WA1 - Living with tectonic Hazards

Question 1

Natural Hazard

Answer 1

A natural hazard is a perceived natural event that has the potential to threaten both life and property

Question 2

Natural Event

Answer 2

• A natural event is a naturally occurring event that threatens human lives and causes damage to property
• A natural event in an uninhabited place becomes a hazard in a populated one

Question 3

Natural Disaster

Answer 3

• A natural Disaster is the realisation of an hazard when it causes a significant impact on a vulnerable population
• A disaster is a sudden , calamitous event that causes serious disruption of the function of a community or a society causing widespread human and material damage .

Question 4

Recording of a Disaster , criteria

Answer 4

• 10 or more people killed ,
• At least 100 affected
• A deceleration of a state of emergency by the relevant government
• A request by the national government for international assistance

Question 5

Inner Core

Answer 5

1200KM
5000-7000
Solid State
Iron and Nickel , known as the NiFe layer

Question 6

Outer Core

Answer 6

2300KM
3000-4000 *c
Liquid
Iron and Nickel in the Molten Layer

Question 7

Lower Mantle

Answer 7

2900KM
800-3000*C
Solid and Molten state of Iron and MAGNESIUM

Question 8

Upper Mantle + Aesthenosphere

Answer 8

150-250KM
less than 800*c
Liquid and Solid of IRON AND MAGNESIUM

Question 9

Oceanic Crust

Answer 9

Thinner but denser than Continental Crust
5-8KM
Made up of basalt less than 200 Million years old

Question 10

Continental Crust

Answer 10

Thicker but less than Continental Crust
35-70Km
Granite
4 Billion years old and found under shallow seas

Question 11

How do tectonic Plates move

Answer 11

Tremendous heat found in Earth’s core causes rocks
in mantle to melt and become magma.
● Liquid mantle material, called magma, is intensely
heated and expands, rising up.
● Rising and spreading lava pulls the plates apart,
causing them to diverge as they are dragged along
and move away from each other.
● Then the magma cools and sinks, pulling the plates along.
● The sinking mantle material heats up again as it nears the core, creating a convection current and causing the whole process to
repeat.

Question 12

Explain Oceanic-Oceanic Convergence

Answer 12

Associated landforms -> Oceanic trench and island arcs
Process -> Vulcanizing and subduction

The denser oceanic plate is subducted under the less dense plate which bends downward into the mantle , forming a trench . During the subduction , the crust mantle melts becoming magma , which gains heat and expands upwards and the magma cools and forms an island arc

After the subduction is complete , the plates are melted and destroyed , new plates are formed at divergent plate boundaries

Question 13

What is a trench

Answer 13

A trench is a long narrow depression in the sea floor

Question 14

Explain Continental-continental convergence

Answer 14

Associated Land forms -> Fold mountains by the process of folding

When two continental plates converge , they do not subduct due to their similar densities and hence push into one another , reason is its thickness
-The resultant compression force creates immense pressure which causes the rocks to buckle and fold-> This forming fold mountains

Question 15

Explain Oceanic - Continental Convergence

Answer 15

Associated Landforms -> Oceanic trenches , Fold mountains , volcanoes

Oceanic plates subduct under the Continental plates as they are denser .

The downward movement of the plate dips into the mantle and may produce a deep oceanic trench , the downward movement of the oceanic plate may cause the melting of the mantle material above it , which produces magma that escapes through any leaks or fractures and when it escapes through the vents onto the surface , a volcano is formed

Question 16

Explain Oceanic-Oceanic divergence

Answer 16

Associated landforms -> Mid oceanic ridges , and volcanic islands

Process - Sea floor spreading

As the two plates move apart they form fractures @ the boundary where magma then rises up from the zone of divergence cools and solidifies to form new sea floor known as a mid oceanic ridge , as the plates move apart the ridges move away and new ridges are formed , the youngest ridge is closest to the zone of divergence while the older ones are more spread apart

At various points in the mid oceanic ridge magma may build up and solidify to form undersea volcanoes that eventually grow above sea level to form volcanic islands

Question 17

Sea floor map

Answer 17

Darker -> Normal polarity
Lighter -> Reversed polarity
Newer sea floor is closer to the mid oceanic ridge

Question 18

Continental - Continental plate divergence

Answer 18

Associated landforms -> Rift valleys and block mountains + volcanoes