Since last week, hundreds of tremors have been recorded. On Tuesday morning, the strongest had a magnitude of 4.9.
Santorini, together with smaller islands, forms part of a volcano that last had a smaller eruption in 1950. But an expert panel studying the ongoing tremors has concluded that they "have no connection to volcanic activity".
Thus, no one knows why the ground is shaking or how long it will continue.
This is the first time this is happening, we have never seen it before, says research chief Athanassios Ganas on Greek TV.
Efthimios Lekkas, head of state tremor preparedness, sees hope in that the epicenter of the tremors now appears to be moving north, away from the island group. But even he expresses uncertainty.
This can last for days or weeks. We cannot predict the development, he says on TV.
The few tourists who remain get a unique chance to experience the world-famous whitewashed environments in solitude – something that is now rare even during the low season.
It's fantastic here, so beautiful, says Joseph Liu from Canton (Guangzhou) in southern China.
The tour guide told us about the tremors before we arrived, so they didn't come as a surprise.
The damage from the tremors is so far small. It can change if the magnitude increases to around 6.0 or higher, but experts say the risk of that is low.
