An earthquake measuring 4.2 on the Richter scale was recorded early on Friday afternoon in a sea area off the southeastern Aegean island of Nisyros, according to an announcement published by the Geodynamics Institute of the National Observatory of Athens.
The epicenter was reported 34 kilometers southwest of Nisyros, the institute said.
Another milder quake occurred a few hours later in the sea area south and southwest of Tilos.
It measured 3.6 on the Richter scale and occurred at a depth of 10 kilometers.
The two quakes followed continuous seismic activity in the wider area between Tilos and Nisyros earlier on Friday and on previous days.
The tremors were felt by the inhabitants of the two islands without causing concern.
Local authorities on both islands were in contact with seismologists who are monitoring the seismic activity.