1. Earthquakes are caused by forces deep within the earth .
2. When the Earth shakes ,buildings can collapse and people can be buried inside .
collapse /kə'læps/ 倒塌；瓦解；暴跌 vt. 使倒塌，使崩溃；使萎陷；折叠
3. An explosion is a rapid ,violent release of energy .
4. Explosions can be cause by chemical reactions, such as inside an engine .
5. A spark can ignite a mixture of gases,and release energy for good or destructive purposes.
ignite /ɪɡ'naɪt/ 点燃；使燃烧；使激动 vi. 点火；燃烧
6. Accidents are often caused by people doing foolish things, or by not being careful.
7. One major cause of accidents is driving too fast.
8. Accidents with fire can be very serious, and can result in very painful injuries.
9. Epidemics are the rapid spread of a disease,such as the flu or Ebola.
Epidemic /,ɛpɪ'dɛmɪk/ 流行病；蔓延
10. Throughout history, epidemics have killed millions of people.
Throughout /θrʊ'aʊt/ 自始至终 遍及
11. Storms are caused by changes in the atmosphere, resulting in high winds and heavy rain.
12. Thunderstorms are caused by electric charges in the atmosphere, that produce lightning, which can cause forest fires.
13. Some storms cause flooding, and major damage to homes and cities.
