Mini-Lesson: Natural Hazards

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Human impact

Clearing a wide area of trees

Creation of cities and towns

The overall increase in global temperatures

Extraction of resources from underground

Tsunamis

• A large ocean wave caused by an underwater disturbance such as volcanic eruptions, earthquakes, or landslides.
• As a tsunami moves towards the shore, it increases in height.

Test your survival knowledge!

Landslides

• Sudden movements of rocks or soil down a hill or mountainside

• Primarily caused by the force of gravity

• Types:

• rockfalls
• mudflows
• creeps
• avalanches

Tornadoes

• A tornado is a destructive weather event characterized by rotating winds.
• Tornadoes are typically measured using the Enhanced Fujita (EF) Scale.

Droughts

• Droughts are prolonged period of abnormally low rainfall, leading to a shortage of water.
• Droughts can affect many areas of life:
• Economic
• Agricultural
• Ecosystem
• Human health and famine

The table provides data on the earthquakes recorded for four different cities over a ten year period.

Hurricanes

• A hurricane is a tropical storm with powerful winds.
• The development of a hurricane is often divided into four stages:
• tropical disturbance
• tropical depression
• tropical storm
• hurricane

Thunderstorms

• Thunderstorms are characterized by lightning, thunder, and heavy rain.
• They can also produce strong winds and tornadoes.
• Three stages of formation:
• Cumulus
• Mature
• Dissipating

Earthquakes

We describe how strong it is by magnitude. Earthquake magnitude is a number that tells us how big or powerful an earthquake is, representing the total energy released

• Under 2.5: Usually not felt, but recorded by instruments.
• 2.5 - 5.4: Often felt, but only causes minor damage.
• 5.5 - 6.0: Slight damage to buildings.
• 6.1 - 6.9: A lot of damage in populated areas.
• 7.0 - 7.9: A "major" earthquake, causing serious damage.
• 8.0 and higher: A "great" earthquake, causing total destruction to buildings and severe damage over huge areas

• The sudden shaking of the ground caused by the movement of tectonic plates.
• Most likely to occur at plate boundaries where plates interact.

Volcanoes

• Volcanoes are mountains formed by lava and pyroclastic material
• Magma type determines eruption type:
• Felsic = violent and explosive
• Mafic = gentle and quiet