Tectonic Keywords Flashcards
Ash falls
Small particles of rock and volcanic glass that land after a volcanic eruption has blasted them into the air
Asthenosphere
The part of the mantle, below the lithosphere, where the rock is semi molten
Benioff zone
The area where friction is created between colliding tectonic plates, resulting in intermediate and deep earthquakes
Body waves
The group name for primary and secondary seismic waves, because they travel through the earths body
Collision margin
Where two continental plates meet and the sediments between them are crumpled and forced up to form high fold mountains
Conservative plate margin
Where two plates slide past each other also known as a transform margin
Constructive margin
Where two plates move apart, also known as a divergent boundary
Continental crust
Older, thicker layer of crust, which makes up the earths landmasses. It is less dense than oceanic crust
Convection currents
Hot, liquid magma currents moving in the asthenosphere
Convergent boundary
Where two plates move towards each other and collide, also know as a destructive margin
Crustal fracturing
When energy released during an earthquake causes the earths crust to crack
Deep ocean trench
A deep ditch in the ocean, marking the place where an oceanic plate starts to sink beneath a continental plate
Destructive margin
Where two plates move towards each other and collide, also known as a convergent boundary
Divergent boundary
Where two plates move apart, also known as a constructive margin
Epicentre
The point on the earths surface directly above the focus
Focus
The point inside the earths crust from which the pressure is released when an earthquake occurs
Fold mountains
Chains of mountains, formed when two plates collide and the continental plate is folded and slowly pushed up
Gas eruptions
When volcanic gases (water vapour, carbon dioxide and sulphur dioxide) that were dissolved in the magma are released into the atmosphere during an eruption
Hazard adaptation
Strategies designed to reduce the impacts of hazard events
Hazard mitigation
Strategies meant to avoid, delay or prevent hazard events
Hazard management cycle
a theoretical model of hazard management as a continuous 4-stage cycle involving mitigation, preparation, response and recovery
Hot spot
an area where radioactive decay within the Earth’s core is concentrated, generating very hot temperatures and heating the lower mantle. This creates localised thermal currents where magma plumes rise
hydrometeorological hazards
natural hazards caused by climate processes (including droughts, floods, hurricanes and storms)
Intra plate earthquakes
Earthquakes which occur far from the plate margins
Island arcs
curved lines of islands, formed when underwater volcanoes grow and rise above sea level to form separate island volcanoes
jökulhlaups
A heavy and sudden flood caused when the heat of a volcanic eruption melts the snow and ice in a glacier
L waves (surface Love waves)
Seismic waves which travel on the surface and are the slowest waves but cause the most damage
Lahars
Masses of rock, mud and water that travels quickly down the sides of a volcano
Land use zoning
A process by which local government regulates how land in a community may be used
Landslides
when blocks of rock moves very rapidly downhill, caused when the ground shaking during an earthquake places stress on the slopes
Lava flows
streams of lava that have erupted from a volcano onto the Earth’s surface
Liquefaction
when the violent shaking during an earthquake causes surface rocks to lose strength and become more liquid than solid
Lithosphere
the solid layer, made from the crust and upper mantle, from which tectonic plates are formed
Magma plume
a rising column of hot rock created by hot spots heating the lower mantle, creating localised thermal currents
Mid ocean ridges
underwater mountain ranges, formed when hot magma is forced up from the asthenosphere and hardens, creating new oceanic crust
Modified Mercalli Intensity Scale
takes observations from people who experienced the earthquake and rates them on a scale from I (hardly noticed) to XII (catastrophic)
Moment magnitude scale
measures the total energy released by an earthquake at the moment it occurs
Multiple hazard zone
an area that is at risk from multiple natural hazards such as hurricanes and earthquakes
Natural disaster
a major natural hazard that causes significant social, environmental and economic damage
Natural hazard
a naturally occurring process or event that has the potential to affect people
Non governmental organisation
a non-profit organisation created by private organisations or people with no participation or representation by any government
Oceanic crust
a thin, dense layer of crust, which lines the ocean floors
P waves (Primary or pressure waves)
the fastest seismic waves and the ones which reach the surface first. They are high-frequency and pushing like balls in a line. They travel through both the mantle and core
palaeomagnetism
the study of past changes in the Earth’s magnetic field
Pressure and release model
a tool used to work out how vulnerable a country is to hazards
Pyroclastic flows
a mixture of dense hot rock, lava, ash and gases ejected from a volcano, which move very quickly across the Earth’s surface
Rift valleys
steep-sided valleys, formed at divergent boundaries when the crust stretches and the land between parallel faults collapses
S waves (Secondary or shear waves)
seismic waves which are slower than P waves and only travel through solids, with a sideways motion. They do more damage than P waves
Sea floor spreading
when new oceanic crust – formed when hot magma is forced up from the asthenosphere and hardens – pushes the tectonic plates apart
Slab pull
when newly formed oceanic crust sinks into the mantle, pulling the rest of the plate further down with it
Subduction
when two plates move towards each other and one slides under the other into the mantle
Subduction zone
the area in the mantle where a tectonic plate melts
the Park model (hazard- response curve)
shows how a country or region might respond after a hazard event
Transform fault
A fault created on a large scale when two plates slide past each other
Transform margin
Where two plates slide past each other, also known as a conservative boundary
Tsunami
A series of larger than normal waves which are usually caused by volcanic eruptions or underwater earthquakes
Urbanisation
The increasing proportion of people living in towns and cities as opposed to the countryside
Volcanic Explosivity Index (VEI)
A logarithmic scale between 0 and 8 which is used to describe and compare the size or magnitude of volcanic eruptions
Water column
Water that is displaced above the sea floor when an earthquake has caused the sea floor to uplift. This water column will form tsunami waves
