TECTONICS:EQ1 Flashcards
Earthquake
The shaking or vibration of the tectonic plates
Intra-plate earthquakes
Earthquakes that occur inside plates due to stresses in the crust
Constructive plate boundaries
plates move away from eachother at different speeds building pressure until plates crack. ,<>
At Destructive plate boundaries
also conergent movemnt . Subduction occurs here one plate is forced underneath the other gets srtuck due to friction . >_
Asthenosphere
The upper mantle layer of the earth . semi-molten
Lithosphere
The upper crust of the earth . thickness=100km
Wadati-benioff zone
a region of the subducting plate .affected by the pressure and friction mostly at destructive plate boundaries
Slab pull
The force contributing to the movemrnt of tectonic plates
Paleomagnetism
alternating change in poles of the earth every 400,000 years
Pyroclastic flows
A mixture of gases and rock fragments released at high temperatures travelling at rapid speeds
Oceanic crust
Crust usually thinner forms the seafloor average 10km thick
Continental crust
Crust that forms the continets of the lithosphere
Lahars
A flow of mud and debris
Jokulhaup
a sudden glacial flood caused by a galcier on top of the melting volcano
Convection currents
Circulation of magma within the asthenosphere . The magmanis heated by radioactive processes
Tsunami
Generated when a submarine earthquake displaces the sea bed as a result of movement along a fault line. secondary impact of earthquakes
Natural hazard
has the ability to affect populations, infrastructure . Can be either hydrometeorological or geophysical .
Evidence of plate tectonic theory
1.Sea floor spreading
2.climate
3.paleomagnetism
4.geology
focus
where the energy radiates from
epicentre
point direc tly above the focus on the earths surface
shallow focus earthquakes
where the focus is 0-70km under the earths surface
Deep focus earthquakes
where the focus is 70-700km under the earths surface . less damaging as shock waves travel further . caused by previously subducted plates
P-waves
primary waves , fastest wave causing the least damage
S-waves
Secondary waves (make ground shake violently)
L-waves
Large waves create significant damage in terms of crustal fracturing
Crustal fracturing
primary hazard of earthquakes earths crust physically splitting
Ash falls (Tephra)
secondary hazard of solid material of fine ash ejected into the atmosphere
Volcanic gases
gass that are released after a volcanic eruption. carbon dioxide , carbon monoxide , sulfur
Pyroclastic flows
dense hot ash rock and gas ejecting explosively from vlcanoes
Natural hazard
Geophysical event that has the ore total to threaten both life and property
Disaster
The realisation of a hazard when it causes a significant impact on a vulnerable population
Risk =
Hazard X Exposure Vulnerability divided by manageability
Resilience
The ability of a community to spring back after a natural hazard
Vulnerability
Measure of someone’s inability to recover from a disaster
Capacity to cope
Ability of people, organisations and systems using available skills to manage conditions
PAR model
Seeks to explain how the intersection of unsafe conditions and hazards create vulnerability
