Authorities on a mid-Atlantic Portuguese volcanic island that has recently been hit by thousands of small earthquakes are planning evacuations in case the situation worsens.

Around 2,000 earthquakes have been recorded on Sao Jorge in the Azores archipelago since Saturday, according to Luis Silveira, mayor of Velas.

According to the region’s CIVISA seismo-volcanic surveillance center, there is concern that the earthquakes, with magnitudes ranging from 1.6 to 3.3, could cause a stronger tremor or a volcanic eruption.

CIVISA has raised the volcanic alert to level 4 out 5, meaning there is “real possibility of eruption”, said Clelio Meneses, the regional secretary responsible for the Civil Protection authority. “What we are doing is preparing for the worst case scenario,” Meneses said.

The small quakes, which have caused no damage so far, were reported along the island’s volcanic fissure of Manadas, which last erupted in 1808. A big earthquake hit the island in 1980, causing severe damage.

Silveira said those in hospital or in care homes in Velas were being transferred to Calheta on the other side of the island. He said civil parishes in Velas were also preparing to transfer those with reduced mobility.

Plans to evacuate the rest of the population to Calheta or to other islands would only be activated if needed, he said.

Sao Jorge, one of nine islands that make up the Azores, is home to about 8,400 people and is part of the archipelago’s central group, which includes the popular tourist destinations of Faial and Pico, which are also volcanic.

“We recommend that people have a backpack prepared with the bare minimum, such as a change of clothes, medication and some food,” Silveira said.

He said the military and air force were prepared to help and that a navy vessel was on its way. The Portuguese Red Cross is sending beds to the island.

The sudden increase in seismic activity is reminiscent of the earthquakes detected before the eruption of the Cumbre Vieja volcano on Spain’s La Palma island last year, some 1,400 km (870 miles) southeast of the Azores.