describe the main types and features of volcanoes and earthquakes

•there are two main types of volcanoes -stratovolcanoes and shield volcanoes 

           

•characteristics of stratovolcanoes

          •steep conceived sides means that the viscous lava doesn't flow far

          •there are alternating layers of lava and ash 

          •they are dormant due to the time it needs to build up pressure 

          •form on destructive plate boundaries

•characteristics of shield volcanoes 

          •they are very large because the lava is very runny and takes a while before turning solid

          •only form on constructive plate boundaries

         

•features of volcanoes:

            •craters: •are circular depressions and both may have them at the summit 

                        •formed by the explosive ejection of material from a central vent 

          •calderas: •a caldera is a huge crater when a volcanic cone collapses into a partly empty magma chamber after a powerful eruption

          •parasitic cones: •they are small cones which develop on the side of a bigger volcano

                                               •they form when the main vent becomes blocked and the magma finds another outlet

          •the point within the Earth where the earthquake originates is called the focus

          •the point on the Earth’s surface directly above the focus is called the epicentre 

          •the shallower the focus, the more intense the earthquake 

                    •there are two scales: •the Richter scale for magnitude (total energy released/10) 

                                                       •the Mercalli scale of earthquake intensity /12