Tectonic processes and Hazards Flashcards
what are the 3 types of earthquake wave?
- primary
- secondary
- love
describe the features of a primary wave?
- pushes through the crust, mantle and core
- fastest wave
- travels through solids and liquids
- only damaging in powerful EQ’s
describe the features of a secondary wave?
- shakes through the crust and mantle
- slower than p-waves
- travel through solids
- damaging
describe the features of a love wave?
- vibrates side to side
- slowest wave
- most damaging
- large + focuse all energy on earths surface
what are the 2 earthquake scales?
- moment magnitude scale
- mercalli intensity scale
how is the mercalli scale measured?
measured by observations
what eathquake scale is superior and why?
the moment magnitude scale, as its less subjective and theres no room for human error
name the 4 plate tectonic theories?
- slab pull
- subduction
- seafloor spreading#
- mantle convection
describe slab pull?
- newly formed oceanic crust becomes denser and thicker as it cools
- causing it to sink under the mantle under its own weight
- pulling down the rest of the plate
describe subduction?
- 2 oceanic plates move towards eachother, 1 slide under into the mantle
- where it melts in the subduction zone
describe seafloor spreading?
- magma is forced up, creating new oceanic crust
- new crust pushes tectonic plates
what is a mid ocean ridge?
new ocean floor is created as tectonic plate move apart
what is an intra-plate earthquake
earthquakes that occur in the middle or interior of plates
name the 3 primary volcanic hazards?
- lava flow
- pyroclastic flow
- tephra + ash flows
name 4 features of the montserrat volcanoe?
- 19 killed
- 1100 people evacuated
- pyroclastic flow
- lahars
name 4 features of the nepal earthquake?
- landslides
- 7.8 magnitude
- 300 aftershocks
- 900 deaths
name 3 features of the christchurch earthquake?
- liquefaction
- cars 20m underground
- 7.1 magnitude
name 4 features of the boxing day tsunami ?
- 14 countries affected
- 272000 deaths
- 9.0 magnitude
- after shocks
name 6 features of the haiti earthquake?
- 7.0 magnitude
- 14 billion economic cost
- 1 M homeless
- 300,000 deaths
- prison destroyed
- cholera outbreak in refugee camps
name 3 features of the iceland volcano?
- jokulhaups
- disrupted global air travel
- 330 M cost to airline companies
name 5 features of the sichuan china earthquake?
- 125 million economic cost
- 7.6 magnitude
- 1M homeless
- 87000 deaths
- 375000 injured
name 4 features of the tohuku japan earthquake?
- 8.7 magnitude
- 225 billion economic costs
- tsunami
- 6000 deaths
- power plants destroyed, energy prices up
- 75% of infrastructure withstood
what are the 2 parts of the upper mantle?
- lithosphere
- asthenosphere
whats the lithosphere?
thin, solid layer layer where tectonic plates are formed
whats the asthenosphere?
semi molten layer, which tectonic plates lay on
whats the benioff zone?
area where plates make contact and friction occurs, causing earthquakes
what is paleomagnetism?
studying rocks formed by underwater volcanoes in relation to the earths magnetic field
what does the reversal of the earths magnetic field cause?
opposite direction magnetic signature on rock on the ocean floor
whats an island arc?
long chain of volcanoes along a convergent boundary
what causes intra-plate earthquakes?
weaknesses within the plate
whats a hotspot?
area of super heated magma in the mantle, magma plume melts earths crust and forms a volcanoe
what is a plate margin?
area either side of a plate boundary
name 2 primary impacts of earthquakes?
- groundshaking
- crustal fracturing
name 3 secondary effects of earthquakes?
- liquefaction
- tsunami
- avalanche/landslide
what is lava flow?
stream of hot lava
what is pyroclastic flow?
dangerous mix of lava and gases
what is tephra+ash falls?
when rock and ash is blasted into the air
what are lahars?
when ice melts and mixes with ash, causing a mudslide
what are jokulhlaups?
glacial outbursts due to heat
whats the VEI?
volcanic explosivity index
what is the calculation for risk?
risk = (hazard X vulnerability) / capacity to cope
name 4 reasons for an increase in reported natural disasters?
- improvements in monitoring and recording
- increasing population
- climate change
- more impermeable ground
