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Back to Otro terremoto superficial catastrófico: Van (Turquía)

Antonio Aretxabala Díez, Geologist and Director technical laboratory of Building, Professor of Geomorphology and Geotechnics .

Another catastrophic surface earthquake: Van (Turkey)

Tue, 25 Oct 2011 09:09:54 +0000 Posted in La Rioja, El Correo (Álava and Vizcaya), Lavozdigital.es, El Comercio, Diario Sur, La Verdad, Diario Vasco, Hoy, Que, Las Provincias, Urbanism, Ideal (Granada), El Diario Montañés

More and more voices are being raised calling for specific urban planning in seismic zones, the paradigm focused on the optimization of seismic-resistant standards considers that earthquakes act only on the "parts" of the system: the buildings, rather than on the real seismic scenario: the city.

But what is happening? since the destruction of Bam, a UNESCO heritage site in Iran in 2003, l'Aquila in 2009, Lorca this year and now Van in Turkey, earthquakes whose foci are less than 10 km deep seem to be ravaging the surface of Europe and the part we tectonically share with the East.

The configuration of all of them is located between the Azores, Gibraltar, Italy, Greece, Turkey and reaches India, where the plates and their small European, Asian and African pieces play the dangerous game of friction, like dominoes pushed by the finger of Poseidon and his bad temper; catastrophic seismic movements and reactivation of volcanoes such as Etna or Iron, or those of Iceland, etc., every day a telluric surprise.

Lorca (4.4 and 5.1) and l'Aquila (5.8) did not even reach 6 on the Richter scale, Bam (6.2) and Van (7.2) all have something in common: they are shallow and close to urban centers. An event of scale 8 in the Monegros would be less frightening, no doubt. So the magnitude alone is not an explanation for the violence of Poseidon.

The more we refine in the provision of earthquake-resistant building regulations, the more we invest in reinforced and calculated buildings to avoid resonance with seismic waves, the more deaths and misfortunes we seem to have in store for us. Either we are not doing something right or Poseidon is getting angrier and angrier.

Could it be that we are not approaching the problem correctly? Every time there is an earthquake anywhere in the world, the immediate reports made that point to the causes of the victims (as in Lorca 100%) show that the buildings that have killed, present designs identified in previous experiences as not suitable for seismic areas, as well as human settlements built on real sounding boards or seismic magnifying glasses, capable of doubling and even tripling the strength of seismic waves.

One thing must be clear: seismic-resistant construction standards have not been, are not and never will be enough to save lives.

Urban planning regulations are those that determine the volumetric framework (usually by space optimization) of a building, without anti-seismic design plans; they consider that earthquakes act only on the "parts" of the system (e.g. NCSE-02 or EHE), i.e. buildings and their Structures, instead of on the real seismic scenario: the city.

More lives will be saved by urban plans in accordance with the seismotectonic reality, the Education of the population before, during and after an earthquake, the correct design of the non-structural part of the buildings (cornices, balconies, parapets, overhangs...) and the awareness that from the Azores to India, especially the whole territory facing the Mediterranean, should in the future have special plans for the distribution of the territory. Applicable especially to those historical areas with a remarkable heritage density, some of them already destroyed, such as Bam, Lorca or l'Aquila, but also appropriate urban plans should be developed in those cities close to active faults.

The problem is that not much has been invested in getting to know them. Even the general plan of Lorca paradoxically contemplates the segment of the FAM (Falla de Alhama de Murcia), as it passes through the Guadalentín, as a point of scientific interest to be preserved. The bad thing about the lack of knowledge of the environment is that this point of interest can affect the city, and a lot.

This discussion was already very present in Turkey since the 1999 Marmara earthquake. It showed that 60% of Turkish buildings were vulnerable to the earthquake. Two researchers: Handan Türkoglu and Seda Kundak recently presented a work graduate "urban transformation as tool for disaster mitigation" today being applied in Istanbul, a city of 9 million inhabitants expecting a major earthquake in the next 30 years. The Turkish government has already set urban planning as the first tool to mitigate seismic disasters in the future, what will the rest of us do?

We will have to wake up and advance more in this line, it is clear, not to continue only substituting some standards of Building for others more and more demanding, the restrictions to construct buildings in recognized seismic zones are already many and very few urban planning, almost the same as in non-seismic zones, even less is taken into account the historical heritage, although we are worse off if we are honest and think how little we know about these "hidden" faults.