EL PASO, Canary Islands (AP) — Several small earthquakes shook the Spanish island of La Palma off northwest Africa in the early hours of Tuesday, keeping nerves on edge as rivers of lava continued to flow toward the sea and a new vent blew open on the mountainside.

The new vent is 900 meters (3,000 feet) north of the Cumbre Vieja ridge, where the volcano first erupted on Sunday after a week of thousands of small earthquakes.

That so-called earthquake swarm gave authorities warning that an eruption was likely and allowed more than 5,000 people to be evacuated, avoiding casualties.

The new fissure opened after what the Canary Islands Volcanology Institute said was a 3.8-magnitude quake late Monday.

La Palma, with a population of some 85,000 people, is part of the volcanic Canary Islands.

Lava by Tuesday had covered 106 hectares (about 260 acres) of terrain and destroyed 166 houses and other buildings, according to the European Union’s Earth Observation Program, called Copernicus.

Unstoppable rivers of lava, as much as six meters (nearly 20 feet) high, rolled down hillsides, burning and crushing everything in their path.

Authorities said the pace of the lava’s advance appeared to have slowed and didn’t expect it to reach the sea before Wednesday at the earliest, Spanish private news agency Europa Press reported.

When it reaches the Atlantic Ocean, it could cause explosions and produce clouds of toxic gas. Scientists monitoring the lava measured it at more than 1,000 C (more than 1,800 F).

Scientists say the lava flows could last for weeks or months. The volcano has been spewing out between 8,000 and 10,500 tons of sulfur dioxide a day, the Volcanology Institute said.