Keywords - tectonics Flashcards
Ash
Very small solid particles ejected from a volcano during an eruption
Aseismic building design
A design for earthquake-resistant buildings which is developed to limit the potential damage to buildings to a tolerable level
Athenosphere
The upper layer of the Earth’s mantle, where convection occurs
Benioff zone
The linear zone where a descending oceanic plate is in contact with a continental plate as it is subducted. This is a zone. Of earthquake activity created by the two plates, which creates stresses and strains which are suddenly released.
Collision plate margin
Where two plates are colliding into each other, which create fold mountains - usually continental and continental
Convergent plate margin
Where the oceanic plate is subducted under a continental plate
Composite cone volcano
Also known as a cone volcano, it has steep sides and its eruptions are explosive. It erupts low silica lava which is thick and sticky meaning it cannot run very far creating the steep sides.
Conservative plate margin
Occurs where plates slide past each other in opposite directions or in the same direction but at different speeds. Friction is eventually overcome, and the plates slip past in a sudden movement. The shockwaves created produce an earthquake
Constructive plate margin
Two plates moving away from each other
Destructive plate margin
A destructive plate margin forms when an oceanic and continental plate moves towards each other. The heavier, denser oceanic plate subducts the continental plate. The oceanic plate melts and it sinks below the continental plate due to friction in the subduction zone and the heat of the mantle
Divergent plate margin
Two plates moving away from each other
Disaster
An event, such as an earthquake, that disrupts normal conditions to a point where a place or community cannot adjust and there is significant loss of life and injuries and financial cost.
Earthquake seismic waves
The shockwaves created by the release of the tension at a focal point
Epicentre
The point on the Earth’s surface directly above the hypocentre where the seismic energy is felt the most
Focal depth
The depth at which an earthquake starts. It is divided into shallow, intermediate and deep. Shallow earthquakes have the greatest impacts
Hazard
Something that has a negative impact on people in any way
Hazard management cycle
A sequence of actions and decisions related to a place or area being prepared for or responding to the threat of a natural hazard
Hazard profile
An analysis of different types of hazard or actual hazard events based on a range of criteria. This allows a useful comparison to be made
Hot spot volcano
An intra-plate location, oceanic or continental, where magma from the mantle has broken through a weak point in the crust
Hydro-meteorological hazards
Hazards associated with flowing water or the weather. These may combine with tectonic hazards, for example lahars
Hypocentre
The point inside the crust where the pressure and seismic energy is released
Intensity
The amount of damage creates by a tectonic event or other hazard
intraplate
Tectonic activity that is found away from the plate boundaries and closer to the middle of a tectonic plate
jokulhlaups
A tectonic hazard common in Iceland, where volcanic activity underneath ice caps creates large volumes of meltwater which suddenly burst out as floodwaters under the ice, when the water pressure reaches a certain level.
Lahar
A mixture of meltwater from snow and ice on top of an active volcano and tephra from eruptions that travels very quickly down existing river valleys.
Landslide
Are large masses of wet or dry rock and soil that fall, slide or flow very rapidly under the force of gravity. Landslides are common on tall, steep and weak volcanic ones.
Lava flow
A mass of flowing or solidified lava
Liquefaction
Occurs when vibrations or water pressure within a mass of soil cause the soil particles to lose contact
Lithosphere
The rigid outer part of the Earth, consisting of the crust and upper
Magnitude
The amount of energy released by a tectonic event
Mantle convection
The movement of mantle material in cells when heated by radiation from the Earth’s core
Mantle plumes
They are the hotter areas of the mantle that move upwards underneath the crust and push it up. They can cause weak points in the crust which can become hotspots.
Mercalli scale
An earthquake intensity scale based on 12 levels of damage to areas
Moment magnitude scale
The most accurate earthquake scale, it measures the total energy released by an earthquake
Multiple hazard zones
A country or region that experiences several natural hazards, such as earthquakes, volcanoes, river floods
Natural hazards
A physical geographical event, tectonic, hydrological, or meteorological, which has a negative impact of people through causing injury or death
Paleomagnetism
When magmas and lavas solidify, the iron minerals in the rock align with the Earth’s magnetic field, permanently recording the direction.
Pyroclastic flow
A very fast-moving cloud of superheated gases and ash travelling at ground level
Sea floor spreading
The movement of the oceanic crust away from a constructive plate boundary
Slab pull
At a subduction zone the descending part of the oceanic tectonic plate pulls the rest of the plate with it.
Subduction
The process involving the descent of an oceanic plate into the upper mantle beneath a continental plate
Transform margin
Where two plates meet at a major fault in the Earth’s crust
Tsunami
A sequence of huge waves created by a large displacement of seawater, usually by an undersea earthquake.
Volcanic explosivity index
The scale used to measure the magnitude of a volcanic eruption
Water column displacement
The movement of a volume of seawater above the point at which the seabed was moved up or down by an earthquake event such as thrust
Crustal fracturing
when two tectonic plates moving into or next to each other creates a locked fault. Produces lots of strain which builds up elastic energy. The pressure and energy exceeds the strength of the plates which results in the energy being released.
Love waves
they come from the epicentre - only travel through crust, faster surface wave. They move from side to side as it moves forward. Causes the most damage due to longer wavelength and focus of energy at surface
P- waves
Caused by compression pushing and pulling in the direction of travel. They are the fastest and arrive first
S-waves
slower, only move through solid rock, up and down movement, only through crust
