Studied by 10 peoplewhat are earthquakes?
a sudden violent shaking of the ground, typically causing great destruction, as a result of movements within the earth's crust or volcanic action.
what are volcanoes?
an opening in the Earth's crust through which lava, ash, and gases erupt
what is a tsunami?
a long, high sea wave caused by an earthquake or other disturbance
what is built up in the crust that causes an earthquake?
continual elastic energy
what faults are caused at transform boundaries?
strike-slip faults
what is the richter scale?
a logarithmic measure of the strength of earthquakes
what are the 2 scales used to measure magnitude?
richter scale and moment magnitude scale (Mw)
what are the 3 types of seismic waves?
primary, secondary, and surface (love and rayleigh)
what direction do p waves move?
back and forth in the direction of the path of propagation
what direction do s waves move?
move back and forth perpendicular to the direction of propagation
what direction do love waves move?
move parallel to the Earth's surface and perpendicular to the direction of wave propagation
what direction do rayleigh waves move?
move in an elliptical motion, producing both a vertical and horizontal component of motion in the direction of wave propagation
what are the 6 hazards related to earthquakes?
ground motion, liquefaction, landslides, fire, floods, tsunamis
why are deep submarine volcanoes always effusive?
water pressure
what viscosity is seen in effusive volcanoes?
low viscosity
what are the 5 hazards of volcanoes?
ash flow, lava flow, pyroclastic flow, lahars, poisonous gas
what are pyroclastic flows?
explosive columns of volcanic debris, ash and hot gases create fast flows of extremely high temperatures
what are lahars?
mixture of volcanic material and water that forms a mudflow
example of ash flow
Eruption at Mount St Helens (1980)
Collapse of one flank of the volcano that left the north of the volcano devastated
example of lava flow
Kilauea (2022)
111 million cubic meters of lava flow
pyroclastic flow
Mont Pelee in Martinique (1902)
Demolished the coastal city of St. Pierre
lahar
Eruption at Mount St Helens (1980)
Icy melt water merged with ash, causing a lahar
what is an effusive eruption?
an eruption wher lava steadily flows out of a flow
what is an explosive eruption?
build up of pressure that results in an explosion of gas, ash and magma releasing projectile, particulate matter
what determines magma type?
→ plate boundary type
→ pressure levels
→ temperature
→ minerals present in rock
what is a hazard?
a potential source of harm
what is a disaster?
a serious problem that causes wide spread human, material, economic or environmental loss which exceeds the ability of the affected community or society to come using their own resources
what are the most important factors in determining if a hazard is a disaster?
population density and the built environment of a disaster zone
what is the Wadati–Benioff zone?
a planar zone of seismicity corresponding with the down-going slab in a subduction zone
what does the VEI measure?
volume of the erupted pyroclastic material called tephra
what gases are related to asphyxiation?
carbon monoxide and carbon dioxide
what layers of the atmosphere can ash enter?
stratosphere and sometimes troposphere
what chemicals from explosive volcanoes break down ozone?
chlorine and fluoride
what does sulphur dioxide form when it mixes with water?
sulphuric acid
what does frozen sulphuric acid become?
sulphate aerosols
what is radiative forcing?
the difference between the amount of energy from the Sun radiating to Earth and the amount radiated back into space
how long can a negative radiative forcing last after an eruption?
2-3 years
what plates, vei and year was mount st helens
north american/juan de fuca (subduction), vei 5, 1980
how much did mount st helens cost?
$1.1 billion US dollars
what plates, vei and year was mount pinatubo
eurasian/philippine plate, vei 6, 1991
how much did mount pinatubo cost?
$250 million in damages
what climatic phenomena + their impact on a local area do we need to know?
hail, east coast low, droughts, floods, bushfires
what climatic phenomena do human behaviours contribute to?
droughts, floods, bushfires, landslides
what causes drought?
El Niño Southern Oscillation (ENSO)
what is the location example of droughts?
The Macquarie Marshes in Northwestern NSW
what causes flooding?
la nina, negative indian ocean dipole event
what is the location example of flooding?
murray-darling basin
what is the location example of hailstorms?
Northern Rivers district in New South Wales
what causes an east coast low?
a temperature contrast between the warmer Tasman Sea and cooler continental landmass
what is the location example of east coast lows?
northern beaches of sydney
what is the location example of bushfires?
blue mountains national park
how are volcanoes predicted?
three-dimensional imaging
seismic data
early-warning systems
groundmovement data
analysis of historical data
what technologies fall under three-dimensional imaging?
tiltmeters
strain meters
GPS
InSAR
what does InSAR stand for
interferometric synthetic aperture radar
what technologies fall under seismic data?
seismographs, tomographs
what technologies fall under gas monitoring?
correlation spectrometer (COSPEC)
what location examples fall under gas monitoring?
Mount Etna (Italy),
Sakurajima (Japan)
what location examples fall under historical data?
meep
how are earthquakes predicted?
ground movement detectors
anomalous animal behaviour
strain meters
what technologies fall under ground movement detectors:
seismographs, GPS
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