Saturday, 14 May 2011

Earthquake Prediction and Disaster Risk Reduction

Exposed Fault Line (Greece)
After 'what type of rock is this?' the question I probably get asked most as a geologist is 'can we or will we ever be able to predict earthquakes?' Accurate earthquake prediction is considered one of the 'holy grails' of the geosciences. It remains elusive however, and is likely to be elusive for the foreseeable future.

Earthquakes are triggered when stress builds up on these fault lines, as the stress overcomes a critical value the fault ruptures, releasing this stress (or transferring it to other parts of the fault). This release of stress generates seismic waves which shake the ground. Earthquakes cause considerable damage and loss of life across the globe - seen recently in places as diverse as Spain, Japan, New Zealand, Burma, Chile and Haiti. 

Major Plate Boundaries
Geoscientists have a good idea of roughly where earthquakes are likely to happen (although new fault lines are still being discovered). They have an indication of the maximum magnitude we can expect in certain places (though again, there can be surprises, such as the March 2011 earthquake in Japan). Studies of palaeoseismology (historical earthquakes) can also give us an indication of what time frames to expect between large earthquakes. Despite this knowledge and ability to understand these factors - geoscientists have no way to predict exactly when, where and how big a particular earthquake will be. 

Research is examining possible methods of earthquake prediction, including study of animal behaviour and study of electrical disturbances in our atmosphere. This research is a long way away, however, from giving us the vital information we need for earthquake prediction, and current opinion remains uncertain as to whether it will eventually help. 

Bendandi (Source: Luca Lorenzi)
Despite geologists stating that earthquake prediction is a distant dream - predictions are occasionally mentioned, such as the May 11th 2011 Rome earthquake. Rumours had circulated that a dead seismologist (Raffaele Bendandi, pictured left) had predicted that the city would be destroyed on this date. Rumours which caused widespread panic and thousands to stay away from the city. This situation highlights something that isn't talked about very much - the potential dangers of earthquake prediction. Currently earthquake prediction (with precise days and times etc) mainly causes unfounded panic and distress. It damages economies, and has the potential to lead to people not paying attention to genuine warnings and evacuation orders. Even if we do get into a situation where we can predict earthquakes using scientific monitoring techniques, there is of course the potential that those predictions will be wrong. The potential for panic, damage and reluctance to pay attention to genuine warnings means that distributing these warnings must be carefully considered. Earthquake prediction also places a huge burden on local, national and international governments to ensure they can manage and finance evacuations, as well as effectively mobilising communities. While this isn't a danger to, or reason not to predict - it does mean international governments and agencies must be ready to step in and support struggling countries.

Finally, while we cannot (and may not ever) predict earthquakes in the sense of specific location, magnitude and time - we do have a wealth of scientific and technical knowledge about how earthquakes behave, how soils and rock respond to seismic waves, how buildings respond... not to mention many locations prone to earthquakes, and significant historical records giving us an indication of time intervals and magnitude of earthquakes. The huge amounts of scientific data and technical knowledge we have means that we can develop effective disaster risk reduction methods. Earthquakes, and other natural hazards, only become natural disasters when there is risk and vulnerability. If this vulnerability can be reduced, and resilience increased then the impacts of hazards such as earthquakes will be dramatically reduced. The types of things that can be implemented to ensure risk is reduced are things such as changes to urban planning - ensuring that cities are built with stricter building codes, more organisation and planning, and better assigned routes for evacuation and emergency vehicles. This is particularly important in developing countries, where rapid urbanisation in vulnerable areas could lead to potential mega-disasters. Other things such as education and drills, ensuring that people know what to do and how to do it, is crucial. This can be particularly important in institutions such as schools and health centres.

So while earthquake prediction is widely considered the 'holy grail' of the geosciences - we mustn't deflect from the importance of what we can already do. We have the ability to significantly reduce the impacts of disasters - and must work to ensure disaster risk reduction is incorporated into policy, well financed and given our full backing.   

Read more: