Directly underneath the Earth’s 1. ______ there are layers of 2. _______, which, because of the high temperatures at the core, are melted to form magma. Magma contains various gases – predominantly carbon dioxide, 3. _________ and sulfur dioxide. It is stored in 4. ___________ that are sealed beneath a lid of solid rock. Due to its liquefied state, the magma is less dense than the rock above it and begins to rise. Simultaneously water vapor escapes as 5. _______, increasing the relative density of the carbon dioxide and 6. _________. Over time these gases expand to 7. _________their original size, increasing the pressure on the chamber lid to such an extent that an eruption occurs. This is similar to when you shake a soft drink, and it explodes when opening the lid – by shaking it you are separating 8. _________molecules, causing a build-up of gas and pressure. When magma is released – through the ruptures in Earth’s crust we call volcanoes – it is known as 9._________, which is hot as 1100 degrees Celsius. Typically, it will also form pyroclastic clouds: cascades of hot ash, gas and molten rock fragments, which are around 1000 degrees Celsius and travel around 700 km/h.
