Six straight days of minor tremors have stoked fears of a possible major earthquake or volcanic eruption.
Authorities in the Azores islands are preparing for the possible evacuation of citizens amid fears of a major environmental disaster.
The Portuguese archipelago has been hit with six consecutive days of minor tremors, stoking concerns about a major earthquake or volcanic eruption.
The region's CIVISA seismo-volcanic surveillance centre has raised the volcanic alert to level 4 out of 5, meaning there is a "real possibility of eruption".
The president of the islands' regional government said on Thursday that airlines are increasing the number of flights into and out of São Jorge, where around 8,300 people live.
“Anything could happen [but] nothing might happen,” Azores president José Manuel Bolieiro told reporters.
Scientists say it is hard to predict the consequences of the persistent, though low-intensity, seismic activity.
The island municipality of Velas -- which has around 3,000 inhabitants -- has been the epicentre of more than 2,000 minor earthquakes alone since March 19. Officials are transporting elderly residents to another part of the island as a precautionary measure.
Emergency services have also established safe corridors for traffic and temporary accommodation for evacuees on the eastern side of the island.
Any public alerts about an earthquake or eruption will be transmitted on local radio, social media or by ringing church bells, officials say.
São Jorge is one of the nine islands that make up the Azores, which lie roughly 1,500 kilometers west of the Portuguese mainland. A line of dormant volcanic cones extends along the island’s central ridge.
The last volcanic eruption on land in the Azores was in 1957, on Faial Island, while an earthquake on the same island in 1998 killed 10 people.