Research - Plate Tectonic Flashcards
A model that shows that a natural disaster only occurs if a vulnerable population is exposed to a hazard
Degg’s Model
A natural event that has the potential to harm eg. Typhoon or volcano
Hazard
A natural hazard that affects human life or the economy eg. Typhoon Haiyan
Disaster
A theory proposed by Alfred Wegener in 1912, stating that the continents drifted apart over 250 million years from Pangea
Continental Drift Theory
Branch of geophysics concerned with the magnetism in rocks. As magma solidifies, the iron minerals align themselves with the magnetic North pole (magnetism flips every 200,000yrs)
Paleomagnetism
The process where the Earths Core is slowly broken down, driving convection currents causing tectonic plate movement
Decaying core
The solid, outer layer of the Earth. Consists of the crust and brittle upper solid portion of the mantle
Lithosphere
The zone of the Earth’s mantle much hotter and more liquid than the lithosphere
Asthenosphere
Rock that’s formed through the cooling and solidification of magma or lava. At constructive, basalt and at destructive, andesitic/rhyolitic
Igneous rock
Lower layer of Earth’s crust, namely rocks rich in silica and magnesium as basalt
SIMA
Upper layer of Earth’s crust, namely rocks rich in aluminium silicate minerals as granite
SIAL
fragmental material produced by a volcanic eruption
Tephra
An underwater deep-ocean rift valley at 3,000-6,000m. Found at oceanic constructive plate boundaries
Abyssal plain
A type of plate bouder where plates slide past one another without production or destruction of crust
Transform fault
Subsistence sections of crust between fault lines formed at a continental constructive plate boundary
Rift valley
As a tectonic plate moves further from an oceanic ridge, it cools and becomes denser causing it to sink beneath a continental crust
Slab pull
Boundary between subduction plate and overlying crystal rocks ….
Wadati Benioff Zones
Occurs at collision plate boundaries where magma plumes are trapped beneath the surface
Relic subduction
The convergence of two plates of continental crust
Collision Margin
A system of parallel mountain ranges eg. Andes
Cordillera
A curved chain of volcanic islands (due to Earth’s curvature) located at a tectonic plate margin usually with a deep ocean trench
Island Arc
An stationary plume where molten magma breaks through the Earth’s crust and as the plate moves, the basic shield volcano becomes inactive eg.Hawaii
Hotspot
An underwater mountain which was previously a hotspot volcano and due to erosion and plate movement has a flat top underwater.
Guyots
A line of islands formed by tectonic plate movement over a hotspot, forming volcanoes and then inactive mountains eg. Hawaiian islands
Linear island chain
AKA an archipelago
Clustered island chain
The immediate hazards of an eruption coming directly from it eg. Pyroclastic flows
Primary hazard
Indirect hazards caused by primary volcanic hazards which occur on a longer timescale eg. Lahars
Secondary hazards
Volcanic hazards that result from secondary hazards and have a very long term human impact after the eruption
Tertiary hazards
A mixture of water, rock, ash and sand from a volcano due to heavy rainfall or heat from a volcanic vent melting ice
Lahar
High speed avalanches of hot ash, rock fragments and gas, 800°c
Pyroclastic flows
Volcanic Explosivitiy Index. Measures a out of tephra created on a log scale
VEI
Highly viscous lava (high in silica ~70%) forms granite, at destructive plate boundaries, forms composite cone volcanos and cooler than basic (~800°c)causing violent eruptions due to trapped air
Acidic lava
Less viscous lava due to lower silica content (~50%) forms basalt found at constructive plate boundaries and hotspots, higher temps (~1200°c), forms shield volcanos with smaller more frequent eruptions
Basic lava
Heat from cooling magma can cause hydrothermal change of the rocks, turning into clay, weakening it and increase risk of slope failure
Landslides
When masses of water/ ice are suddenly released from a glacier
Jökuhlaup
Point inside crust to where the pressure is released, causing an earthquake
Focus
Point at the surface of the crust directly above the focus
Epicentre
Known as moment magnitude scale, measures seismic movement + strength (seismograph) and rigidity of rock + amount of slip
Richter scale
Measure of earthquake scale from 1-12 based upon total destruction of all buildings (subjective)
Mercalli scale
Earthquakes caused by tectonic plate movement plate boundaries eg. Ridge, transform, rift, Wadatti Benioff zones
Tectonic earthquakes
Earthquakes that occur at interplate hotspots, usually with a shallower focus and less scale
Magmatic earthquake
A zone of seismic activity on the two slabs just above the subduction zone
Wadatti Benioff zones
Earthquakes on one side of a volcano. Due to a bulge in the magma chamber
Earthquake swarm
Push waves that travel through the Earth, primary waves recorded
P waves
Shake waves, travels through Earth and are secondary waves recorded
S waves
Long waves that travel along the Earths surface, producing large movement and most destructive, last waves recorded
L waves
Theory that earthquake hazards increase with time due to increased pressure between plates
Seismic Gap theory
First phase of a tsunami where it’s created either by: earthquake-causing displacement, earthquake-caused landslide or volano
Génération phase
Second phase of tsunami where it’s travelling in the deep sea with a long wavelength and low crest
Propagation phase
Third phase of tsunamis where it hits the sea beds and slows due to friction
Shoaling phase
Final have of a tsunamis where it hits land and then the wave moves back into the sea
Inundation + Drawback phase
A scale for tsunamis (similar to mercalli scale)
Tsunami intensity scale
Where a tsunami curves around a coastline
Wave refraction
The sudden movement of plates due to built-up pressure creating large earthquakes (seismic gap theory)
Megathrust
A technological disaster caused by natural disaster eg. Fukushima
Natec
how quickly the peak of the hazard event occurs, how long it takes to travel from focus to disaster zone eg. Earthquakes
Speed of onset
The ability of people, organizations and systems, using available skills and resources, to manage, money, aid + protection
Capacity to cope
Measures the risk of a hazard (both physical and social): hazard (mag+frequency) x vulnerability/ capacity to cope
Risk equation
A factor of the risk equation that measures land degradation and land use as well as the population vulnerability
Vulnerability
Sensationlisation of a disaster by journalists
