Hazards - Earth and Environmental science

what 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