magma chamber
A reservoir of molten rock within the crust below a volcano.
What is a cone
The volcano itself is called a cone
What is a parasitic cone
A smaller cone that develops on the side of a main cone
What is a crater
A depression at the summit of the volcano
What is a vent
The ‘pipe’ that connects the magma chamber to the crater.
Definition of volcano
An opening in the earths crust from which molten rock and gas is ejected into the atmosphere and onto the earths surface. A very large crater called a Caldera
What is the epicentre
The point on the earth’s surface directly above the focus, in theory shaking will be strongest here
What is the focus?
The point underground where the plates slip and from where the seismic waves radiate outwards
What are aftershocks
Smaller earthquakes that occur hours, days or weeks and months following the main event. Caused by plates slipping a little more as they settle down
What is a fault line
A fracture in the rock at a plate margin where pressure builds up if the moving plates stick
What are seismic waves
Energy waves that radiate out from the focus and cause the ground to shake. Primary waves stretch and compress the ground, whilst secondary waves shake it from side to side
What is magnitude
The higher the magnitude of an earthquake the more energy that is released and the greater the potential for damage to buildings and therefore deaths/injuries to people
Factors affecting earthquake impacts(7)
Magnitude
Geology(soft rocks etc)
Population density
Distance from epicentre
Time of day
Depth of focus
Level of development
What is the mercalli scale
It assesses the impacts of an earthquake by looking at the damages e.g such as structural damages to buildings.
What do scientists use to measure earthquakes energy
Scismograph
What is the Richter scale
It assesses amount of energy released by earthquake and intensity of shaking.
What is the only primary hazard for earthquakes
Ground shaking and displacement
Which way is longitude
Vertical
Which way is latitude
Horizontal
How do you calculate mean
Add all up then divide by amount of numbers
How do you calculate mode
Value appears most often
How do you calculate median
Order values and find middle
How do you calculate range
Biggest -smallest
