A-Level Geography – Tectonics Exam Review 2023

A-Level Geography – Tectonics Exam Review 2023 (EQ1) What is the global distribution of earthquakes? - Answer-Most earthquakes = near tectonic plate 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...