Tectonic Hazards-Earthquakez

Question 1

When do earthquakes occur

Answer 1

• When there is a sudden shift of a tectonic plate at a plate margin
• At conversion margins oceanic to oceanic crust subducts under continental crust, immense friction
• conservative equals plates moving alongside each other
• diverging equals plates pulling away from one another (earthquakes tend to be of low mag)

Question 2

Tell me about liquidation

Answer 2

• occurs when soil which is waterlogged is shaken during an earthquake
• buildings removed collapsed or sunk into soil
• when the shaken stops, the soil become solid again and buildings and people are stuck/ in gold into the soil
• causes damages to settlement and transport networks and deaths

Question 3

Tell me about landslides

Answer 3

• In areas where material on a slope is unstable
• vibrations will be enough to overcome any friction and mass movement occurs
• fracturaes rocks can slide down a slope
• buildings and transport networks a damaged by falling rocks

Question 4

Tell me about ground shaking

Answer 4

• vibrations radio outwards from the focus of an earthquake in the form of P and s waves
• generally, the amplitude of ground shaking will decrease with distance from the epicentre
• soft rocks near the surface and thick deposits of soil increase amplitudes
• causes destruction to buildings, transport and networks.
  -causes Rupture of mains and water gas pipes. Fires due to bust gas pipes
• deaths from falling debris

Question 5

Tell me about how tsunamis are caused

Answer 5

-When an earthquake becomes underwater the sudden shift in the seafloor causes a displacement of water
- when a tsunami enters shallow water, the wave height increases greatly

Question 6

Tell me about DART

Answer 6

-NOAA has developed DART
- this is a real time monitoring system that provides data for forecasting tsunamis
-DART systems combines a surface buoy and sensor on the ocean floor
- sensor detects changes on water pressure and seismic activity- transports a data back to the surface
- the buoy signals via satellite to tsunami warning stations

Question 7

Tell me about environmental impacts

Answer 7

• destruction of forests (p)
• drowning of animals (p)
• fires (s)
• pollution of toxic waste and substances may be released into the atmosphere (s)

Question 8

Tell me about economic impacts

Answer 8

• destruction of industry (p)
• destruction of buildings (p)
• fires (s)
• destruction of transport (p)
• destruction of settlements (s)

Question 9

Tell me about social impacts

Answer 9

• injuries (p)
• homelessness (p)
• disease as sewage mixes with water supply (s)

Question 10

Tell me about the physical hazard characteristics

Answer 10

• magnitude
• predictability
• frequency
• duration
• speed of onset
• Areal extent

Question 11

Tell me about mitigation of tsunamis and earthquakes

Answer 11

• land use zoning- prevents buildings in areas prone to liquidation and tsunamis
• design of earthquake resistant buildings
• early warning systems- educate people so they know how to receive early warning alerts, know evacuation routes and shelters, and prepared to run to higher ground
• emergency mobile alerts
• in New Zealand they use blue lines around the edges of evacuation zones- people know where to go
• exercises and drills to make sure people are tsunami ready