If you live near Rennes in Brittany and felt the earth tremble in Brittany in the early hours of Thursday then you weren't dreaming.
At around 3.45am, an earthquake measuring 3.9 on the Richter scale was recorded, around 28 kilometres to the south east of Rennes.
“I was in bed when, all of a sudden, I heard a a noise and the earth started vibrating,” one witness told the Ouest France newspaper.
“It only lasted a few seconds but it was truly frightening.”
While no injuries or major structural damage were reported, hundreds of people responded when the local Ouest France Brest newspaper asked if its Facebook followers felt anything.
The earthquake struck at a depth of 2 kilometres and was just one kilometre from the small town of Le Theil-de-Bretagne.
If you're thinking that this story sounds familiar - a small quake sending tremors around Brittany - then you're not wrong.
In fact, there have been over 500 similar quakes since the year 2000.
So why is Brittany such a hub for earthquakes?
Rémy Bossu, the head of the European-Mediterranean Seismological Centre (EMSC), says it's all because of the African plate.
“In short Brittany is one of the seismically active regions in metropolitan France,” Bossu told The Local.
“All the seismicity in metropolitan France is linked to the push northward of the African plate. This push reactivates old faults in Brittany and in other part of France (the Alps, the Pyrénees, the Massif Central, and the Rhenan rift).”
He pointed out that over the last 50 years Brittany has been particularly hit by quakes compared to the rest of France (see map below).
So when is the big one going to hit?
Bossu says that while there has been no history of very large quakes in Brittany, that doesn't mean it couldn't happen.
“One cannot exclude the possibility of a huge earthquake in Brittany, but the thing is that nobody knows when it would strike - you just can't predict when they strike,” he said.
What's more important is to know how to protect yourself in the event of a quake, he said.
“The main message is that in a moderate quake, you need to protect yourself first by getting under a table, then wait until the shaking stops before leaving the building,” he said.
“The most likely way people get injured is getting hit by falling objects, like light fixtures or objects from shelves.”
“And don't phone emergency services for information, as it can block the lines and prevent help for real emergencies.”