Earthquakes produce shock waves, which can travel inside the Earth. They can damage buildings and cause tsunamis. THese waves are called seismic waves and can be detected by seismometers.
There are two main types of seismic wave - P-waves and S-waves.
P-waves (primary waves) are longitudinal and travel through both solids and liquids.
S-waves (secondary waves) are transverse waves and travel through solids but not through liquids, they travel more slowly than P-waves.
After an earthquake occurs, the waves are detected all over the world, as shown in the diagram.
P-waves are detected in most places, so this means they can travel through the solid crust and mantle, and the liquid outer core and inner core.
S-waves are only detected closer to the epicentre. This means they can pass through the solid crust and mantle, but they can't pass through the liquid outer core.
Scientists believe that we are experiencing global warming, which may have serious implications for the Earth in the future. Three factors that contribute to global warming are:
- increased energy use in homes and industry
- increaased carbon dioxide (CO2) emissions from fossil fuels
Weather patterns are affected by human activity, as well as by natural phenomena, for example:
- dust from vocanoes reflects radiation from the Sun back into space, causing cooling.
- dust from factories refelects radiation from…