rocks off the top and erupts again. Just before this happens there are sometimes a lot of earthquakes in the area. This can be a warning to people who live on the volcano that it is about to erupt. The problem is that volcanic eruptions are not predictable and many people die each year when eruptions happen suddenly.
             So why do people want to live near volcanoes? The answer is that volcanic rocks form very fertile soils that are good for growing crops. In crowded countries like Indonesia where there is not much space to grow crops, farming on volcanic soils is vital to keep the population alive. If the molten rock comes out under water then it will cool very quickly. This is happening along the middle of the Atlantic Ocean where lavas are erupting out along huge cracks that run from Iceland in the north down to the Falkland Islands in the south. This is the longest volcanic mountain chain on Earth but not a lot of people know it is there because it is hidden beneath the sea.
             There are also other planets in the solar system with volcanoes on them. Mars has one of the biggest volcanoes - a mountain called Olympus Mons. Scientists believe that all the volcanoes on Mars are inactive now. Venus is almost completely covered in volcanoes. 80% of the planet is peppered with them. But scientists are yet to find a smoking one. One theory suggests that Venus burps out its heat from the mantle every 500 million years in a catastrophic volcanic event which covers the whole planet. The rest of the time it stays dormant.
             1. In volcanic areas - water which is contained within rocks can be heated by the molten rocks which give rise volcanoes. The hot water can be 'tapped' and used for power - this power is called hydrothermal energy (hydro = water and thermal = heat or energy). In Iceland, hydrothermal energy is used in greenhouses to grow tomatoes and bananas! It can also be used to generate steam which in turn can power turbines and produce e...