Plate Tectonics Flashcards
Where does a constructive plate margin occur?
- Where two plate margins are DIVERGING (moving apart)
How are volcanoes and earthquakes produced from constructive plates?
- The mantle is under pressure from the plates above it
- The release of pressure eventually causes the mantle to melt, producing magma. The magma is LESS DENSE than the plate, causing it to rise above it
- When the pressure becomes too much, the plates crack and buckle, causing a fault line and subsequently an earthquake
Where do constructive plates form?
Where plates are diverging away from each other
Where do destructive plates form?
- Occurs when two plates are converging towards each other
Where do conservative plates form?
- Occurs when two plates are moving past each other
How are earthquakes and volcanoes formed at constructive plate boundaries?
- Mantle under pressure from plates above and when they move, pressure is released
- Causes mantle to melt, producing magma and due to magma being less dense, it rises, forming a volcano
- The plate may eventually buckle and crack due to pressure, forming a fault line
How are ocean ridges created?
- Diverging plates underwater form a ridge
- Underwater volcanoes erupt along the ridges, building above sea level
How are rift valleys created?
- Plates diverge beneath land, rising magma causes continental crust to fracture
- Plates move and crust drops down forming a rift valley
What happens at oceanic - continental plates?
- Oceanic plate forced under the continental crust due to density
- Fold mountains form from sediments of continental crust, folding upwards
- Oceanic crust heats and melts into magma, rising to the surface, forming a volcano
- The plates get stuck and once they get dislodged, causes an earthquake
What happens on oceanic - oceanic plates?
- Similar to oceanic - continental
- Volcanic eruptions that take place underwater form island arcs
What happens at continental - continental plates?
- Neither subduct, forming fold mountains and earthquakes
Where do conservative plate boundaries form?
- Occurs when two plates are moving past each other
How do earthquakes occur at conservative plate boundaries?
- Plates get locked in place, building pressure
- Pressure gets released as the plates jerk past each other releasing the energy as an earthquake
What is a magma plume?
A vertical column of extra hot magma that rises from the mantle
How to magma plumes form chains of volcanoes?
- Magma plume reamins stationary, whilst crust moves above it
- Volcanic activity in the part of the crust that was above the plume decreases as it moves away due to continental drift
- A new volcano forms in the part over the plume
- This eventually forms a chain volcanoes, e.g. Hawaii
