Natural hazards

Natural hazards

Extreme natural events caused by natural processes that threaten or have the potential to cause damage, harm or destruction to property or human life

Would natural hazards still occur without humans?

Yes as they are caused by natural processes

Is a natural hazard still considered a natural hazard if it occurs nowhere near any humans or property?

No

Types of natural hazards (4)

• Tectonic hazard

• Atmospheric hazard

• Biological hazard

• Geomorphological hazard

Example of tectonic hazards

• Earthquakes

• Volcanic eruptions

Example of atmospheric hazards

Tropical storm

Example of biological hazards

• Forestfires

• Wildfires

Example of geomorphogical hazards

• Landslides

• Flooding

Natural disaster

When the damage or destruction actually takes place as a result of the natural hazard

Hazard risk

Probability or chance of a natural hazard occurring

Factors affecting hazard risk (5)

• Population density

• Wealth

• Urbanisation

• Deforestation

• Global warming/climate change

How does population density affect hazard risk?

P - Population density has increased meaning more people live closer together

E - In these areas, people will struggle to find safety and evacuate

How does urbanisation affect hazard risk?

P - Urbanisation is people moving from the countryside to rural areas

E1 - If people live closely in small areas, they will struggle to find safety/evacuate and will continue to live in areas thought to be risky

E2 - More buildings built means more impermeable surfaces so surface run off may occur

How does global warming affect hazard risk?

P - Global warming is a type of climate change where the earth getting warmer

E - Th probability of hazards like tropical storms increases in intensity meaning more deaths/injuries

How does deforestation affect hazard risk?

P - Deforestation is the cutting down of trees

E - Less trees means more surface run off so the likelihood of flooding increases

How does poverty affect hazard risk?

P - Poorer people can’t afford MPPP strategies, technology not as advanced, protocols not in place

E - Less prepared for hazards so more likely to die/get injured

Name the 4 layers of the earth

• Crust

• Mantle

• Outer core

• Inner core

Crust

The surface of the earth that we stand on on

Name the 2 types of plate

Oceanic + Continental

Which plate is denser: oceanic or continental?

Oceanic

Which plate is heavier: oceanic or continental?

Oceanic

Which plate is lighter: oceanic or continental?

Continental

What is the thinnest layer of the earth?

Crust

What is the thickest layer of the earth?

Mantle

Which layers of the Earth are liquid?

Outer core

Which layers of the earth are solid?

Crust, Mantle and Inner core

What temperature can the inner core reach?

6000°C

Lithosphere

Crust + upper mantle

What is the lithosphere broken up into?

Several major fragments called tectonic plates

How many minor and major plates are there?

7 minor + 8 major

Plate boundary

Where 2 plates meet along the edges

Name the 3 plate boundaries

Destructive, constructive and transform

What is another name for a transform plate?

Conservative

Direction of plates at transform plate margin

Side by side

Direction of plates at constructive plate margin

Away

Direction of plates at destructive plate margin

Towards

What landforms/hazards occur at constructive plates? (4)

• Volcanic eruptions

• Earthquakes

• Ridge Push

• Shield Volcanoes

What landforms/hazards occur at transform plates?

Earthquakes

What landforms/hazards occur at destructive plates? (5)

• Volcanic eruptions

• Earthquakes

• Slab pull

• Stratovolcano

• Fold mountain

At what plates do earthquakes occur?

Transform + Constructive + Destructive

At what plates do volcanoes occur?

Constructive + Destructive

At what plate does a fold mountain form?

Destructive

At what plate does a shield volcano form?

Constructive

At what plate does a stratovolcano form?

Destructive

What type of volcano forms at constructive plate margins?

Shield volcano

What type of volcano forms at destructive plate margins?

Stratovolcano

How do earthquakes form at constructive plates?

• Plates are jagged/not smooth/rough base

• Plates move move apart and drag along the mantle

• Friction builds between mantle and plates

• Plates jolt/get stuck

• Pressure builds

• Seismic waves released from focus

• Small earthquakes

How do volcanic eruptions occur at constructive plates?

• Plates move apart

• Magma explodes through the gap between plates

• Becomes lava

• Volcanic eruption

• Cools for new rock

• Shield volcanoes form

How do earthquakes form at destructive plates?

• Plates are jagged/not smooth/rough base

• Plates move towards each other and collide

• Friction builds

• Plates jolt/get stuck

• Pressure builds

• Seismic waves released from focus

• Violent earthquakes

How do volcanic eruptions occur at destructive plates?

• Oceanic plates moves towards continental

• Oceanic plate subducts as its denser/heavier

• Plate sinks to mantle

• Melts to form magma

• Magma rises to the crust as it’s hot and less dense

• Pressure builds under the earths crust

• Magma escapes through the rock

• Volcanic eruption

• Stratovolcanoes form

How do earthquakes form at transform plates?

• Plates are jagged/not smooth/rough base

• Plates move alongside each other

• Friction builds between plates

• Plates jolt/get stuck

• Pressure builds

• Seismic waves released from focus

• Violent earthquakes

Why can volcanoes not occur at transform plates?

No space for magma to rise

What is a volcano with steep sides called?

Stratovolcano

Where do stratovolcanoes form?

Destructive plate margins

Where do shield volcanoes form?

Constructive plate margins

Where and how do fold mountains form?

At destructive plate margins, 2 continental plates meet

What scale do we use to measure earthquakes?

Richter Scale

Richter Scale

A scale to measure the magnitude of an Earthquake - 1 to 10

Focus

Where the pressure is released in the crust of the earth

Epicentre

The points on the earth surface directly above the focus

Seismic waves

The energy released in an earthquake from the focus

Foreshock

Occurs before the main earthquake begins

Main shock

The main or largest earthquake

Aftershock

Occurs after the main earthquake has ended. (It’s not always smaller; could be the same size)

Does a shallow focus or deep focus cause more damage?

A shallow focus has larger impact as seismic wave energy is stronger

Why does magma rise?

It’s hot and less dense

What is the old theory for tectonic plate movement?

Convection currents

Describe convection currents

• Inner core reaches 6000

• Heat heats up the magma

• Magma rises in the mantle because it’s less dense and hot

• When it gets near the crust, the heat splits and cause it becomes sudden that it sinks back to the core

• Reheated and process repeats

How did geographers disprove convection currents?

Using modern imagen techniques - identifying currents in the mantle through x rays

What is the new theory for tectonic plate movement?

Ridge push slab pull

What is the key force in ridge push slab pull?

Slab pull

What plate margin is the slab pull at?

Destructive

What plate margin is the ridge push at?

Constructive

3 reasons why the oceanic plate subducts under continental

• Heavier

• Denser

• Gravity speeds up process

Primary effects

Occurs immediately after the earthquake happens (direct effect) like buildings destroyed or injuries

Secondary effects

Occurs as a result of the primary effects (indirect effect) like homelessness or landslides

Immediate response

Response within days or weeks of the disaster like search and rescue

Long term response

Response within months or years of a disaster like rebuilding homes

What factors can influence the effects/responses of a natural hazard?

• LIC or HIC

• Rural or urban areas

• Magnitudes of earthquake

• Distance from epicentre

• Time of day

What is our LIC case study for earthquakes?

Gorkha, Nepal

What is our HIC case study for earthquakes?

L’Aquila, Italy

When was the Nepal earthquake?

2015

When was the Italy earthquake?

2009

What was the magnitude of the Nepal earthquake?

7.8 magnitude

What was the magnitude of the Italy earthquake?

6.3 magnitude

Nepal earthquake: Primary effects

• 8,841 killed

• 16,800 injured

• 600,000 buildings collapsed

• 7000 schools destroyed

• 26 hospitals destroyed

• Dharahara tower destroyed

Nepal earthquake: Secondary effects

• 1 million homeless

• Landslides/avalanches on Mt. Everest killed 19

• Rice seed ruined before monsoon season - food shortage, farming loss

• Tourism declined - jobs, money

Italy earthquake: Primary effects

• 308 killed

• 1,500 injured

• 10-1500 buildings collapsed

• San salvatore hospital collapsed

Italy earthquake: Secondary effects

• 67,500 homeless

• Aftershocks trigger landslides

• Mudflow caused by burst water pipe in town of Paganio

Nepal earthquake: Immediate responses

• 500,000 tents provided

• Free telephone calls

• UN set up field hospitals

• Facebook launched a safety feature for users to indicate if they’re safe

Nepal earthquake: Long term responses

• Farmers taught how to repair their equipment

• Stricter building controls enforced

• Lakes and river valleys cleared of landslide material - avoid flooding

Italy earthquake: Immediate responses

• 400,000 tents provided

• Italian Red Cross searching for survivors within an hour

• Water, hot meals, tents, blankets distributed by Italian Red Cross

• Mortages, bills, TV, Electricity and gas bills suspended

Italy earthquake: Long term responses

• Students in L’Aquila given free Transport, discounts on school equipment and no paying university fees for 3 years after earthquake

• Pay no tax in 2010

How many died in the Nepal earthquake?

8,841

How many died in the Italy earthquake?

308

How many buildings collapsed in Nepal earthquake?

600,000

How many buildings collapsed in Italy earthquake?

10,000-15,000

How many were injured in the Nepal earthquake?

16,800

How many schools collapsed in Nepal earthquake?

7000

How many hospitals collapsed in Nepal earthquake?

26