Earthquakes produce three types of seismic waves: primary waves, secondary waves, and surface waves. Each type moves through materials differently. In addition, the waves can reflect, or bounce, off boundaries between different layers.
More than 2/3 of Central America's agricultural land is used for cattle grazing.
The smallest country in mainland Africa is The Gambia with a total land area of 10,689 km². It is enveloped by its neighboring country, Senegal.
