Earthquakes

Question 1

Where do earthquakes occur?

Answer 1

• most are found along all kinds of plate boundaries (divergent, convergent, transform)
• occurs frequently along convergent boundaries, esp along Pacific Ring of Fire
• found in clusters

Question 2

Define earthquakes

Answer 2

• a vibration or tremor of earth’s surface

- caused by sudden release of energy stored in rocks in Earth’s crust

Question 3

Why do earthquakes occur?

Answer 3

• tectonic plates move, exert friction on one another, cause pressure to build up at boundaries
• pressure gradually builds up in plates, energy stored up in earth’s crust
• rocks can no longer contain pressure, energy released
• energy radiates out thru crust, onto Earth’s surface, in form of seismic waves

Question 4

Why earthquakes do not occur in Singapore

Answer 4

-sg not near plate boundaries, surrounded by Indonesia and Malaysia

Question 5

Characteristics of earthquakes

focus, epicentre, seismic waves

Answer 5

• refer to focus, epicentre, magnitude
• earthquake radiates energy in form of seismic waves
• seismic waves radiate out from a point of sudden energy release called the focus
• point on the earth’s surface directly above the focus is the epicentre

Question 6

Characteristics of earthquakes

aftershocks

Answer 6

• after earthquake event, stress frm ground within earth’s crust may cause smaller earthquakes called aftershocks to occur along fault line
• series of aftershocks may occur for several months after initial earthquake
• some aftershocks nearly as powerful as original earthquake
• characteristics of earthquake described by referring to its strength/ energy released by it