Secondary Vents are extra vents that the lava seeped through Secondary Cones are built by lava and are on the volcano. The risks to people and property from volcanic eruptions are being destroyed by lava. Some risks to people are suffocation to the gas cloud. You can predict volcanic ruptures because there will be ground shaking, increase in temperature and the Earth’s surface will began to bulge. What role have volcanoes played in the evolution of life on the planet?
This type of magma is dangerous because it has a tendency to plug the volcano, trapping gasses which build pressure and eventually erupting violently! This is evidenced in subduction volcano's like Mt. St. Helens and Krakatoa are common types of these volcano's. The magma plugs the volcano which creates and increase in pressure and latent heat which eventually creates a huge explosion. They release enormous amounts of energy and create eruption columns of gas and ash that can rise up to 50 km (35 miles) high at speeds of hundreds of meters per second.
To what extent to you agree with the view that the hazards resulting from earthquakes and volcanic activity cannot be managed but merely adapted to. Earthquakes and volcanic activity are both nature disasters that human can’t control when or where it will happen and it may cause lots of death and economic loss. There is no way that we can stop it from being happened but we can definitely try to adapt it by many different ways. Firstly, volcanoes are found at destructive and constructive plate margins. At destructive plate margins, the oceanic plate goes under the continental plate due to it’s more dense, which is a process known as subduction.
The first factor that must be considered is the viscosity of the magma. This can determine how powerful an eruption is and what shape the volcano eventually becomes. Viscosity can be affected by three main factors, firstly, the higher the temperature, the lower the density of the magma, causing it to flow more easily. Secondly, the greater the amount of dissolved gases in the magma, the less viscous it will be, and lastly the higher the silica content, the more viscous it will be. Thicker, more viscous magma has a greater potential for explosive eruptions and therefore represent the greatest potential hazards.
Analyse the factors that cause differences in the hazards posed by volcanoes around the world (40 marks) June 2013 Volcanoes are forms of major extrusive activity and are openings in the Earth’s crust where molten rock and gases reach the surface. The eruption of volcanoes throws out lava, rocks, ash and gases in various proportions. How hazardous a volcano is, depends on a variety of human and physical factors that work in conjunction to determine the level of damage a volcano can have on the human population. The location of a volcano is a large variable which determines the nature of its eruption. Volcanoes are found mainly in three locations, at constructive and destructive plate margins and at hotspots.
At constructive boundaries where plates are moving apart from one another, basaltic lava is erupted between the gaps. This type of lava is not very viscous due to its low silica content. This is because no subduction of crust is involved so the lava is not made of melted lithosphere but has risen from the mantle itself. The low viscosity of this lava causes it to flow very far before cooling and solidifying. This forms shield volcanoes with very gentle slopes and a much wider base than more conical shaped volcanoes involved with convergent plate margins.
I will be discussing factors that cause differences in hazards posed by volcanoes. I believe the most important factor is the location of a volcano and the type of volcano. The most explosive and therefore dangerous volcanoes are found on destructive plate boundaries (Over 80% of the worlds volcanoes occur at these boundaries) for example the eruption of the Nevado del Ruiz in Colombia on the 13th November in 1985 which killed over 25000 residents of Arenas and Armero. At destructive plate margins, the oceanic crust is denser than continental crust and is therefore subducts under the continental crust. Due to high temperatures in the mantle of around 3000 degrees centigrade, this oceanic crusts melts and then rises due to the convection currents in the aesthenosphere .
Discuss the view that the impact of earthquake hazards depends primarily on human factors  An earthquake is a tremor or shockwave in the earth’s crust that is caused by the sudden movement of the crust, resulting in the earth shaking. Most earthquakes are a consequence of tectonic plate movement by tension causing a sudden release of energy or rubbing. These normally occur at plate margins or along fault lines and can cause hazards which need to be prevented where possible. Earthquakes can therefore occur at all plate boundaries, destructive, constructive and conservative but the most damaging tend to happen at destructive margins where the earthquakes have a high magnitude due to the rubbing of the oceanic and continental crusts. A hazard is a natural event that has the potential to effect both life and property.
Plate tectonics and Associated hazards Analyse the factors that cause differences in the hazards posed by volcanoes around the world. (40 Marks) Using case studies we can clearly see the differences in the hazards that volcanoes pose. A hazard is a situation that poses a level of threat to life, health, property or environment. The level of hazard posed by different volcanoes can very greatly, from a weak eruption with minimal impact that causes little damage, to a violent and life threatening explosion. Most of the sixty-plus volcanoes that erupt each year are low risk, however a combination of factors can cause a volcano to be a serious hazard.
Evaluate how plate tectonics theory helps our understanding of the distribution of seismic and volcanic events. [40 marks] In this essay, I will weigh up several arguments through the use of case studies and demonstrate how the tectonic theories support our understanding of the distribution of seismic and volcanic activity. Seismic is a word we use to show that something is caused by an earthquake or earth vibration. In the world, there are 15 major tectonic plates which are always moving and therefore are always moving against one another on plate margins. This knowledge of plate margins and their movement against one another can help us to understand the distribution of seismic and volcanic events and this is because the majority of events are associated at these plate margins.