Tsunamis

Question 1

In the open ocean..

Answer 1

Tsunamis have a long wavelength (more than 100km) and a low height (under 1m), travel at over 700km h-1

Question 2

On reaching shallow water..

Answer 2

They increase rapidly in height

Question 3

What is often the first warning for coastal populations

Answer 3

The wave trough in front of the tsunami, which causes a reduction in sea level, known as drawdown

Question 4

The event usually consists of ..

Answer 4

A number of waves

Question 5

When a tsunami reaches land, its effects will depend upon

Answer 5

• height and distance of waves
• length of the event that caused it
• extent of warnings
• coastal physical geography
• coastal land use and population density

Question 6

How far inland are the effects of most tsunamis felt

Answer 6

500-600m

Question 7

Tsunami case study

Answer 7

Generated by the explosion of the volcano Krakatoa in 1883

Drowned 35,000 people

Question 8

Where are 90% of all tsunamis generated within

Answer 8

The Pacific basin and are associated with the tectonic activity taking place around its edges

Question 9

Where are most tsunamis generated at

Answer 9

Convergent plate boundaries where subduction is taking place, particularly off the Japan-Taiwan island arc (25% of all events)

Question 10

Case study of tsunami

Answer 10

July 2006
South Java coast
Generated from a 7.7 magnitude earthquake
600+ deaths

Question 11

Indian Ocean tsunami

Answer 11

2004
Indo Australian plate subjects under the Eurasian plate
300,000 killed 
Homeless 
Low cost less than $5 billion 
West side received warnings 
Warnings system now set everywhere