Physical landscapes -
1. 3.1 - Tectonic processes and hazards
Crust = Low density rocks - Oceanic (basalt) 6km thick, Continental (granite) 70km thick
Mantle = upper is rigid, lower is molten
Core = Outer is molten, inner is solid metal at 5500°C
Ridge push =Diverging plate margins, upper mantle seeps out creating ridge, cools and slides
down ridge, repeats
Slab pull = Subduction zones, cold and dense plate sinks into mantle
Sea floor spreading = convection currents push plates apart, creating new crust
Continental drift = Ocean floor spreads so continents pushed apart
Conservative margin = plates moving alongside each other
Converging margin = plates move into each other
Diverging margin = plates move apart from each other
Richter scale = measures earthquake energy
Mercalli scale = measures earthquake effects
Volcanic Explosivity Index = strength of volcanic eruption
1.3.2 - Volcanoes, processes, hazards and their impacts
Mafic magma = basaltic, law viscosity, constructive boundaries and hotspots
Felsic magma = acidic, high viscosity
Effusive eruption = mafic magma, shield volcanoes
Explosive eruption = felsic magma, Strato and cinder and dome volcanoes
Stratovolcanoes = alternate layers of magma and pyroclastics, often dormant
Cinder volcanoes = small volume, small rock fragments piled up
Dome volcanoes = steep sides as lava cools quick and is very viscous
Shield volcanoes = gentle slopes, few pyroclastic materials
Primary hazards:
● Pyroclastic flows = high density mix of hot rock fragments and gases between 200°C
and 700°C
● Lava flows = streams of molten rock
● Ash fall = tiny, jagged pieces of rock and glass that are airborne
● Toxic gas =released from lava as it rises, denser than air so flow down mountainside and
gather in depressions
1. 3.1 - Tectonic processes and hazards
Crust = Low density rocks - Oceanic (basalt) 6km thick, Continental (granite) 70km thick
Mantle = upper is rigid, lower is molten
Core = Outer is molten, inner is solid metal at 5500°C
Ridge push =Diverging plate margins, upper mantle seeps out creating ridge, cools and slides
down ridge, repeats
Slab pull = Subduction zones, cold and dense plate sinks into mantle
Sea floor spreading = convection currents push plates apart, creating new crust
Continental drift = Ocean floor spreads so continents pushed apart
Conservative margin = plates moving alongside each other
Converging margin = plates move into each other
Diverging margin = plates move apart from each other
Richter scale = measures earthquake energy
Mercalli scale = measures earthquake effects
Volcanic Explosivity Index = strength of volcanic eruption
1.3.2 - Volcanoes, processes, hazards and their impacts
Mafic magma = basaltic, law viscosity, constructive boundaries and hotspots
Felsic magma = acidic, high viscosity
Effusive eruption = mafic magma, shield volcanoes
Explosive eruption = felsic magma, Strato and cinder and dome volcanoes
Stratovolcanoes = alternate layers of magma and pyroclastics, often dormant
Cinder volcanoes = small volume, small rock fragments piled up
Dome volcanoes = steep sides as lava cools quick and is very viscous
Shield volcanoes = gentle slopes, few pyroclastic materials
Primary hazards:
● Pyroclastic flows = high density mix of hot rock fragments and gases between 200°C
and 700°C
● Lava flows = streams of molten rock
● Ash fall = tiny, jagged pieces of rock and glass that are airborne
● Toxic gas =released from lava as it rises, denser than air so flow down mountainside and
gather in depressions
