Flashcards in Tectonic hazards Deck (29):
The Earth's surface is separated into what?
What are the different layers of the Earth?
The inner core, outer core, mantle, crust.
What is the inner core?
A ball of solid iron and nickel.
What is the outer core?
A layer of liquid iron and nickel.
Tectonic plates are made of two types of crust, what are they?
Continental and oceanic.
What is continental crust?
It's thicker (30-50km) and less dense.
What is oceanic crust?
It's thinner (5-10km) and more dense.
What causes plates to move?
The plates are moving due to convection currents in the mantle underneath the crust.
The places where plates meet are called what?
Plate margins or plate boundaries.
There are 4 types of plate margin, what are they called?
Destructive, constructive and conservative margins as well as collision zones.
What happens at destructive margins?
An oceanic plate meets a continental plate, the denser oceanic plate is forced down into the mantle and destroyed. This often creates volcanoes & ocean trenches.
What happens at conservative margins?
Two plates are moving sideways past each other, or moving in the same direction but at different speeds. This causes earthquakes.
What happens at constructive margins?
Two plates are moving away from each other. Magma rises from the mantle to fill the gap and cools, creating new crust.
What happens at collision zones?
Where two continental plates meet, the plates collide, and the ground is folded and forced upwards to create mountain ranges.
What are pyroclastic flows?
Super-heated currents of gas, ash and rock.
What is the focus?
The point in the Earth where the earthquake starts.
What is the epicentre?
The point on the Earth's surface straight above the focus.
Earthquakes are caused by what?
Tension that builds up at the plate margins.
How are earthquakes measured?
Using the moment magnitude scale: it measures the amount of energy released by an earthquake.
What are the primary effects of an earthquake?
-Buildings and bridges collapse, homes destroyed
-Roads/railways/airports are damaged
-Electricity/gas/water pipes damaged, communication networks cut off
What are the secondary effects of an earthquake?
-They can trigger landslides/tsunamis
-Leaking gas can start fires
-People left homeless
-Lack of sanitation
-Repairs are expensive
What are the immediate responses to an earthquake?
-Rescue people trapped
-Put out fires
-Provide temporary supplies of water, food, electricity and gas
-Tech companies set up disaster response tools, people an confirm safety and damage can be recorded
What are the long-term responses to an earthquake?
-Re-house people who have lost homes
-Make buildings more resistant to earthquakes
-Reconnect broken electricity/water/gas/communication networks
What are the primary effects of a volcanic eruptions?
-Buildings/roads destroyed by lava flow
-People/animals are injured/killed
-Water supplies contaminated
What are the secondary effects of a volcanic eruption?
-Mudflows and landslides cause more death and destruction
-Flooding can be caused by hot rock/ash/gas melting ice/snow at the top of the volcano. Ask can clog up rivers
-Ash makes fields more fertile
What are the immediate responses to a volcanic eruption?
-Provide food, drink and shelter
-Rescue trapped people
-Tech companies set up disaster response tools allowing damage to be recorded and people to confirm their safety
What are the long-term responses to a volcanic eruption?
-Repair and rebuild
-Update monitoring and evacuation plans
Why do people choose to live close to volcanoes/areas vulnerable to earthquakes?
-The soil is fertile due to ash, good for growing crops
-People have lived there all their lives
-They're employed in the area