earth hazards are hazards such as flooding, earthquakes, volcanic eruptions and which are initially caused by earth processes. However, it is often the case that human factors can be a major cause in the impacts of these hazards as they increase the risk posed by these earth hazards. physical causes would include the processes that initially cause the disaster such as high rainfall, seismic activity, location of the hazards and the structure of the rocks in the earth’s surface. human factors are broad and can range from the lack of preparedness for a disaster to increasing the risk such as urbanisation and building large highly populated cities in vulnerable areas.
firstly, lets take volcanoes. a volcanic eruption varies in its physical cause depending on the type of volcano but generally the volcanic eruption is caused by the buildup of magma inside the volcano’s magma chamber that eventually comes to the surface either gradually, as in the case of a shield volcano or suddenly such as with a composite volcano. the type of magma influences whether the eruption is explosive or not and this is due to the location of a particular volcano. a composite volcano which is typically more explosive occurs on a destructive plate boundary whereas as a shield volcano occurs on a constructive plate boundary. therefore the initial cause of any volcanic eruption is the natural processes of the volcano itself. however, the volcano is only a hazard when it comes into contact with humans, which is the case for most earth hazards. around the world, humans have chosen to live near a volcano for many reasons such as the fertile land or the benefits of tourism created by the volcano so therefore they are at risk from a volcanic eruption when they occur. however there are some examples around the world where humans have increased the risk through political difficulties. Mount Nyiragongo in the DRC is a volcano that overlooks the city of Goma. this volcano is one of the most active in the world due to its location on a hotspot and so the city of Goma and the surrounding area are at a high risk of an eruption and as a result there have been many attempts to monitor the volcano’s activity to give a warning if there was to be a major eruption. although volcano monitoring is very advanced, it has been difficult to monitor this volcano as the slopes of the mountain are controlled be rebel groups who see it as an important look out over Goma. therefore, the political instability of the country has meant that it is too unsafe for scientists to monitor the volcano and any attempts in the past have been stopped as the equipment was stolen by looters. therefore should an eruption occur then the impacts on Goma will be much higher than normal.
earthquakes are slightly less to do with physical factors in my opinion than volcanoes. although no earthquake can happen without the initial seismic activity created by the build up of pressure in the earth’s crust along a plate boundary or a fault line, the actual earthquake is not the cause of damage to human lives and property. If an earthquake occurred in the middle of the Atacama desert then even if the magnitude was very great the risk of the earthquake would be very low as the population density and urbanisation of the area is minimal. however if this earthquake occurs in a densely populated area such as the city of Istanbul then the risk of the hazard would be far greater. therefore human factors such as having highly urbanised or populated areas on an active fault line can increase the impacts of the earthquake. however, these areas that experience lots of seismic activity are more likely to be prepared for a major earthquake which is the case of Japan which is located in one of the most tectonically active areas of the world. but as a result Japan has one of the highest number of earthquake-proof buildings in the world and they have a very advanced warning system of messages that are programmed to appear on TV screens when an earthquake is about to occur along with well rehearsed earthquake drills meaning people know what to do in an earthquake. this preparation meant that in the earthquake that struck Japan in 2011, no lives were lost to the earthquake, which is a rare statistic when it comes to earthquakes. the deaths that did occur were due to the tsunami that followed which was a much larger and rarer hazard than an earthquake. whereas in the Haiti earthquake of 2010 the death toll was 316,000 which was due to the poor quality of the buildings, and the lack of preparedness of the country for an earthquake which was due to the lack of funding for these measures but also because the country hadn’t experienced a major earthquake for 168 years meaning people didn’t think it was likely an earthquake could occur and that it would not be financially viable to prepare for something that had not happened in a long time.
Flooding is an earth hazard that has a wide mix of causes and these vary a lot depending on the location of the flood. flooding can be caused by physical factors such as intense or prolonged rainfall, small river valleys and the steep relief of land. however human factors such as urbanisation, high population densities, poor defences and building on vulnerable areas such as floodplains or reclaimed land. often with floods it is a mix of physical and human causes but I feel that human causes contribute most to the impacts of flooding. The recent UK winter storms have caused large amounts of flooding in many areas of the country. the reason for the floods is primarily the prolonged rainfall that was caused by the constant low pressure systems that came over the UK one after the other meaning the ground couldn’t recover from the rainfall quick enough resulting in the ground becoming over saturated. this meant that rivers were constantly bursting their banks and low-lying flat areas of land were constantly underwater, as of the case of the Somerset levels. however, as i mentioned earlier an earth hazard only becomes a hazard when it interacts with humans. therefore the flooding can be argued to be largely due to human factors. due to the growing population of the UK, more housing is needed and this means that the risk has to be taken to build on land vulnerable to flooding such as floodplains. in the ideal world to stop this we would ban anyone from living on floodplains however due to the demand for housing this is not realistic. also the Somerset levels is largely made up of reclaimed land that was drained in the 1600’s to create more land to live and work on. some areas of this land are below sea level and many areas are flat and vulnerable to any flooding. as a result defences have been created to try to reduce the risk of flooding here such as straightening the river channels, building levees and recently dredging. however, whilst these strategies can prevent flooding they can only do so to a certain extent as there is only so much a levee can take, for instance. also, in other areas of the world such as in Bangladesh which floods regularly due to the monsoon weather patterns, the flooding has been increased by deforestation around the river’s upper course such as in the Himalayan slopes which has meant that less water is intercepted and absorbed be vegetation resulting in a higher level of surface run off. this has meant that the volume of water is greater and therefore the impacts of flooding are becoming more extreme.
I feel that the impacts of earth hazards are largely due to human factors. although physical factors are important as they provide the initial cause of the hazard, in many cases it is the human factors that cause the extremity of the impacts of these hazards to increase. the most common human factor in my opinion is the fact that we choose to live in these vulnerable places. it is unrealistic to move an entire city away from a fault line or stop much-needed cheap homes to be built on a floodplain as the demand for them often out ways the risk of an earth hazard. therefore we have learnt to adapt to these hazards and prevent the impacts of them as best we can.
most of the above information was sourced from notes taken in my A level geography lessons. these notes are available on http://www.getrevising.co.uk. please contact me if you wish to see any specific resources that were used on this page and i will give you the link to the appropriate resource via getrevising.