5. Other Seismic Hazards

Question 1

Soil Liquefaction

Answer 1

When soils contain high quantity of water are violently shaken and lose strength and behave like a fluid
Soil becomes weaker and easier to deform, more likely to subside

Question 2

Landslides and avalanches

Answer 2

Can be caused when shaking dislodges rock, soil, or snow and move quickly downslope due to gravity

Shaking can also loosen ground material, making it easier for water to infiltrate, weight of extra water triggers landslide

Question 3

Tsunamis overview

Answer 3

Usually at destructive plate boundaries
Giant sea waves generated by shallow focus underwater earthquakes-> large movements of seabed which cause displacement of large volumes of water

Question 4

Tsunami characteristics

Answer 4

Greater movement of seafloor greater volume of water displaced, bigger wave

More powerful closer to the coast 
Travel fast (700km/h) 
Long wavelength 
Low wave height in open ocean 
As they reach shallow waters their wave height rapidly increases (over 25m)

Question 5

Tsunami warnings

Answer 5

Wave trough in front of the tsunami results in a reduction of sea level
Can be triggered by large volcanic eruptions

Question 6

Impacts of tsunamis

Answer 6

Buildings, roads, bridges and trees washed away
Large flooding of areas, large death tolls, wide scale damage to properties

Freshwater ecosystems can be flooded, killing animals and Stalinising the water and soil-> crops difficult to grow

Question 7

Indian Ocean tsunami 2004

Answer 7

Magnitude 9-9.3 earthquake
Indian plate slid under Burma Plate which caused massive tsunamis caused massive tsunamis
Warnings were too late

Question 8

Primary Impacts of tsunami

Answer 8

Up to 300,000 dead
Vegetation and topsoil removed
Infrastructure destroyed
Coral settlements devastated

Question 9

Secondary Impacts of tsunami

Answer 9

Widespread homelessness 500,000 were forced into refugee camps
Economies devastated, Thailand the cost to fishing industry was £226 million
Negative multiplier effects weakened economies further

Water supplies and soils contaminated by saltwater
Gap between rich and poor increased

Question 10

Immediate responses

Answer 10

Massive international relief efforts, 160 aid organisations and UN agencies
Foreign military troops, eg Australian Air Force improved air traffic control

Question 11

Long term responses

Answer 11

Large scale programmes of reconstruction but many were still left in tents 1 year on

Existing government prejudices were highlighted eg India underclass ignored

Sirens on beaches in Thailand but poorer communities receive warnings by radio

education and practice drills/evacuation established