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.
Each year, around 60 major volcanoes erupt globally. How hazardous each eruption is depends on a variety of physical and human factors. This essay will analyse how physical volcanic properties interact with human variables to make certain volcanoes more hazardous than others. This will be identified through the numerous recorded eruptions from different countries at different stages of development. Since the degree of impact an earthquake has is measure on both the Richter and the Mercalli scale, it must be reasonable to assume that the power of an eruption is representative to the degree of how potentially hazardous the event may be.
When the eruption did occur it was seen as explosive as it produced large volumes of acidic lava, ash, pyroclastic flows and steam. However, volcanoes at constructive plate margins or hot spots are generally seen as less explosive. They produce continuous, yet gentle, eruptions of lava, such as the formation of the
These types of lava are very viscous due to its high silica content. This is because the lava rises from the subduction zone through continental lithosphere which has a low density and is filled with air spaces containing gases which become incorporated into the lava. This very viscous lava often blocks off vents of volcanoes and when the pressure building up in the vent is eventually released, the top of the volcano can be blown off leaving a huge crater, such as in the 2002 eruption of Mount Etna in Sicily. When the two plates involved are oceanic, explosions tend to be less violent than this as the melted lithosphere which forms the lava is denser and so contains fewer gases. At constructive boundaries where plates are moving apart from one another, basaltic lava is erupted between the gaps.
Just like the characteristic of a rock, climate also plays a role in the rate in which a rock will break down. With that being said, rocks that are exposed to a wet/ moist climate are more susceptible to chemical weathering. Thus, the rocks in this type of climate will decompose at an accelerated rate. On the other hand, dry climates are more vulnerable to mechanical weathering, which has a slower weathering rate. All in all, areas with warm temperatures will have faster chemical reactions, so, weathering in the tropics is rapid.
In the last 30 years there have been multiple examples of where volcanic and seismic events have had an impact on both MEDCs and LEDCs. Some of these include the 2010 earthquake in Haiti and the 2011 Japanese earthquake and the consequential tsunami. In this essay I will show how the impact of volcanic and seismic events have a greater impact on poorer countries than on richer countries. Although prevention of either a volcanic eruption or a seismic event isn’t possible, it is possible to manage them and reduce the overall impact. In theory, this is easier for MEDC’s due having more advantaged technologies and more money available to spend on monitoring the ‘danger zone’ and then warning and planning for the hazard.
Using the meteorological data recorded over time, predictions can be, fairly accurately, made concerning average temperatures as well as common seasonal wind and rain patterns. Seismographs work for geologists in the same manner. There is no possible way to predict the exact moment an earthquake will occur but just as the air temperature an estimate or time frame can be assumed. As technology progresses time will allow for better predictions that may save many lives. The geological energy created by the friction of our planet’s tectonic plates places stress on millions, if not more, every year.
Gases dissolved in magma provide the motive force of volcanic eruptions, sulphurous volcanic gas and visible steam are usually the first things noticed on an active volcano as well as others that escape unseen for example through hot fumaroles, active vents, and porous ground surfaces. The limitations of taking these samples are remote location of these sites, intense and often hazardous fumes, frequent bad weather, and the potential for sudden eruptions can make regular sampling sometimes impossible and dangerous. Measuring gases remotely is possible but requires ideal weather and the availability of suitable aircraft or a network of roads around a
To what extent can preparedness and planning mitigate the effects of volcanic hazards? (40 marks) Volcanic activity happens across the surface of the globe and naturally hazards occur too. A hazard is a situation that poses a level of threat to life, health, property, or environment. It is easy to locate volcanoes, but it is very difficult to predict exactly when activity will take place, particularly a major eruption, this makes it difficult to prepare or plan for one. There is a very big difference that helps prepare for a volcanic hazard and that is whether you are in a MEDC or a LEDC.
The thick glass is more likely to crack since glass is a poor conductor of heat. In a thin glass, the heat passes more quickly from the glass into the surrounding air, causing the glass to expand equally. When hot water is poured into a thick glass, the inner surface expands, but the outer surface does not. It is this extreme stress on the glass that causes it to crack 20. What relation would your father's sister's sister-in-law be to you?