Natural Hazards Flashcards
What are the four layers of the Earth?
Inner core, outer core, mantle and crust.
Name the two type of plates?
Oceanic and continental.
What are tectonic plates?
Two sub-layers of the Earths crust.
How do tectonic plates move?
They move because heat from the core causes convection currents in the mantle. These currents slowly move the crust around. In some places the crust is destroyed and in other places a new crust is formed.
What tectonic plate do we live on?
The Eurasion plate.
What is a continental drift?
When plate tectonics move. Earthquakes and volcanos often occur around there edges.
What is the theory of continental drift?
The theory of continental drift is that the Earth’s continents were once joined together, but gradually moved apart over millions of years. It offered an explanation of the existence of similar fossils and rocks on continents that are far apart from each other.
What does down warping mean?
When plates are being pushed down, forcing them to change shape.
What is subduction?
A process where the denser plate is pushed or dragged beneath the less denser plate.
What are fold mountains?
A feature such as the Himalayas that is created by two continental crusts meeting.
What are plate boundaries?
Places were two or more plates meet.
What are the three types of plate boundaries?
Constructive, conservative and destructive.
What is the constructive plate boundary (divergent plate margin)?
A plate boundary that occurs when plates move apart. This is how volcanoes are formed as magma wells up to fill the gap, and eventually new crust is formed.
What is a destructive plate boundary (convergent)?
A plate boundary that occurs when the oceanic and continental plates move together. The oceanic plate is forced under the lighter continental plate. Friction causes melting of the oceanic plate and may trigger earthquakes. Magma rises up through cracks and erupts onto the surface.
What is a conservative plate boundary (transform plate margin)?
A plate boundary that occurs where plates slide past each other in opposite directions, or in the same direction but at different speeds. Friction is eventually overcome and the plates slip past in a sudden movement. The shockwaves created produce an earthquake.
How do volcanos form?
Volcanoes form when magma reaches the Earth’s surface, causing eruptions of lava and ash. They occur at destructive and constructive plate boundaries.
What is a convection current?
Movement within the mantle caused by the heat of the core.
What is a natural hazard?
Severe and extreme weather and climate events that occur naturally in all parts of the world, although some regions are more vulnerable to certain hazards than others.
What is the focus?
This is the point where seismic waves (how earthquakes release energy) are released. This is directly above the epicentre.
What is the epicentre?
The epicentre is the point below the focus. It is the point where the earthquake exactly happens.
What is the ring of fire?
The ring is an area around the edges of the Pacific Ocean that has high volcanic an earthquake activity. It is a result of the plate tectonics.
What is an earthquake?
An earthquake is a sudden shockwave caused by rocks being under stress from the movements of plates at plate boundaries. Eventually the stress in the rock builds up enough to deform and reach breaking point. At that point, the stored up energy is released in the form of shockwaves. Large earthquakes are usually connected with plate boundaries.
