3. Hazardous Environments

Question 1

What is a natural hazard?

Answer 1

An extreme event caused by environmental processes that can cause loss of life, damage to property and disrupt human activity.

Question 2

Types of natural hazards

Answer 2

1. Geological/Tectonic
2. Climatic
3. Biological

Question 3

What is a tropical cyclone?

Answer 3

A weather system of very low pressure formed over tropical seas with strong winds and heavy rainfall.

Known as:
Hurricane (USA)
Cyclone (Australia, Indian Ocean)
Typhoon (East Asia)

Question 4

What is a disaster?

Answer 4

A hazardous geophysical event that affects a vulnerable population.

Question 5

Distribution of tropical storms

Answer 5

Worst in Eastern Asia (China, HK, Vietnam, Philippines)
North America (Florida, Mexico, Caribbean Islands
Some in Indian Ocean, Java Sea (Australia, NZ, Madagascar)
None on equator due to correolis effect (SG, Malaysia)
Anomaly South America (Brazil)

Question 6

Measuring tropical storms

Answer 6

Imager, Sounder, Radar

Saffir-Simpson Scale (1-5)

Question 7

Basaltic lava

Answer 7

Very fluid 
Extremely hot (1200°C)
Fast travelling (retains gas)
Found at CONstructive plate boundaries

Question 8

Properties of andesitic lava

Answer 8

Very viscous (sticky)
Very hot (800°C)
Slow travelling (loses gases quickly and solidifies)
Found at DEstructive plate boundaries

Question 9

Parts of a volcano

Answer 9

Ash cloud
Side vent
Crust
Crater
Lava flow
Main vent
Magma chamber

Question 10

Types of solid lava

Answer 10

Pahoe (ropes)

Ah’ah (jagged/sharp)

Question 11

Pyroclastic flow

Answer 11

Hot moving current of ash and gas
Moves at up to 450mph
Temperature 1000°C
Only happens in andesitic if there is a plug

Question 12

What gases are emitted from volcanoes?

Answer 12

Sulphur, CO2 and cyanide
Hazardous to life
Sometimes no scent and clear/colourless

Question 13

What are ash clouds?

Answer 13

Thrown into air during violent eruption
Roofs often collapse under weight
Can asphyxiate humans and animals

Question 14

What is a lahar?

Answer 14

Mudflow caused by mixture of water and debris
Hot, collects more debris as flows down river valleys
Damage to property

Question 15

Calderas

Answer 15

Large circular volcanic depressions

Magma withdrawn from shallow underground reservoir

Question 16

Measuring volcano explosivity

Answer 16

Volcanic explosivity index (1-7)

Question 17

How do we monitor volcanic activity?

Answer 17

Seismograph (plate turbulence)
Thermometers
Spectrometer (gas emissions)
Geological history
Tilt meters

Question 18

Causes of tropical cyclones

Answer 18

Warm air and sea (27°C)
Within tropics
Moist humid air
Calm winds
Low wind sheer

Question 19

Measuring earthquakes

Answer 19

Richter scale (0-9)
Mercalli scale (I-XII)

Question 20

Layers of the earth

Answer 20

Crust
Mantle
Outer core
Inner core

Question 21

Constructive/divergent plate boundary

Answer 21

Ridge push forces plates apart
Magma rises to fill gap where crack is
Forms submarine volcanos
eg East African Rise (Kenya/Ethiopia)

Question 22

Destructive/convergent plate boundary

Answer 22

Plates of oceanic crust move towards continental crust
Friction creates earthquakes
eg Nazca plate moving towards S American plate

Question 23

Collision plate boundary

Answer 23

Two continental plates meet head on
Neither sink, land buckled up
Fold mountains formed
Earthquakes

Question 24

Conservative plate boundary

Answer 24

Plates slide past each other at different directions or speed
Pressure built up, lots of friction
Destructive earthquakes
eg San Andreas plate in California

Question 25

Volcanic hotspots

Answer 25

Plate moves over unusually hot part of mantle
As plates move, volcanoes form
eg Hawai’i

Question 26

What are some factors affecting risk from hazards?

Answer 26

Hazard (Duration, magnitude, frequency, severity)
Vulnerable (Population, LIC, pool, old, population density)
Preparedness (Supplies, warnings, prediction, aid)

Question 27

Why do people continue to live in hazardous areas?

Answer 27

Fertile land (productive agriculture, eg Japan, Italy)
Lack of education (misinformed, disregard, eg Indonesia)
Not enough money (can’t afford to move, eg India)
Need jobs (well-paid jobs, eg Japan)
Religious beliefs (goddess, eg Hawai’i)

Question 28

What are some types of attitude towards hazards?

Answer 28

Ill-informed (does not know)
Denial (refuses to acknowledge hazard)
Accepting (knows hazard)
Adaptive (changes to accommodate hazard)
Fatalistic (doesn’t mind dying)