Hazardous Earth Flashcards
What is the Crust?
The thin layer of solid rock that cases the mantle beneath
Types of crust?
Oceanic and Continental
How thick is oceanic crust?
6-8 km thick
How thick is continental crust?
30-50 km thick
What is oceanic crust made from?
Basalt (Dense Igneous Rock)
What is continental crust made from?
Granite (Low Density Igneous Rock)
What is the lithosphere?
A layer consisting of the crust and upper mantle
What is the asthenosphere?
The top layer of the mantle
What is the physical state of the outer core?
Liquid
What is the physical state of the mantle?
A viscous fluid
What physical state is the inner core?
Solid
Where do convection currents occur?
Outer Core and Mantle
What is a convection current?
The process by which heat is transferred from the core to mantle and mantle to crust. Hotter parts of the mantle/core rise to the top of their layer. Then, they cool and sink back down.
List the different sections of the Earth from the centre outwards.
Inner Core, Outer Core, Lower Mantle, Upper Mantle (Lithosphere, Asthenosphere) and Crust (Lithosphere)
What is the mantle made from?
Peridotite
What is the outer core made from?
Iron and Nickel
What process heats the earth from within?
Radioactive decay of elements like Uranium and Thorium in the core and mantle.
What is a conservative plate boundary?
Two plates sliding past one another.
What does a conservative plate boundary cause?
- Destructive earthquakes, magnitude 8.5
- Small daily tremors
- No volcanoes
What is a divergent plate boundary?
When two plates move apart
What does a divergent boundary cause?
- Small earthquakes, magnitude 5-6
- Not very explosive or dangerous volcanoes
- Occurs in fissures (cracks in crust)
- Erupts basalt lava at 1200 degrees
What is a convergent plate boundary?
When one plate is pulled under the other
What does a convergent plate boundary cause?
- Very destructive earthquakes, magnitude 9.5
- Tsunamis
- Very explosive, destructive, steep, cone-shaped volcanoes
What is a collision zone boundary?
When two plates collide, forcing both upwards
What does a collision zone boundary cause?
- Destructive earthquakes, magnitude 9.0
- Landslides
- Volcanoes are very rare
Name an example of a conservative plate boundary
San Andreas Fault
Name an example of a divergent plate boundary
Iceland on the mid-Atlantic ridge
Name an example of a convergent plate boundary
Andes Mountains in Peru and Chile
Name an example of a collision zone boundary
Himalayas
Name the four types of plate boundary
Conservative, Divergent, Convergent and a Collision Zone
How do convection currents help create volcanoes?
When plates move apart, a void is created, which is filled with mantle that moves upwards due to the earth’s convection currents.
Name a section of the earth with the youngest crust
Middle of the Atlantic
Give 2 contrasting example of countries affected by severe earthquakes (case studies)
Haiti and New Zealand
When a tsunami nears the coast what happens to its speed and height?
It slows down, but its height increases dramatically
What type of scale is the Richter scale?
A logarithmic scale
What is the point where earthquakes start called?
The Focus
What is the point on the ground directly above the focus called?
The Epicentre
What happens when the focus of an earthquake is shallower?
A shallower focus means a more destructive earthquake
What piece of equipment is used to measure an earthquake’s power?
A seismometer
What are the smaller earthquakes called that follow a main one?
Aftershocks
What is the hot, rising material in a convection current called?
A magma plume
What are the two main factors in the severity of an earthquake?
Magnitude of earthquake and whether the affected country is an LEDC or an MEDC.
What was the magnitude of the 2010 Haiti earthquake?
7.0
What were the shock magnitudes in Haiti’s earthquake?
up to magnitude 6.0
Why did so many people die in the 2010 Haiti earthquake?
- Poor architecture
- Unprepared
- People were bribed to sign of buildings despite them not meeting regulations
Primary effects of Haiti Earthquake
- 230,000 deaths
- 180,000 homes destroyed by ground shaking
- Devastated the capital, Port-au-Prince
- Infrastructure destroyed
Long term effects of Haiti Earthquake
- 1.5 million people homeless
- 1100 squalid camps with basic water and sanitation
- Cholera outbreak killed several hundred
Responses to Haiti Earthquake
International aid sent to Haiti in the form of:
- Food
- Water
- Medical supplies
- Temporary shelters
How deep was the Haiti Earthquake’s focus?
13 km deep on a conservative boundary
Where was the Haiti Earthquake’s epicentre?
25 km west of Port-au-Prince
What was the magnitude of the 1995 earthquake in Kobe, Japan?
Magnitude 7.2
Primary effects of Kobe Earthquake
- 6434 people dead
- 40,000 injured
- Gas mains ruptured
- Water pipes fractured
- Railway lines buckled.
Secondary effects of Kobe Earthquake
- 300,000 homeless
- 2 million without electricity
- 1 million without clean water for 10 days
- $220 billion damage
Responses to Kobe earthquake
- Everyone looked for survivors
- Major retailers provided supplies for people
- Motorola allowed free mobile phone connections
- Railways 80% operational within a month
- Most roads were fixed within half a year
- Stricter building regulations put in place
- Earthquake drills practised annually
How did being an MEDC enable Japan to help Kobe reover rather quickly?
They already had a lot of infrastructure in place in case of disasters like this. The government didn’t require as much international aid as Japan itself in very wealthy.
How deep was the 1995 Kobe Earthquake’s focus?
17.6 km
Where was the Kobe Earthquake’s epicentre?
20 km southwest of Kobe
What are the three types of Volcano?
- Shield volcano
- Composite/Strato volcano
- Super volcano
How an you describe a volcano’s activity?
- Active (frequent eruptions)
- Dormant (temporarily inactive but not fully extinct)
- Extinct (Never likely to erupt again)
What type of boundary are shield volcanoes found?
Constructive boundaries
What type of boundary are composite volcanoes found?
Destructive boundaries
What are the characteristics of a shield volcano?
- Low with gently sloping sides
- Formed by eruptions of thin, runny lava
- Frequent, gentle eruptions
What are the characteristics of a composite volcano?
- Made up of alternating layers of ash and lava
- Eruptions can be pyroclastic flow instead of lava
- Pyroclastic flow can roll down the sides of the volanop at very high speeds and with temperatures over 400°C
What is pyroclastic flow?
A mixture of hot steam, ash, rock and dust.
What is a supervolcano?
It is a volcano on a massive scale.
What are the characteristics of a supervolcano?
- It erupts at least 1000 cubic km of material, whereas a large volcano erupts 1 cubic km.
- It forms a depression called a caldera, whereas a volcano produces a cone shape
- Often has a higher ridge of land around it
- Eruptions are hundreds of thousands of years apart
