The Mayor of a Turkish city has suggested a magnitude 6.2 quake which hit the Aegean Sea could have been the result of seismic testing.
The quake hit south of the island of Lesbos on Monday (local time), killing one woman, injuring 10 and badly damaging buildings and roads.
There were at least 25 recorded aftershocks shortly afterward.
Ankara Mayor Ibrahim Melih Gökçek has suggested in a series of tweets the tremor was "man-made", and "must be investigated".
"Now I think that this might be an artificial earthquake. I do not say it is certain but it is a very serious possibility," Mr Gökçek tweeted.
"I say that it should definitely be investigated. Was there any seismic research ship sailing near the epicenter? If so, which country does it belong to?" he said.
Ankara is around 580km away from the quake's epicentre.
It isn't the first time Mr Gökçek has suggested an earthquake was created by humans; in February, he suggested the same thing after a quake in Turkey's western province of Çanakkale.
New Zealand scientists and the oil industry have both rubbished claims offshore seismic surveying can create earthquakes.
"There is absolutely no scientific basis to support claims that offshore seismic surveying in any way causes earthquakes or triggers a fault," Petroleum Exploration and Production Association of New Zealand chief executive Cameron Madgwick told Newshub last year.
Offshore seismic surveying involves a vessel sending a soundwave to the seabed. The information which bounces back gives a picture of the geology under the seabed.
GNS seismologist John Ristau said the techniques used by the ships "pale in comparison to even a moderate-sized earthquake, so they'd have no effect on causing earthquakes".