Week 1, A Global and Canadian Outlook on Natural Disasters

Question 1

Internal heat is primarily generated from

Answer 1

ongoing decay of naturally occurring radioactive elements that have been present in the earth since the beginning.

Question 2

The frequency of weather related disasters is

Answer 2

increasing world wide.

Question 3

The frequency of geologic disasters is

Answer 3

stable.

Question 4

Why is the economic cost of natural disasters increasing rapidly?

Answer 4

Increasing population

Vulnerable infrastructure

Question 5

Why do developed countries have fewer casualties but higher economic costs?

Answer 5

More money for mitigation

Extensive and expensive infrastructure

Question 6

Rheology

Answer 6

How a material strains under stress.

Question 7

Stress

Answer 7

Force per area

Question 8

Compression

Answer 8

Pressure perpendicular to surface

Question 9

Tension

Answer 9

Perpendicular to surface

Extension

Question 10

Shear

Answer 10

Parallel to surface

Distortion

Question 11

Strain

Answer 11

Relative deformation under stress.

When you apply stress to an area it will strain.

Question 12

What do liquids do under stress?

Answer 12

They flow

Question 13

Elastic Strain

Answer 13

Deformation is recoverable

Question 14

Ductile Strain

Answer 14

Deformation is permanent

Question 15

Brittle Strain

Answer 15

Rigid object fractures

Like a Kit Kat

Question 16

Plastic Strain

Answer 16

Flows like high viscosity fluid

Like a Mars Bar

Question 17

The Earth’s crust is ____ while the mantle undergoes _____ ______.

Answer 17

The Earth’s crust is brittle while the mantle undergoes plastic flow.

Question 18

What does rheology depend on?

Answer 18

Temperature and pressure

Question 19

Why does oceanic crust tend to sink and subduct below continental crust?

Answer 19

Because it is heavier.

Question 20

Solid/melted state depends on…?

Answer 20

Pressure: Increases approximately linearly inward due to overburden weight

Temperature: Increases non-linearly inward due to heat from radioactive decay

Composition: Different materials melt at different pressure/temperature combinations

Question 21

Isostacy

Answer 21

Buoyancy

Gravitational equilibrium whereby lithosphere “floats” on denser, deformable, asthenosphere at an elevation dependant on its thickness and density.

Topography

Like icebergs, the higher they extend above water, the higher they extend below water.

We can observe this in mountain ranges.

Question 22

Isostatic Adjustment

Answer 22

Post Glacial Rebound

Glacier weight causes subsidence

Crust rebounds when ice is removed

Question 23

Seismology

Answer 23

Using earthquakes to study the earth’s interior

Question 24

Causes of earthquakes

Answer 24

Volcanic Activity
Oil and Gas Production
Meteorite Impacts
Mining
Landslides
Caldera Collapses 
Explosions
Glaciers

Question 25

Faults

Answer 25

A fracture in the earth across which two sides move relative to each other.

Complex, irregular surfaces where interlocking rock is held together by friction.

Question 26

Fault Rupture

Answer 26

Elastic Rebound Theory

• Fault is locked by friction
• Relative motion across fault accommodated as elastic strain
• Stress exceeds friction, causes rupture, releases energy as seismic waves

Question 27

Hypocentre

Answer 27

Focus

Point where rupture initiated

Question 28

Epicentre

Answer 28

Point directly above hypocentre on Earth’s surface

Question 29

Strike-slip

Answer 29

Transform

Horizontal Motion

Question 30

Dip-slip

Answer 30

Vertical Motion

Normal and reverse faults