Sunday, October 17, 2010

Earthquakes in Barcelona


When there is an earthquake somewhere in our planet, the first piece of information that we get is its magnitude, which can be measured on the Mercali Scale (measuring earthquake intensity in terms of material damages) or the Richter Scale (measuring released energy). Needless to say, the initial chaos after an earthquake makes it difficult to know exactly the number of casualties and the effects on the towns and villages around the epicentral area, so that’s why magnitude is such an important piece of information.
But magnitude is not always the most reliable information to know the degree of destructiveness of an earthquake. In early 2010 Chile suffered an earthquake reaching 9.2 magnitude on Richter Scale, becoming one of the most powerful earthquakes of our recent history. More than 700 people died and some parts of the country were destroyed. Just one month earlier, Haiti suffered from an earthquake measuring 7 on Richter Scale, but it caused 200,000 deaths and it destroyed most of the country. In order to better understand the difference in earthquake power, bear in mind that the Richter Scale is not linear so a difference in magnitude of 2.2 means that the earthquake in Chile was 65 times more powerful than the earthquake in Haiti.
Then, what makes an earthquake deadly? Besides magnitude, there are two factors to be taken into account. First, our response to emergencies: are there good hospitals, civil defence or other trained organisation to rescue and attend victims? Or can medical supplies, food and drinking water be soon provided on the affected site? And secondly, are buildings, roads and other infrastructures prepared? These two factors made the difference between Chile and Haiti.  Chileans are used to earthquakes: the largest earthquake that has ever been recorded reached 9.5 magnitude on Richter Scale and it was felt in Chile in 1960. Therefore, Chilean buildings are adapted to face earthquakes, whereas Haitian traditional buildings made of palm wood (lighter and more flexible) have been replaced by modern buildings made of poor materials. Some countries with high seismic activity like Chile, Japan or the West Coast of the United States are better prepared to face earthquakes.
But what about Barcelona? What would happen if such an earthquake occurred in Barcelona? Probably, our response would be quite efficient, but prevention is our weak point. Very few buildings in Barcelona are prepared to suffer a tremor and many of them lean on party walls of the building next door, especially in the case of old houses. An earthquake like the one in Chile could destroy most of Barcelona.  
Although Barcelona is not in a high-risk area, seismic safety is very poor. Not too long ago, in 1755, an earthquake measuring 9 on Richter Scale caused total destruction of Lisbon and 60,000 to 100,000 people died, resulting in one third of its population.
We often think that these things happen far from our home and that we are better prepared…

Sources:
  1. Earthquakes happen every day. This web shows the most recent ones: http://www.iris.edu/seismon/
  2. Richter scale: http://en.wikipedia.org/wiki/Richter_magnitude_scale
  3. Mercali scale: http://en.wikipedia.org/wiki/Mercalli_intensity_scale
  4.    

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