Plate Boundaries
What are the two types of tectonic plate?
Oceanic and continental
Why is an LIC more at risk of tectonic hazards?
- Less money to prepare eg. education drills
- Not as easy access to medical supplies
- Buildings can't be made 'earthquake proof'
- If tectonic hazards are frequent, they are unable to recover fully
On what scale do we hear earthquakes measured on the news?
Richter scale
What type of volcano forms on a constructive plate margin?
A shield volcano.
Composite volcanoes form at destructive plate margins.
What is the difference between magma and lava?
Both are molten rock - magma is below the Earth's surface, lava above the Earth's surface
What are the 4 types of plate boundaries?
Collision, Constructive, Conservative, Destructive
Why do some people live near volcanoes?
- Jobs
- It's where they've always lived
- To stay near family and friends
- Poverty means that they can't afford to move away
On what scale is it now recommended that earthquakes should be measured on?
Moment Magnitude
What do volcanoes emit?
Ash, molten rock and gases (carbon dioxide, sulphur dioxide etc.)
On what type of plate boundary is the Himalayas?
A collision plate boundary
On how many types of plate boundaries would earthquakes occur?
What is the difference between oceanic and continental crust?
Oceanic Crust is older, denser and thinner.
Continental Crust is younger, lighter and thicker.
What other hazards can earthquakes trigger?
Tsunamis and landslides
What can be done to limit the impacts of volcanic eruptions?
- Plan for eruptions, eg. create evacuation routes/drills etc.
- Monitor the volcano
- Create exclusion zones (like in Montserrat)
- Direct lava flow
Define the 'focus' of an earthquake
Focus is the point of release of seismic energy in the earth's crust (below the ground) during earthquakes
On which two plate boundaries do volcanoes occur?
Constructive, Destructive
Describe what happens at a collision plate boundary.
Two plates, both made up of continental crust, push towards each other. As they push against each other, as they are both the same density, they start to crumple in an upwards direction, folding together, creating fold mountains.
Where exactly did the Japan 2011 earthquake occur?
The epicentre (centre of the earthquake on the top of the earth’s crust) was 130km east of Sendai, a city in north east Japan. It had a focus (centre of the earthquake beneath the ground) of 24km deep.
Name 2 primary impacts of volcanic eruptions
- Buildings and roads are destroyed
- People and animals are injured or killed
- Crops are damaged or destroyed
- Water supplies become contaminated
Define the 'epicentre' of the earthquake
The point on the Earth's surface where the seismic waves of an earthquake emanate from
Around which tectonic plate would you find most of the worlds' volcanoes?
Pacific
"Ring of Fire"
Describe what happens at a conservative plate boundary.
Two plates are moving alongside each other in one of two ways.
1. The plates are moving in the same direction at different speeds.
2. The plates are moving alongside each other in opposite directions.
Both lead to the plates getting stuck on each other and this leads to a build-up of pressure. Eventually, the plates will jolt past each other causing earthquakes.
How does a tsunami form?
A tsunami forms when an earthquake occurs under the sea. The jolt of the tectonic plates causes water to be displaced. This displaced water travels towards land, gaining speed and energy the further it travels. Just before a tsunami hits land, the sea will appear to retreat, as the wave builds up in shallower water, giving the tsunami wave height. This wave then collapses and spreads inland.
Name 3 secondary impacts of a volcanic eruption
- Fires started by lava and pyroclastic flows
- Mudflows are created when volcanic eruption material mixes with water, causing further destruction
- Mental health support needed for families who lost loved ones.
- People are left homeless
- Shortage of food because crops are damaged.
- Unemployment because businesses close if their buildings were destroyed.
Which conservative plate boundary is predicted to cause a large earthquake in the next 10 years?
San Andreas Fault, USA