I interviewed Philippe Jousset PhD, from the International Centre for Geothermal Research and Martin Mai a professor of geophysics specialising in the physics of earthquakes to find out more about earthquakes in Albania.
What is the likelihood of another large earthquake of a similar magnitude or higher in Albania in the coming weeks?
It is impossible to predict future earthquake activity. We know where earthquakes happened in the (recent) past and hence where they may happen again because faults are reported and monitored, but the exact time of occurrence is very challenging to predict.
Typically, aftershocks are of much smaller magnitude than the mainshock; statistically speaking, the largest aftershock is about one magnitude unit smaller than the mainshock. However, there have been cases where aftershocks were of the same or even larger magnitude (seismologists then refer to ‘earthquake doublets’). Usually, the aftershock activity decreases over weeks and months to follow, both in number of events and their magnitude. But it is very difficult to provide accurate calculations of earthquake probabilities.
This is one of the largest quakes the area has seen in a long time, why is this?
This area has been prone to larger earthquakes in the past and therefore it could be the place of further earthquakes. Most of the Mediterranean area actually is prone to earthquakes due to the tectonic movement of African plate towards the north. This tectonic movement may trigger earthquakes in Greece, Italy, Spain, France, Albania, and others. When there is no earthquake during a longer period of time (say, several decades to even centuries) in an area where earthquakes have been reported in the past, the next one may be larger. How long one has to wait for the next “similar-sized” earthquake in the region is difficult to assess and requires detailed statistical analysis based ideally on many data/observations of earthquakes for a long period of time. In most cases, we have high-quality observations only for about 60 years, a time period too short in practice to reliable estimate the statistics of earthquake recurrence times.
What should we do in case of an earthquake?
For Japan, there are very useful recommendations of actions to be taken in case of an earthquake; as you know, Japan is a country of frequent large earthquakes. Closer to us, recommendations are also given in Italy and in France. There are certainly also recommendations given by Albanian authorities. Those are generally given with different importance/focus related to the occurrence time of the earthquake.
1. Be prepared: prepare and maintain a set of food for few days, have a portable lamp with regularly updated batteries, a cover sheet and other set of survival equipment. Those food and items should be stored in a known and accessible place – close to the entry of the apartment. 2. Be calm: At the time of the earthquake, go into the middle of the street away from tall buildings or in the garden if you can. If you cannot go outside, you can go under a strong table and under thicker walls between rooms 3. Be proactive: Reconstructing and retrofitting your house is an important step as well, following recommendations given by the local authorities based on seismic hazard studies for the region.
What should governments do in order to prepare better for these events?
Governments should provide this kind of information and impose laws on following seismic construction codes. Regional-scale and nation-wide seismic hazard studies need to be conducted and then applied to develop seismic building codes and retrofitting activities.
In Europe, a range of international projects have developed pan-European seismic hazard maps that provide a very good resource for local & regional authorities to be prepared for future earthquakes.
Following resources come to mind:
http://www.efehr.org/en/home/ http://data.euro.who.int/e-atlas/europe/images/map/albania/alb-seismic.pdf
Why does Albania get so many smaller earthquakes?
The tectonic setting of the area makes it subject to the occurrence of relatively “smaller” earthquakes. In other words, very large magnitude M 8 earthquakes in the region are probably highly unlikely, but not impossible. The size of earthquakes in a given region depends on many geological and physical factors, that we cannot explain in detail here. In short, scientists do their best to apply new technologies, methods to understand the occurrence in time and space of earthquakes.
Are the amount of quakes increasing in the area?
There were earthquakes in the past. The occurrence of earthquakes in future in this area is certain, however predicting their size or their exact timing is actually not possible at the present. Over longer periods of time, say decades, the earthquake rate does not change, at least that is what earthquake statistics (derived over a limited period of time). However, the increased aftershock activity after large “mainshock” is normal and expected. The more stations we put to record earthquakes and aftershocks, the more we detect smaller earthquakes, which may give the impression that there are more earthquakes, but there are not more earthquakes, it is just that we record them better.
Can you tell us anything to reassure or calm people?
Explanation on why earthquakes occur in this area is important – see above as this helps people understand what is happening, and accept it – we have no choice, our Earth is seismically active. Giving advice on how to react to the earthquake occurrence is a good thing as well. There is an international concern about what is going on in Albania. Several scientific initiatives are also discussed. Note that a European initiative (Italy, France, Germany) is being prepared to deploy at least 30 additional seismic stations in order to study the aftershock sequence.
Follow The Balkanista!
