Just a few months ago a tsunami devastated the coast of Indonesia and left more than 190,000 people dead. The lack of prevention measures and the ignorance of the real risks in an area with such seismic activity were some of the factors that increased the effects of the seaquake. To avoid similar events in future in the South of Spain, a research team of the University of Granada, in collaboration with Italian scientists, has set a project that has analysed the epicentres of the earthquakes happened in the past to determine the risks they could cause in future.
Until the moment, nobody knew the exact point where the disasters started, like the earthquake of Alhama in 1884 or that of Malaga in 1680, as the seismic stations that record the earthquakes and send the signal to the observatories to determine their localization did not start to work all-out until the beginning of the 20th century. According to the geo-physicist and professor of the University of Granada Jesús Ibáñez Godoy, “the only trace that remains of historical earthquakes is their capacity for destruction, but in most cases we do not know their epicentre, a very important data if we take into account that they could happen again in future with the same intensity and in the same place”.
In this sense, Ibañez points out that very often the epicentre of the earthquake was not in the devastated area –this is the case of Alhama and of the earthquake that destroyed Lisbon in 1755 whose centre was in Cape San Vicente- but in a nearby area that due to the absence of population did not suffer the effects so much. But, several centuries later, such areas, where there were movements of six degrees in the Richter scale, could be inhabited, and therefore it is so important to determine “where the earthquakes originated”.
Location
The method used by geophysicists of Granada to locate the epicentre of the seismic movements that took place several centuries ago has been the distribution by areas through a mathematical technique designed by them of the areas where the damages occurred to locate from there where the epicentre was.
The data extracted from this work are very useful to prepare risk maps. They will take into account not only the areas destroyed by the earthquake, but also the place where it originated and, therefore, the most liable to suffer damages in future. But this new contribution will not only be useful to get to know something more about the seismic past of the south of Spain but also to “carry out prevention measures that consider feasible construction formulas, edifications in compacted lands r the exact location of the areas that run higher risks in future to avoid major damage”, Ibáñez says.
Reference
Prof Jesús M. Ibáñez Godoy
Andalusian Institute of Geophysics and Seismic Disaster Prevention.
Phone numbers: 958 242 733/ 243 556
E-mail. ibanez@iag.ugr.es
