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Flashcards in Tectonic & Climatic hazards Deck (29)
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1

Plate Boundaries

Constructive
Conservative
Destructive
Collision

2

Definition of a natural hazards

A natural hazard is an extreme natural event or process that causes loss of life and/or extreme damage to property and creates severe disruption to human activities

3

Conservative/Transform plate boundary

Plates slide past each other
Causes pressure + stress to build up
A quick release of energy causes sudden movements which create earthquakes

4

Constructive plate boundary

Caused by convectional currents in the mantle
Plates move away from each other
Magma then rises and causes volcanic eruptions

5

Destructive plate boundary

Convectional currents in mantle
Oceanic & continental plates move together
Pressure builds up and the thinner oceanic plate gets subducted and melts
Causes volcanic eruptions as magma then rises

6

Collision plate boundaries

Convectional currents in the mantle
2 continental plates of the same density and strength move towards each other
Pressure builds up causing buckling to form mountains + volcanoes

7

How to predict volcanic eruptions

Gas measurements - SO2 & CO2 levels increase
Seismic readings
Satellite imagery - measures 'bulges' as magma moves up the volcanoes
Temperature/acidity of soil - increases

8

Causes of Nevada del Ruiz - Colombia

Dormant for 150 years
Destructive Plate Boundary
Nazca plate (oceanic) subducted under south American plate (continental)

9

Effects of Nevada del Ruiz - Colombia

Pyroclastic flow (20 m. cubic metres of hot ash, rock +gas)
Lava flows
Huge Lahar (40m thick + moved at 50 km/h)
23,00 deaths
5000 injured
5000 homes destroyed

10

Secondary effects of Nevada del Ruiz - Colombia

Hot lahars served as breeding ground for bacteria + many with minor cuts got infected & died
Blocked roads and people couldn't be reached
Cost Colombia 20% of their GDP (7.7 bil.)

11

Responses to Nevada del Ruiz- Colombia

No evacuation
Inadequate rescue + emergency services
Locals had ignored warnings from American volcanologists ( no Colombian equipment)

12

Why there were inadequate response

LEDC
During the night ( hard rescue)
Large population
Roads + bridges destroyed

13

Causes of Mount Etna - Italy (2002)

Strato volcano
Destructive plate boundary
African plate slipped under Eurasian

14

Effects of Mount Etna - Italy (2002)

1,000 people evacuated
100 homes destroyed
Forests destroyed
Tourism effected
2 channels dug to divert lava
Tax breaks for villagers
$8 m. Given to the town
Loss of agricultural land
Columns of ash deposited material in Libya

15

Formation of Hurricane Katrina

Formed in the Gulf of Mexico off the coast of Florida in August 2005

27*C
60m deep
Convection
Circular pattern - rotation of Earth

16

Before Hurricane Katrina

Satellite monitoring
400 army reserves
State of emergency called
1.2 mill. were issued with evacuation orders
57 emergency shelters set up e.g. Louisiana SuperDome
Levees built

17

Impacts of Hurricane Katrina

Levees breached in 53 different places
80% of city flooded
3m deep flooding
1,836 deaths
10,000 homeless
Food & clean water shortages

18

Failures of Hurricane Katrina

Levees not high or strong enough for category 5
Not enough transport to evacuate all

19

Cyclone Nargis - Myanmar 208

SE asia
Population - 55 mill.
LEDC
GDP per capita - £1900
1/1000 have internet
32/50 poorest countries

20

Causes of Cyclone Nargis - Myanmar 2008

Mangrove forests cut down for farming and tourism
Low lying land
Shallow continental shelf
No defences, no prediction, no evacuation
(Government refused help from foreign countries)

21

Impacts of Cyclone Nargis - Myanmar 2008

1.5 mill. severly effected
over 15,000 deaths
95% buildings destroyed
Millions left homeless
Sewage systems damaged - disease
Crops destroyed - hunger, loss of income
Electricity cut off
Roads swept away
Mosquitos - disease

22

Why the responses were so bad in Myanmar 2008

Poor responses - LEDC
No evacuation
Military government didn't allow help in from abroad

23

Benefits of volcanic eruptions

Fertile soil
Minerals
Sulphur Mining
Dramatic scenery attracts tourists
Generates geothermal energy

24

Ways earthquakes are measured

Richter scale - measures magnitude of an earthquake (strength of shaking)
Mercalli scale - measures the damage caused by an earthquake

25

Different types of tropical storms

Hurricanes
Cyclones
Typhoons

26

Tropical storms

Intense, low pressure systems (depressions)

27

Factors needed for tropical storms to form

Ocean water at least 27oC
Water at least 60m deep
Between the tropics of cancer and Capricorn
Low air pressure

28

Names of plates

Eurasian
Indo-Australia
Nazca
Pacific
Antarctic
North America
South America

29

Advantages of living in the tropics

Climate for growing crops
Fishing
Natural area
Tourist industry
Exotic fruit & fish