2.2 Landslides, earthquakes and tsunamis

2.2 Landslides, earthquakes and tsunamis

1.       What is a landslide?

A geological phenomenon which includes a wide range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments.

2.       Describe the main causes of landslides.

Heavy rainfall saturating the soil, vibrations from earthquakes or undercutting of banks and cliffs from waves or rivers.

3.       In what way can human actions contribute to landslides?

Construction of roads and railways on hillsides along with building works can weaken hillsides and make them more vulnerable during heavy rainfall.

4.       What are earthquakes and how are they measured?

Earthquakes are intra-plate tension where movements occur along cracks and faults in the Earth’s crust.  Earthquakes are measured in magnitude.

5.       What is the main cause of earthquakes in Australia?

The main cause of earthquakes in Australia is inter plate tension

6.       How frequently does Australia experience earthquakes of 5.5 on the Richter scale and why do they usually have minimal impacts on communities?

Every 15 months

7.       List the impacts of the 1989 earthquake on the Newcastle community.

13 people were killed and more than 120 people were injured

8.       Describe the difference between a landslide and an earthquake.

Earthquakes are bigger and effect more people.

9.       What is a tsunami?

A earthquake, landslide or volcano occurs under the sea.

10.   Name three events that will cause a tsunami.
Earthquakes, landslide or volcano

11.   With the aid of a diagram, explain how a tsunami is formed
Sudden shifting of continental places causes earthquakes forcing sea water above to rise, forming waves.

12.   Describe three tsunami warning signs.

Shake, drop and roar

Shake – feeling an earthquake or the ground shake in a coastal area

Drop – the seal level will recede dramatically

Roar – often a tsunami can be heard

13.   What caused in Indian Ocean tsunami of 2004

An undersea earthquake measuring a magnitude of 9.3.

14.   How many earthquake monitoring stations are there in Australia? How long did it take for the India Ocean earthquake of 2004 to be picked up by one of these stations?
There are 23 stations in Australia and it took 20 minutes.

15.   Describe how a tsunami changes as it enters shallow water.

As waves near land they slow to about 45kph, they squeeze upwards, getting taller.

16.   What steps has the United Nations taken to safeguard Indian Ocean communities from the tsunami hazard?

The United Nations created the tsunami warning system

17.   Who is Ted Bryant? What warning does he issue in regard to tsunamis for Australia?

Ted Bryant is a Wollongong university geoscience professor. He predicted that  a tsunami will come soon because every 500 or so years a tsunami occurs in the alpine fault line.

18.    

a)      95 E, 5 N

b)       

ii. India: 2 hours

iii. Africa: 7 hours

iv. Australia: 5 hours

v. Tasmania: 9.5 hours