10. Tsunamis

Question 1

What happens to wave height?

Answer 1

Low wave height (< 1m) but on reaching the shore they can reach to over 25m.

Question 2

What is the wavelength like?

Answer 2

Long wavelength -> in open water can be anything from 100-1000 km

Question 3

What are wave speeds like?

Answer 3

Reach speeds between 640-960 km/hr

Question 4

What does a tsunami usually consist of?

Answer 4

A series of waves, with first not always being the biggest

Question 5

How long between each wave?

Answer 5

Between 10-60 mins

Question 6

What happens upon approaching the coast?

Answer 6

On approaching the coast, especially if funnelled into an inlet, they will slow down and pile up a massive wall of water.

Question 7

What are the factors affecting the severity of a tsunami’s impacts?

Answer 7

• education
• population density
• economic development -> LICs have less money to build defences/ stronger buildings
• height of waves and distance travelled
• length of event at source
• coastal geography, both offshore and on coastal area
• coastal land use and population density
• extent to which warnings could be given
• magnitude

Question 8

What happens in the first stage?

Answer 8

Generation of a tsunami in deep ocean -> tsunamis are difficult to detect by ships due to small wave height and long wave length

Question 9

What happens in stage 2?

Answer 9

Nature of the waves will depend upon:
- Cause of the wave e.g. eruption or earthquake
- Distance travelled from the source, as energy is lost as they travel
- Water depth over route affects energy loss through friction
- Offshore topography and coastline orientation

Question 10

What happens in stage 3?

Answer 10

Landfall -> death and destruction will depend upon land uses, population density and any warning given, as well as the physical geography or relief of coastal areas

Question 11

Economic short term impacts

Answer 11

• Infrastructure destroyed

Question 12

Economic long term impacts

Answer 12

• Fishing, agriculture and tourism impacted -> 44% of population living in Aceh province, Indonesia lost childhoods
• £226 million cost to fishing indistry
• Gap between rich and poor increased

Question 13

Short term social impacts

Answer 13

• Up to 300,000 died
• Infrastructure destroyed
• Coastal settlements devastated

Question 14

Medium term social impacts

Answer 14

• Flimsy wooden buildings had no chance

Question 15

Long term social impacts

Answer 15

• PTSD
• Survivor’s guilt
• Widespread homelessness -> 500,000 forced into refugee camps

Question 16

Short term environmental impacts

Answer 16

• Vegetation and top soil were removed, wildlife devastated
• Floodwater laden with debris
• Water supplies and soils contaminated y salt water

Question 17

Long term environmental impacts

Answer 17

Tsunami swept over Maldives islands and rendered them uninhabitable