Natural Hazards Flashcards
What are Natural Disasters?
Natural hazards become natural disasters when people’s lives and livelihoods are destroyed.
How can the effects of Natural Disasters be reduced?
By giving out accurate forecasts and warnings in advance.
What are the four layers of the Earth?
Inner core, outer core, mantle and crust.
What are tectonic plates?
These are plates made up of the Earth’s crust and the upper part of the mantle.
What is the theory of continental drift? What evidence is there to support it?
Continental drift is a theory proposed by Alfred Wegener. He believed that the Earth’s continents were once all joined together but over time, they gradually moved apart, forming the continents which we have today.
Evidence supporting it is the discovery of identical fossils in continents which are far apart from each other.
Why do tectonic plates move?
These move due to convection currents in the Earth’s mantle. These plates constantly move a few centimetres a year.
What are the two types of plates?
Oceanic and continental.
What are they three types of Plate boundaries?
- Destructive (sometimes called convergent on tensional)
- Constructive (sometimes called divergent plate or margin)
- Conservative (sometimes called transform plate margin)
What are Destructive plate boundaries?
This is when the two plates (oceanic and continental) move together, the oceanic plate subducts under the continental plate. Friction causes the oceanic plate to melt which could trigger an earthquake. Magma rises up through the cracks and erupts onto the surface.
What are constructive plate boundaries?
This occurs when plates move apart. Volcanoes are formed from this as the magma wells up to fill the gap. Eventually a new crust is formed.
What is the conservative plate boundary?
This is when plates are moving in different or the same directions but at different speeds. Friction is eventually overcome and this causes the plates to slip past each other in a sudden movement. The shockwaves cause an earthquake.
How are fold mountains created?
This is when neither plate goes over or under each other and are forced up. This forms fold mountains.
What are Natural Hazards?
Natural hazards are severe weather and climate events that occurs naturally in all parts of the world, however some regions are more vulnerable than others.
What are earthquakes?
An Earthquake is the shaking and vibration of the Earth’s crust due to the tectonic plates. Earthquakes occur when tension is built up between the plates when they get stuck. The tension is released from inside the crust, which tends to cause earthquakes.
What is the focus?
This is the point where seismic waves (how earthquakes release energy) are released. This is directly above the epicentre.
