Tuesday, February 16, 2010


Turkish gov't calls for 'buffer zones' to protect cities from earthquakes

Turkey’s ruling government is calling for new regulations on development near fault lines that would restrict construction to a certain distance depending on the depth of the fault and require that current structures are relocated or vacated in time. Experts say the government’s plan is ambitious and well intentioned but useless in the long runNew regulations to reduce the number of deaths in the much-debated “impending big earthquake” in Turkey include strict development rules near fault lines, but experts say the buffer zones would not be useful, especially for Istanbul.
Experts said such precautions should only be applied to certain fault lines and not to Istanbul because the fault line through the city snakes beneath the Sea of Marmara, not under the city itself. But many other Turkish cities also suffer from seismic threats because of developed areas that are built over fault lines and the buffer zones may be helpful in deterring construction too close to the faults.
The Turkish public has been discussing precautions against a possible earthquake since the Aug. 17, 1999, Gölcük earthquake in the Marmara region that killed nearly 20,000 people and razed entire urban areas to the ground.To mitigate an earthquake’s possible effects, the government’s proposal envisions the construction of buffer zones on active fault lines and the banning of any construction or settlements in these areas, according to the daily Milliyet.
The draft, prepared by the Earthquake Department under the Prime Ministry Disaster and Emergency Department, said the buffer zones would extend to “75, 150 or 250 meters on each side of the fault lines.” For fault lines that are larger than others, however, the draft calls for proportionally larger buffer zones.
Buildings that are already located in the proposed buffer zones will be reinforced and permitted to remain in use until their economic life is complete. An international report released in 2007 predicted an earthquake of 7.5 on the Richter scale in Istanbul within three decades.
İdris Güllüce, head of the Parliamentary Earthquake Commission as well as a deputy for the ruling Justice and Development Party, or AKP, said he was “terrified” and “unable to sleep” after reading the report prepared by Japanese experts, according to a Feb. 6 Anatolia news agency story.
Seismologists contacted by the Hürriyet Daily News & Economic Review, however, said such buffer zones would have few benefits if implemented in Istanbul. “The fault line lies under the Sea of Marmara and the closest fault line to Istanbul is eight kilometers away,” said Professor Celal Şengör of the Eurasia Institute of Earth Sciences at Istanbul Technical University.
Şengör also said he does not take the Prime Ministry report seriously because they do not follow up-to-date reports about earthquakes.“They read the facts about a possible Istanbul earthquake from second-hand sources, but we have conducted research ourselves and have been discussing these problems for many years now,” said Şengör in reference to Güllüce’s speech.
He said the buffer zone approach could provide a precaution for the rest of Turkey, but was not a truly effective solution.
Professor Aral I. Okay, also of the Eurasia Institute of Earth Sciences, told the Daily News that experts usually predict that earthquakes will occur on an active fault line or a fault line that was damaged during a previous quake. Because of this, mapping these lines and preparing buffer zones could be beneficial just in knowing where they are but in the long run they would be useless for Istanbul, he said.
An area is damaged during earthquakes depending on its distance from a fault line, yet other factors also affect the scope of the damage, said Okay, adding that the structure of the surface as well as quality and resistance of the buildings are also significant factors.
Murat Nurlu, head of the Earthquake Department, informed the parliamentary commission of the draft regulation and said a change of regulations would be implemented as had already been done in the United States and New Zealand.
“The regulations of the European Union and the U.S. should be a basis for Turkey’s regulatory changes,” said an expert from an Ankara-based association, who spoke on condition of anonymity.
The Mining Exploration Institute, or MTA, will prepare a 1/25,000 scale map including current data about fault lines with plans to renew the map in four years, according to the draft regulation prepared by experts Ramazan Demirtaş and Murat Yavaş. The regulation says the buffer zones will be identified after the geographical location and characteristics of the active fault lines are determined.

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