Geography P1 Key terms

• Accretion Wedge


  The accumulation of material at the point of subduction
• Assamic Buildings


  • Buildings designed to withstand or minimise destruction during an earthquake
• Asthenosphere


  The upper mantle layer of the Earth, approximately 2000km wide
• Ash


  Fine particles and dust ejected during an eruption, which can remain airborne in clouds or accumulate on the ground
• Continental Crust


  Crust that forms the continents of the lithosphere, on average 35km thick
• Continental Drift


  The movement of tectonic plates, due to varying weights of crust, originally thought to be caused by convection currents but now thought to be primarily driven by slab pull
• Controlled Burning


  Intentionally burning vegetation with the aim of reducing fuel available for a wildfire and disrupting the fire's path
• Convection Currents


  The circulation of magmas heated by radioactive processes in the asthenosphere, causing magma to rise to the surface and circulate
• Coriolis Effect


  The Earth's spinning motion affecting the path of moving objects and winds, depending on a location's latitude
• Crown Fires


  • Wildfires that burn the entirety of a tree crown, the most destructive and dangerous type of wildfire
• Degg's Model


  A model showing that a hazard becomes a disaster if it affects a vulnerable population
• Epicentre


  The point on the surface directly above the earthquake's origin
• Fatalism


  The belief that natural disasters are uncontrollable, so any losses should be accepted and not prevented
• Fire Breaks


  The clearing of trees and vegetation to create gaps to disrupt a wildfire's path
• Focus


  The place in the crust where the pressure-released seismic energy is released
• Ground Fires


  • Wildfires that burn through the peat and vegetation beneath the surface, making them slow but once established, difficult to extinguish
• Hazard Management Cycle


  The sequence of governance of a natural hazard: preparedness, response, recovery, and mitigation
• Hot Spot


  Volcanoes found away from the plate boundaries, caused by a magma plume closer to the surface
• Jökulhlaup


  A sudden glacial flood caused by a volcanic eruption melting the overlying ice, resulting in a flow of mud and debris
• Lithosphere


  The upper crust of the Earth, with an average thickness of 100km
• Love Waves


  A surface earthquake wave with horizontal displacement
• Mid-Ocean Ridge


  Diverging oceanic plates at a constructive plate boundary create a ridge, with new oceanic crust forming in the valley
• Moment Magnitude Scale


  A measure of an earthquake's energy released, considered the most accurate
• Oceanic Crust


  Crust usually thinner than continental crust, that forms the sea floor, with an average thickness of 7km
• Paleomagnetism


  The alternating polarisation of new land created, as magma cools and the magnetic elements within align with the Earth's magnetic field, which can alternate over thousands of years
• Park's Model


  A model describing the decline and recovery of a country over time, following a natural disaster
• Partial Melting


  Elements within the lithosphere have different melting points, so rock is partially melted and partially solid
• Primary Waves


  An earthquake wave causing compressions within the body of rock
• Pyroclastic Flow


  A mixture of gases and rock fragments, at high temperatures traveling at rapid speeds
• Rayleigh Waves


  A surface earthquake wave causing both horizontal and vertical displacement
• Richter Scale


  A logarithmic measure of an earthquake's intensity
• Secondary Waves


  An earthquake wave causing vertical displacement within the body of rock
• Seismic Waves


  The energy released during an earthquake, in the form of Primary, Secondary, Love and Rayleigh Waves
• Slab Pull


  The force contributing to the movement of tectonic plates, due to the weight of the plate
• Subduction


  Oceanic plate is forced below continental plate, due to the oceanic plate being more dense than the continental plate
• Surface Fires


  Wildfires that only burn the leaf litter, and so are the easiest kind to extinguish
• Tropical Storm


  A low pressure system of spiralling winds (due to the Coriolis Effect). Also called hurricanes, cyclones, and typhoons depending on the location they occur in
• Tsunami


  Initial vertical water displacement (often from a submarine earthquake) creates waves with large destructive power
• Volcanic Explosivity Index (VEI)


  A measure of the magnitude of a volcano's eruptions
• Volcanic Island Arc


  A series of volcanoes (often in the shape of an arc) that are formed consecutively, as a tectonic plate moves across a magma plume