Santorini's earthquake swarm is declining gradually as thousands return to the Greek island

ATHENS, Greece — An earthquake swarm near the island of Santorini is gradually declining a month after it began, Greek scientists monitoring the phenomenon said Monday.

The undersea shocks — sometimes recorded only minutes apart — led thousands of residents and workers to flee the famed clifftop towns of Santorini as well as the nearby islands of Ios, Amorgos and Anafi.

Schools remain closed on those islands for a fourth week and many other restrictions are still in effect. But scientists said they were encouraged by the decline of the earthquake swarm.

“Seismic activity continues to show a gradual decline, both in terms of the daily number of recorded earthquakes and maximum magnitudes,” the Interdisciplinary Committee for Risk and Crisis Management at the University of Athens said.

“The activity remains concentrated in the same focal area ... with no new micro-seismic surges observed since Feb. 15,” it said.

The committee said it recorded more than 20,000 earthquakes of magnitude 1 or higher between Jan. 26 and Feb. 22.

The multiple earthquakes, attributed to natural tectonic processes as well as magma movements below the seabed, have measured up to magnitude 5.3 but have caused only minor damage.

Santorini Mayor Nikos Zorzos on Monday said several thousand people had returned to the island since late last week, and called on government authorities to provide additional assistance in dealing with risks — including controlling rockfalls and the installation and repair of hillslope fencing.