The tourist hotspot has been rocked by seismic activity this week with thousands of earthquakes recorded since Sunday.
On Thursday evening, a 4.6 magnitude quake was recorded at 20:16 local time (18:00 GMT) in the sea between Santorini and another island, Amorgos, followed by a 4.2 magnitude quake roughly two hours later.
Santorini residents have begun night patrols amid fears of looting on the island, which has largely been left deserted as most residents have left.
More than 11,000 people have departed as authorities report earthquakes are being recorded on a minute-by-minute interval.
Experts have warned it is unclear when this period of "seismic crisis" on the popular tourist island might end.
Thursday's quakes have so far not been as severe as the 5.2 magnitude shock which occurred on Wednesday in waters between the two Greek islands.
So far no injuries have been reported, and there has also been no major damage on the island.
But authorities are preparing in case a larger quake hits. On Wednesday, they warned of landslide risks to parts of the island.
Magnitude refers to the size of an earthquake, with increases marked as decimal points.
A magnitude 6.0 and above is considered severe, whereas a magnitude 5.2, the strongest experienced so far in the region, is considered moderate.
AzVision.az
