A hazard can best be defined as a ‘situation that poses a level of threat to life, health, property or the environment.’ The overall impact of earthquakes as a natural hazard varies greatly from one place and timeframe to another. As do the types of hazards, which are categorised into primary and secondary. Primary hazards, created by the direct seismic energy of the earthquake, could include liquefaction, slope failure and tsunamis. These primary hazards can in turn trigger secondary hazards such as floods, fires, disease and destabilisation of infrastructure. A number of factors play a part in determining the severity of these hazards; the majority of which relate to the spatial and temporal circumstances surrounding an earthquake.
For me, the most influential spatial factor is where the earthquake occurs in relation to the levels of development of that area. More economically developed countries (MEDC’s) tend to cope better with the hazard of earthquakes than less economically developed countries (LEDC’s) because they have all the necessary resources to survive the effects of an earthquake at their disposal. Like many MEDC’s, Japan has a highly-skilled labour force working in world-leading economic and scientific sectors.
This means they possess the knowledge, expertise and financial support to plan, predict (to some extent!) and prepare for natural hazards. In Kobe, every building is subject to stringent specifications designed to be earthquake proof and important city landmarks, Kansai International Airport and Akashi Suspension Bridge, were built using high-tech construction materials. Government departments are responsible for managing and coordinating emergency responses and educating the public about natural hazards. As a result, the city holds regular earthquake drills in public places and emergency services practice through simulations. Although in MEDC’s, the higher level of development and infrastructure means the total cost of the hazard is usually higher, the total economic cost of Kobe’s earthquake was believed to be around $100 billion US dollars, 2.5% of Japan’s GDP at the time.
In LEDC’s however, it’s a very different story. Haiti is the poorest country in the Western Hemisphere and ranked 149th out of 182 in the HDI (Human Development Index). The country suffers from extreme poverty (80% live under poverty line), high unemployment (60% unemployed), with majority of labour force working in the informal sector and adding to their woes, Haiti also owes hundreds of millions of pounds to the World Bank. Clearly the government has other more pressing issues to contend with rather than trying to deal with the ‘prospect’ of a natural disaster.
Consequently and in stark contrast to Kobe, Haiti was extremely underprepared for the earthquake that struck earlier this year. The country has no building regulations and so any potential infrastructure that was in place to help with the response was destroyed e.g. hospitals and transport facilities. Likewise, shanty-style housing built through self-help schemes simply collapsed or ‘pancaked’. There was confusion and mass panic as to who was in charge and able to lead the response resulting in widespread looting and a ‘strongest who survive’ approach. Whereas in Kobe, there was an unrivalled community spirit so much so that 1995 later became known as the ‘year of the volunteer’. Haiti also suffered from a shortage of essential supplies such as food, water, medicines and communication equipment. Many LEDC’s struggle to provide these key resources for day-to-day use, not to mention following the MEDC model of storing spare supplies in case of emergencies.
The rural-urban disparity is another major factor. Urban areas, particularly in LEDC’s, are prioritised when it comes to funding and government targeted development. Many would deem this to be warranted considering that the city is home to all the major social, economic and political institutions within a country. This lack of development in rural areas can spell disaster in the event of a natural hazard. China, a well established NIC and arguably an MEDC on many levels, experienced the problem of overlooking the countryside when a 7.9 magnitude earthquake hit Sichuan Province in May 2008.
The earthquake killed 69,175 people and left over 5 million homeless. In the rural of areas of Beichuan County, 80% of buildings were destroyed due to their age and shoddy construction. Much of the death and destruction caused by the earthquake stemmed from a lack of education and support system – no nearby emergency services. The Chinese Government were heavily criticised for their slow response, taking several days to declare a state of emergency and initially refusing offers of aid, with many believing the government were more concerned with their international reputation and hosting the Beijing Olympics later that year.
Overall the earthquake confirmed many peoples’ beliefs that rural China has been neglected and untouched by China’s economic rise. Health care is poor and infrastructure inadequate in rural inland areas like Sichuan Province and this is demonstrated by the comparatively higher death toll and number of casualties than in urban areas with similar strength earthquakes e.g. Kobe. All in all this highlights the widening gap between prosperous urban dwellers and struggling rural people in China. However, social inequality between rural and urban areas is not limited to China and is an issue in many countries worldwide.
This idea of rural-urban influences on earthquake hazardous can also be linked to population density. Cities tend to have a much higher population density than rural areas and so you would expect a larger amount of people to be affected by the earthquake. Although even some cities can have relatively low population densities, for instance the 2010 Christchurch Earthquake killed nobody and only injured two as New Zealand’s second biggest city has a population density of only 260 people per km2. (Kobe’s population density is over 10 times this!)
The weather and terrain is also more of an issue in rural areas and can often be responsible for delaying the emergency response. This is especially the case in mountainous areas where the risk of landslides blocking roads and accessibility to affected areas is a real concern. In the 2005 Pakistan Earthquake, mass movement was both an immediate and future risk for the people of Kashmir. Thousands of landslides blocked all transportation routes to and from the area, damming up the river and increasing the risk of flooding in the process.
The location of an earthquake in relation to its plate boundary will obviously be fundamental when assessing its associated levels of danger. It would be fair to say that in most cases, including Kobe and Sichuan, places situated at the point where destructive plates converge are at greater risk than those situated on a constructive boundary or away from the plate margin (mid-point earthquakes).
This is due to the fact that greater pressures are built up at this type of margin as one plate subducts beneath the other. However it is still debatable as to whether destructive boundaries produce more hazardous earthquakes than transform boundaries (conservative). Although the majority of the world’s deadliest and highest magnitude earthquakes have been on destructive plate margins, there have been several examples of transform boundaries causing significantly high death tolls. Most notably in Haiti this year, where it is believed as many as 200,000 people lost their lives.
The distance between the affected area and the earthquake’s epicentre is also important. The epicentre is the point on the earth’s surface directly above the earthquake focus and therefore land displacement and seismic activity is maximised at this point. Generally earthquakes which are within a few miles of the epicentre will experience greater suffering. For example Wenchuan County, the most severely hit area of the Sichuan Earthquake, was directly over the epicentre. The only exception to this is when the epicentre is off the coast as this increases the risk of tsunamis caused by displacement on the seabed, The 2004 Sumatra Earthquake and subsequent tsunamis killed over 230,000 people in fourteen countries despite the epicentre being over 120 miles away.