The Challenge Of Natural Hazards - Tectonic Flashcards
What is a natural hazard?
A natural event that threatens people or has the potential to cause damage, destruction and death
Examples of a natural hazard
Earthquake
Volcano
Tropical storm
What factors affect the impact of a natural hazard?
Population - distribution and density
Frequency
Location - rock type, land relief
Magnitude
Level of development & wealth
What are the 3 Ps?
Prediction
Preparation
Prevention
What layers of the earth?
Inner core
Outer Core
Mantle
Crust
What are convection currents?
Occurs in the mantle
Magma rises from heat and then sinks as it cools down
What do convection currents do?
Build pressure
Carry plates with them
What are the two types of crust?
Oceanic
Continental
Oceanic crust
Newer
Thinner
Denser - sinks
Continental crust
Older
Very thick
Not dense - cannot sink
What is slab pull?
When denser plates sink into the mantle - due to gravity
It pulls the rest of the plate along behind it
What is ridge push
Magma rises and the plates move apart
Magma cools - new material forms = more dense
Slides down away from ridge = tectonic plates move away from each other
What is continental drift?
Theory discovered by Alfred Wegnar
All continents used to be combined - called Pangea
What is evidence for continental drift
Continents fit like puzzle pieces
Correlation of fossils
Mountainous areas match neighbouring countries
What is a destructive plate margin
Two plates collide with each other - due to convection currents
Oceanic crust is more dense - it sinks into mantle
What natural hazards occur along a destructive plate margin?
Earthquake - friction between to plates causes earthquakes
Volcano - friction and heat from mantle melts rock, hot liquid rises and volcano erupts
What is a constructive plate margin?
Two plates move apart
A new crust is formed - mid ocean ridge
What natural hazards occur along a constructive plate margin
Volcano
Magma rises up to form a volcano filling the gaps
Magma cools as plates are pulled apart - gap forms
What is a conservative plate margin?
Two continental plates move parallel to each other
Friction and pressure build up
Energy is released and the two plates move at different rates
What natural hazard occurs along a conservative plate margin
Earthquakes
Friction from plates sliding against each other
What are the two types of volcanoes?
Composite and Shield
Characteristics of a composite volcano
Sticky, viscous lava
Destructive plate margins
Explosive
Travels slowly
Steep sided volcano
Characteristics of a Shield volcano
Runny Lava
Constructive plate margin
Non-explosive
Travels quickly
Shallow sided volcano
What are the seven main volcanic hazards
Volcanic Gases
Landslides
Lahar
Lava flows
Pyroclastic flows
Tephra
Jokulhlaup
Volcano Case study
Eyjafjallajokull, Iceland
Location of Eyjafjallajokull
Eruption was 100km away from the capital city of Iceland
Magnitude of Eyjafjallajokull
140million3 of material was ejected in the first five days
First 24 hours - 3.1 magnitude
Date and Time of Eyjafjallajokull eruption
Began in March 2010 - wasn’t a threat
14th -18th April - most explosive phase and height of crisis
Causes of Eyjafjallajokull eruption
The volcano had been active since 1863
Constructive plate margin runs through Iceland
Slab pull + convection currents
Primary effect of Eyjafjallajokull
Huge ash cloud - main hazard
Ice caps melted
Thick clouds of ash were omitted
Ash travelled impacting neighbouring countries
Secondary effects of Eyjafjallajokull
Transport was cut off
Air was polluted - injuring and disturbing
Jobs cut off meaning expenses stacked up - UK lost £102 million in 6 days
Immediate responses to Eyjafjallajokull
Airlines closed - ash damaged plane systems
Computers used to monitor the clouds movement
Long term responses to Eyjafjallajokull
Food had to be imported and without transport it was difficult
People began to question whether the strict guidelines were necessary
What is an earthquake
A sudden or violent movement within the Earth’s crust followed by a series of shocks
What is used to measure Earthquakes
Richter scale
1 = 10 times greater
What is a tectonic hazard
A natural hazard caused by the movement of tectonic plates
Epicentre
The point inside the crust where the pressure is released
Focus
The point of origin of an earthquake within the earths crust
Earthquake HIC case study
L’aquilla, Italy
Important facts about L’aquilla
L’aquilla is a city in central Italy
High Income country
Magnitude and time of L’aquilla earthquake
6.3 on Richter scale
6th April 2009 - 3.32am
Causes of L’aquilla earthquake
Destructive Plate margin
4.6 magnitude tremor shook the area
Primary effect of L’aquilla earthquake
10,000 buildings destroyed
Deaths were reported
People were looking for safety and shelter
Secondary effects of L’aquilla earthquake
Phone and power lines went down
Rescuers were sent to search the rubble;e
Landslides = rockfall
Bridges and roads closed
Immediate responses to L’aquilla earthquake
Declared a state of Emergency
People were hosted in tents and hostels
Free mobile calls
Rescue services were stretched to the breaking point
Long term responses to L’aquilla earthquake
Two field hospitals thrived
Open air medical help
11 million in cost damage
Earthquake LIC case study
Gorkha, Nepal
Important facts about Gorkha earthquake
City in Nepal
Low income country
Magnitude and date of Gorkha earthquake
7.8 magnitude on the Richter scale
25th April 2015
Causes of the Gorkha earthquake
Destructive plate margin
Build up of stress causing sudden thrusts
Tectonic forces built up movement along plates leading to earthquake
Primary effects of Gorkha earthquake
Earthquake triggered Avalanche on Mount Everest
Buildings were destroyed
Deaths reported
Belongings lost
Secondary effects of Gorkha earthquake
People had no house so had to sleep outside - exposed
Harvest was lost - income fluctuated - valuable food
Resources were running out
Tourism decreased - income decreased
Immediate responses to Gorkha earthquake
People were living in tents in fields
People pulled others out the rubble to help
International countries shared resources
Long term responses to Gorkha earthquake
Countries offered support
Task force for dealing with earthquakes cam to help
People were educated
5 billion cost damage
4 ways to manage tectonic hazards
Planning
Protection
Prediction
Monitoring
Why do people live in areas at risk from tectonic hazards
Richer soils - good for agriculture
Mining - energy and income
Can’t afford to move
Family and friends
Not understanding risk
Not high enough risk
