Turkish scientists split on ‘slow earthquake’ debate

ISTANBUL

The North Anatolian fault lies very close to the Princes' Islands area of Istanbul.

Turkey’s leading scientists are split over a scientific article on claims over a large but slow earthquake in 2016, which reportedly lasted around 50 days.

A magnitude-5.8 earthquake took about 50 days to shake itself out, according to an article on the Earth and Planetary Science Letters, which was cited by The Guardian on Feb 5.

However, “There is no such a thing called ‘slow earthquake’,” said Prof. Övgün Ahmet Ercan of the Istanbul Technical University (İTÜ).

“Energy emerges during earthquakes and it does not come out slowly,” he told Hürriyet.

“And there is a slow downslope, which we name ‘creep,’ that cannot be named as an earthquake,” he said, referring to the slow downslope movement of particles without any fault.

Prof. Şerif Barış of Kocaeli University disagreed, saying that “slow earthquake” is a decades-old concept.

“It means the very slow breaking. There are such records in the literature,” he said.

“They occur where the earthquake networks are dense,” he said, adding that a special analysis and correct software are needed to mark them.

Occurring a few kilometers south of Istanbul, this “slow earthquake,” which took place during the summer of 2016, “could be a sign that the dangerous North Anatolian fault is reawakening,” The Guardian said.

“Geologists know that the strain is travelling from east to west across Turkey, caused by Asia ploughing into Europe,” it said.

Large earthquakes have sequentially released strain along the east-west trending North Anatolian fault, with the most recent being the devastating magnitude 7.6 Marmara earthquake in 1999, which killed more than 17,000 people.

Turkey’s most populous city Istanbul and the surrounding area are next in line.

Scientists reported in the Earth and Planetary Science Letters that they had spotted the slow quake using strain-meter data from a borehole in the region. Had it released its energy in one go it would have been equivalent to a magnitude 5.8 quake.

“It may have brought other parts of the fault closer to failure, but we need more data to get the full picture,” said the paper’s lead author, Patricia Martínez-Garzón.