To what extent can preparedness and planning mitigate the effects of earthquakes?
Whittow in 1980 defines a hazard as a “perceived natural event which has the potential to threaten both life and property, and a disaster is the realisation of this hazard.” Earth hazards can therefore include all natural events including earthquakes, volcanoes, flooding and mass movement. Due to the very nature of these events “mitigating” (measures taken to reduce the impacts of a hazard beforehand) can be more successful for hazards such as volcanoes which are arguably more predicable than earthquakes and flash flooding. Despite the advances over the past few decades there is no “magic bullet” (Dr Charles Connor) in earth hazard prediction, and therefore mitigation – and the success remains very much dependent upon a number of factors including money available, and the number of vulnerable individuals.
Firstly, earthquakes, which are caused by sudden movements of the earth’s crust which result in violent shaking, liquefaction, and in extreme cases tsunamis, can to an extent be prepared for and mitigated for, and this is where money is being channelled into. Preparation and planning involves the retrofitting of buildings to create “earthquake-resistant” societies, aseismic design features (including concrete and steel frames to provide stability), as well as planning exclusion zones and evacuation routes in the case of an earthquake. Earthquake prediction is very closely linked to preparedness as if an event is expected; mitigating measures can take place beforehand to reduce the impacts. The earthquake storm theory which suggests that stress is transferred along a fault with each earthquake has predicted an earthquake to hit Izmit, Turkey, an extremely densely populated urban area. Consequently, the Turkish government are now channelling money into retrofitting buildings an enforcing them in order to prevent them turning into “death traps” when an earthquake strikes, which was the case in Mexico City in 1985. Consequently, this shows how mitigation and preparedness before an event has the potential to reduce impacts.
Additionally, Japan is very much at the forefront of disaster planning and earthquake preparedness. Disaster planning in Tokyo identifies parts of the city where buildings need upgrading as well as educating local people and ensuring they have emergency kits with essentials in them order to survive in the immediate aftermath of a quake before specialised help can reach them. The effects and success of planning and preparation in Japan can be seen in the case of the 1995 Kobe quake (7.2) which occurred on a destructive plate boundary in a subduction zone between the Pacific and Eurasian plates. It was predominantly the traditional buildings with heavy tiled roofs in the port of Japan, a “pocket of poverty” which collapsed. Additionally, it was due to effective planning in the densely populated LA Metropolitan region of California prior to the 1994 Northridge Earthquake which prevented the death toll exceeding 57. Therefore, it is evident that through appropriate preparation and planning, the effects, to some extent, can be mitigated for.
Preparedness and planning in the case of volcanoes can involve prediction as quite often through monitoring seismicity, (Bernard Chouet) ground inflation, and fumarolic behaviour a volcanic eruption, to a certain extent, can be predicted. Therefore, warnings, evacuations and exclusion zones are particularly effective in protecting populations from the primary hazards including lahars and lava flows. Prior to the Mt St Helen’s eruption on 18th May 1980, an evacuation zone of a 25 mile radius around the base of the volcano was successful in saving many lives, especially as the volcano erupted laterally. Furthermore, in 1991 a collaboration of US and Filipino volcanologists made an accurate forecast of the eruption of Mt Pinatubo, allowing the Philippine government to evacuate tens of thousands of residents, saving many lives.
However, it can be argued that the effects of earth hazards can only to a certain extent be prepared and mitigated for, primarily due to the unpredictability of their nature. Furthermore, despite planning and preparation, if the scale and size of an event is large enough, it is evident that the most prepared and resistant societies cannot even cope. This is the case with Japan who have earthquake proof buildings, sea walls surrounding much of the coastline, and over 1,000 GPS based sensors scattered throughout the country. Despite all this, the 9.0 mega thrust earthquake and tsunami (“one of the greatest forces of the planet”) which hit on March 11th 2011 overtopped 10m sea walls, inundated 470km2 of Japan, bringing widespread devastation including 15,000 deaths and 11,000 still missing. Therefore, it is apparent, that preparedness and disaster planning can only mitigate the effects of an earth hazard, such as a n earthquake to a certain extent. Perhaps, mitigation and planning is most effective when earthquake measure “mid-range” on the Richter scale, but once they exceed 9.0, no amount of preparation is going to be successful in reducing the impacts.
Mass movements, the downhill transfer of slope material as a coherent body, are often caused by the interaction of both human and physical factors. Theses events are often extremely quick onset and therefore difficult to prepare and plan for. However, measures can be taken to ensure slope stability and dynamic equilibrium to oppose the resisting downward forces to help prevent such an event. For example, studies by Temple and Rapp (1980) showed that in forested areas mass sliding was rare and in the Annapurna region in the foothills of Nepal, the slopes are being planted with vegetation in orer to reduce water on the slopes and to bind the soil together. Similarly, land use control can be implemented, such as in Venezuela (following the 1999 debris flow, affecting 214,000, killing 30,000) in order to help reduce the effects of a disaster in the future.
Vulnerability is one of the main problems when it comes to mitigating and preparing for disasters. Closely related to poverty, areas such as Haiti and Sichuan in China were unable to mitigate for and prepare for the earthquakes which struck. This is because on of the limits to preparation and planning is a lack of funds. In the area of Sichuan, seismic building codes and not be obeyed and buildings were poorly constructed resulting in over 200,000 deaths in 2008 when the earthquake hit the region. Additionally, in the Port au Prince region of Haiti, the poorest country in the Western hemisphere, with 3 million in the city living in poverty, little had been done to build an earthquake resistant society, and so the effects caused by the 7.0 earthquake in January 2010 were long term and widespread.
Overall, in conclusion, it is evident that to a certain extent, depending on the earth hazard, preparation and planning can mitigate the effects of a hazard. However, success is dependent on a number of factors including vulnerability, exposure, the size and scale of the hazard, and the amount of money available. It must also be noted that although preparation and planning can reduce the humanitarian effects, the economic impacts are another story. Despite only 57 deaths in California in 1994, the Northridge quake was the most economically devastating and the Pakistan floods of summer 2010 destroyed 17.5 million hectares of fertile agricultural land, affecting the livelihoods of local people, but also impacting the textile industry, Pakistan’s largest exporter.