F2 Why do earthquaks occur?

The cause of earthquakes
Convection currents【岩漿對流】 drive the plates to move and pressure builds up along the _______________ plate boundaries【板塊邊界】. When the pressure becomes too large, the plates _______________ displace【移位】 and fracture【斷裂】. As a result, huge amount of energy is released【被釋放】 in the form of _______________ seismic waves【地震波】 and shakes【搖動】 the ground , causing an earthquake.

Earthquakes related keywords

1. _______________ Focus【震源】 is the point where a plate displaces and energy is released.
2. _______________ Epicentre【震央】 is the point on the ground surface vertically above the focus.
3. _______________ Seismic wave【地震波】 is the energy released from the focus and travels in all directions.
4. _______________ Depth of focus【震源深度】 is the vertical distance between the focus and the ground.

Convection currents【岩漿對流】 drive the plates to move in three different ways – _______________ moving towards each other, _______________ moving away from each other and _______________ sliding past each other.

Most earthquakes occur along the plate boundaries. The two main earthquake zones【地震帶】 are the _______________ Circum-Pacific Belt【環太平洋帶】(responsible for 90% of the world’s earthquakes) and the _______________ Alphine-Himalayan Belt【阿爾卑斯-喜瑪拉雅山帶】.

The Circum-Pacific Belt is also known as the _______________ Pacific Ring of Fire【太平洋火環帶】 since volcanic activities【火山活動】 happen very frequently【頻繁地】 there.