Natural Hazards Flashcards
3 different types of natural hazards
Atmospheric/climatic
- storms
- flooding
- tornadoes
- droughts
Hydrological
- floods
- tsunamis
Tectonic
- earthquakes
- volcanoes
4 factors that increase the risk of natural hazards
Climate change
- ⬆️ temp
- ⬆️ pressure
- ⬆️ sea levels
Farming
- flat land = floods
- methane = climate change
Poverty
- 🔻money for preparation/protection
- 🔻lack of education
- 🔻emergency services
Urbanisation
- ⬆️ impermeable surfaces
- ⬆️ lives at risk
Which type of tectonic plate is denser?
Oceanic
Theory of continental drift by Alfred Wegener
200m years ago continents were merged into a supercontinent called Pangea
Proof:
- edges of continents match the shapes of others
- similar patterns of rocks and fossils where continents would’ve met
What are convection currents?
A movement within the Earth’s mantle caused by the heat of the core.
- hot magma rises (heated by earths core)
- cools when it reaches earth’s surface and sinks
- causes slab pull of the tectonic plates above meaning they sink and pull apart (follow the direction of the currents)
Constructive plate boundary
2 plates moving away from each other.
- causes magma to erupt between them
- creates a shield volcano
Destructive plate boundary
Oceanic crust is denser and sinks under the continental crust
- caused by convection currents, so the plates move towards each other
- then the oceanic crust subducts (creating a subduction zone)
Creates earthquakes
Leaves a composite volcano
- the sinking plate in the mantle melts to form magma
- the pressure of the magma builds up beneath the Earth’s surface
- magma escapes through weaknesses in rock through a composite volcano
(eruptions are often violent, with lots of steam, gas and ash)
What is the contrasting earthquake case study?
(flashcards in a separate deck)
Chile and Nepal
How to reduce the risk of tectonic hazards? (3 ways)
Prediction
- using seismometers to monitor tremors
- monitor gas emissions (⬆️ quantity signals start if eruption)
Preparation
- earthquakes drills
- emergency kits
- education
- structurally sound buildings
Protection
- steel frames which can sway
- rubber shock absorbers
- open areas for easy evacuation
Where are earthquakes found?
Along all types of plate margins
Where are volcanoes found
Only along constructive and destructive margins.
Most volcanic activity happens along the ‘ring of fire’ (a group of volcanoes located along the Pacific plate margin
Conservative plate boundary
2 continental plates slide past each other and cause an earthquake due to friction
Collision plate boundary
2 continental plates move towards each other and buckle up which creates fold mountains
Why do people live near volcanoes? (4)
Farming
- fertile soils from the ash & minerals
- eg. Mt Etna sicily
Heating
- geothermal energy for a low cost
- eg. Iceland
Mining
- lava from deep down contains minerals
- eg. Gold or silver
Tourism
- lots of jobs are created
- eg. Blue Lagoon
High pressure (weather)
Thing depressing! 😞
Cold, dense, sinking air
- causes anticyclones (high winds)
- dry air (no evaporation- cold🥶)
- settled weather
DRY AND CLEAR DAYS ☀️🥶
