Midterm #1 Content

Question 1

What’s the most frequent natural hazard in Canada?

Answer 1

Floods

Question 2

Differentiate between a hazard, disaster and catastrophe

Answer 2

Hazard < disaster < catastrophe.
Hazard: natural event that is a potential threat to human life/property.
Disaster: hazardous event that occurs over a limited time in a defined area
Catastrophe: massive disaster that requires significant amount of money or time to recover

Question 3

Uniformitarianism: “The ______ is the key to the _____.”

Answer 3

present; past

Question 4

Prediction vs. forecast

Answer 4

Prediction: specific date, time, and magnitude of event
Forecast: range of probability for the event
Some hazards can be predicted; most can be forecasted.

Question 5

What is the internal structure of earth, from outside to in?

Answer 5

Crust > Lithosphere > AsthenosphereW

Question 6

What are the types of plate boundaries?

Answer 6

Divergent: Ocean spreading.
Convergent (subduction): ocean-continent. Ocean plate sinks beneath continental plate.
Convergent (subduction): ocean-ocean. Ocean plate sinks beneath other ocean plate.
Convergent (collision): continent-continent. They compress.
Transform (ocean-ocean or continent-continent): Plates slide.

Question 7

What created the Himalayas?

Answer 7

India crashing into China

Question 8

What are the hazards of different plate tectonics/boundaries?

Answer 8

Divergent = earthquakes and volcanoes
Transform = earthquakes
Convergent subduction = makes volcanoes and earthquakes
Convergent collision = makes mountains and earthquakes

Question 9

What is faulting?

Answer 9

Process of fault rupture. Sliding one rough board past another.

Question 10

Differentiate between a normal, reverse, and strike dip-slip fault.

Answer 10

Normal: Hanging wall moves DOWN relative to footwall. TENSIONAL stress.
Reverse: Hanging wall moves UP relative to foot wall. COMPRESSIONAL stress.
Strike: Crust moves. SHEARING stress.

Question 11

What does the Richter scale measure?

Answer 11

Earthquake magnitude.
Strong = 6-6.9, Major = 7-7.9, Great = 8+

Question 12

What plate boundary is the site of the largest earthquakes?

Answer 12

Subduction zones

Question 13

What natural hazard is most closely linked with earthquakes?

Answer 13

Landslides

Question 14

How do humans contribute to causing earthquakes?

Answer 14

• Loading earth’s crust, like building a dam or reservoir, adding weight or creating new faults/lubricating old ones
• Injecting liquid waste deep into the ground through disposal wells, creating pressure on faults
• Creating underground nuclear explosions

Question 15

Approximately 2/3 of active volcanoes are within the ______ __ _____.

Answer 15

Ring of Fire

Question 16

What is the ring of fire?

Answer 16

Surrounds the Pacific Ocean basin.
Subduction zones are responsible for this.
A large, continuous, horseshoe shape of volcanoes, both under water and above ground

Question 17

What have been some of the biggest disasters in the ring of fire?

Answer 17

• Mount St Helena, Mount Rainer, Mount Lassen in the US
• Mount Fuji, Mount Uzden in Japan

Question 18

Magma properties are describes by _______ ________ and amount of ________ ________.

Answer 18

silica content; dissolved gases

Question 19

What do viscosity and volatile content mean regarding magma?

Answer 19

Viscosity: resistance to flow
Volatile Content: Determines how explosive the eruption will be

Question 20

What are stratovolcanoes?

Answer 20

Big cone shaped mountains. High viscosity magma. Lava does not flow far, resulting in steep sides (cone!). Can be extremely explosive; responsible for 80% of eruptions. Common in the Ring of Fire.

Question 21

What are lava domes?

Answer 21

Small dome with steep sides. Made from highly viscous magma; highly explosive eruptions. Common in the Ring of Fire.

Question 22

What are shield volcanoes?

Answer 22

LARGEST volcanoes in the world. Wider than they are tall. low viscosity, low volatile content. Gently flowing lava, generally non-explosive.

Question 23

What are cinder cones?

Answer 23

Cone shaped with a summit crater. Low-intermediate explosivity. AKA Scoria cones.

Question 24

What are Continental Caldera?

Answer 24

Large summit depression. Collapse of the land surface or volcanic edifice. VIOLENT explosions. They form by explosion of a stratovolcano, which collapses.

Question 25

How do earthquakes cause a tsunami?

Answer 25

1) Seafloor movement (common)
2) Triggering a landslide

Question 25

How big must an earthquake be to trigger a tsunami?

Answer 25

M = 7 or greater

Question 26

What is the four stage process of a tsunami?

Answer 26

1) Earthquake uplifts or downshifts the seafloor
2) Tsunami moves rapidly in deep ocean
3) Tsunami nears land, loses speed, gains height
4) Tsunami moves inland, destroying everything in its path

Question 27

What was the world’s largest earthquake and therefore tsunami?

Answer 27

2004 Indonesian Tsunami
Most lethal in recorded history
Education (lack of) was a major reason for so many deaths
Killed people on both sides of indian ocean

Question 28

How can we minimize the tsunami hazard?

Answer 28

• Detection and warning
• Structural control
• Land use
• Run maps
• Probability analysis

Question 29

What are the evacuation stages for a tsunami in British Columbia?

Answer 29

1) Evacuation order; leave the area.
2) Evacuation alert; be ready to leave on short notice.
3) Declaration of local state of emergency
4) Evacuation rescinded; all good

Question 30

Differentiate between tsunami warning, advisory, and watch

Answer 30

Warning > Advisory > Watch.
Warning is the highest level. Imminent threat.
Advisory is the second highest level. Potential threat.
Watch is the third highest level. No confirmation of threat, but maybe.

Question 31

What are the 3 types of landslides?

Answer 31

Falling: free fall of earth material
Sliding: movement of material as a coherent block
Flow: movement of unconsolidated material; very slow

Question 32

What are the two common types of avalanches?

Answer 32

1) Loose snow
2) Slab avalanches

Question 33

How can landslides be prevented?

Answer 33

1) Drainage control
3) Grading; increases slope stability (making a soil cement wall)
3) Slope supports; retaining wallsW

Question 34

What was the event of La Conchita?

Answer 34

BIG LANDSLIDE

Question 35

What are the three tpyes of magma, based on silica content? (Low to high)

Answer 35

Basaltic, andesitic, rhyolitic (BAR)