A-Level Geography – Tectonics
Exam Review 2023
(EQ1) What is the global distribution of earthquakes? - Answer-Most earthquakes =
near tectonic plate
... [Show More] boundaries - clusters of foreshocks, main quakes + aftershocks.
~70% earthquakes = 'Ring of Fire', Pacific Ocean. Most earthquakes --> destructive +
conservative plates.
(EQ1) What is the global distribution of volcanoes? - Answer-Most volcanoes = near a
tectonic plate boundary. North + South America --> active volcano zones. Some
volcanoes = hot spots - i.e. Hawaii
(EQ1) What is the global distribution of tsunamis? - Answer-1) 70% Pacific Ocean
2) 15% Mediterranean Sea
3) 9% Caribbean Sea and Atlantic Ocean
4) 6% Indian Ocean.
(EQ1) What are divergent plate boundaries? - Answer-Divergent = constructive.
Two oceanic plates move a part each other - forms new oceanic crust made of magma
rising from the asthenosphere
Low magnitude earthquakes (5-6) + low VEI volcanoes (1-3)
(EQ1) What are convergent plate boundaries? - Answer-Convergent = destructive.
Subduction of oceanic crust --> moving into the asthenosphere through slab pull.
Continental plate moves towards the oceanic crust = subduction of the oceanic plate
because it is denser and thinner.
High magnitude earthquakes (8-9) + moderate/high VEI volcanoes (5-6)
(EQ1) What are collision plate boundaries? - Answer-Same as convergent, but two
oceanic plates --> the thinnest = subducted.
Moderate magnitude earthquakes (6-8) and no volcanoes
(EQ1) What are transform plate boundaries? - Answer-Transform = conservative.
Oceanic + continental plate slide past each other, w/o creating/destroying lithosphere.
Moderate magnitude earthquakes (6-8) + no volcanoes.
(EQ1) How are intraplate earthquakes triggered? - Answer-1) Ancient fault lines =
triggered through movement on mantle --> old hard rock to fracture = earthquake.
2) Collisions of established plate boundaries = fractures in middle of plate = earthquake.
(EQ1) How are intraplate volcanoes formed? - Answer-Mantle plumes - upwelling of
magma from the core = plume partially melting when reaching shallow depths =
hotspots --> heat can rise and w/the low pressure at base of lithosphere = melts the
rock + allows for magma to form volcanoes.
Meteorite impacts could also create symmetrical volcanoes.
Continues... [Show Less]